/**
 * Forms the symbols available to all D programs. Includes Object, which is
 * the root of the class object hierarchy.  This module is implicitly
 * imported.
 * Macros:
 *      WIKI = Object
 *
 * Copyright: Copyright Digital Mars 2000 - 2011.
 * License:   $(WEB www.boost.org/LICENSE_1_0.txt, Boost License 1.0).
 * Authors:   Walter Bright, Sean Kelly
 */

/*          Copyright Digital Mars 2000 - 2011.
 * Distributed under the Boost Software License, Version 1.0.
 *    (See accompanying file LICENSE or copy at
 *          http://www.boost.org/LICENSE_1_0.txt)
 */
module object;

private
{
    extern (C) Object _d_newclass(const TypeInfo_Class ci);
    extern (C) void rt_finalize(void *data, bool det=true);
}

// NOTE: For some reason, this declaration method doesn't work
//       in this particular file (and this file only).  It must
//       be a DMD thing.
//alias typeof(int.sizeof)                    size_t;
//alias typeof(cast(void*)0 - cast(void*)0)   ptrdiff_t;

version(D_LP64)
{
    alias ulong size_t;
    alias long  ptrdiff_t;
}
else
{
    alias uint  size_t;
    alias int   ptrdiff_t;
}

alias ptrdiff_t sizediff_t; //For backwards compatibility only.

alias size_t hash_t; //For backwards compatibility only.
alias bool equals_t; //For backwards compatibility only.

alias immutable(char)[]  string;
alias immutable(wchar)[] wstring;
alias immutable(dchar)[] dstring;

/**
 * All D class objects inherit from Object.
 */
class Object
{
    /**
     * Convert Object to a human readable string.
     */
    string toString()
    {
        return typeid(this).name;
    }

    /**
     * Compute hash function for Object.
     */
    size_t toHash() @trusted nothrow
    {
        // BUG: this prevents a compacting GC from working, needs to be fixed
        return cast(size_t)cast(void*)this;
    }

    /**
     * Compare with another Object obj.
     * Returns:
     *  $(TABLE
     *  $(TR $(TD this &lt; obj) $(TD &lt; 0))
     *  $(TR $(TD this == obj) $(TD 0))
     *  $(TR $(TD this &gt; obj) $(TD &gt; 0))
     *  )
     */
    int opCmp(Object o)
    {
        // BUG: this prevents a compacting GC from working, needs to be fixed
        //return cast(int)cast(void*)this - cast(int)cast(void*)o;

        throw new Exception("need opCmp for class " ~ typeid(this).name);
        //return this !is o;
    }

    /**
     * Returns !=0 if this object does have the same contents as obj.
     */
    bool opEquals(Object o)
    {
        return this is o;
    }

    interface Monitor
    {
        void lock();
        void unlock();
    }

    /**
     * Create instance of class specified by the fully qualified name
     * classname.
     * The class must either have no constructors or have
     * a default constructor.
     * Returns:
     *   null if failed
     * Example:
     * ---
     * module foo.bar;
     *
     * class C
     * {
     *     this() { x = 10; }
     *     int x;
     * }
     *
     * void main()
     * {
     *     auto c = cast(C)Object.factory("foo.bar.C");
     *     assert(c !is null && c.x == 10);
     * }
     * ---
     */
    static Object factory(string classname)
    {
        auto ci = TypeInfo_Class.find(classname);
        if (ci)
        {
            return ci.create();
        }
        return null;
    }
}

auto opEquals(Object lhs, Object rhs)
{
    // If aliased to the same object or both null => equal
    if (lhs is rhs) return true;

    // If either is null => non-equal
    if (lhs is null || rhs is null) return false;

    // If same exact type => one call to method opEquals
    if (typeid(lhs) is typeid(rhs) ||
        !__ctfe && typeid(lhs).opEquals(typeid(rhs)))
            /* CTFE doesn't like typeid much. 'is' works, but opEquals doesn't
            (issue 7147). But CTFE also guarantees that equal TypeInfos are
            always identical. So, no opEquals needed during CTFE. */
    {
        return lhs.opEquals(rhs);
    }

    // General case => symmetric calls to method opEquals
    return lhs.opEquals(rhs) && rhs.opEquals(lhs);
}

/************************
* Returns true if lhs and rhs are equal.
*/
auto opEquals(const Object lhs, const Object rhs)
{
    // A hack for the moment.
    return opEquals(cast()lhs, cast()rhs);
}

private extern(C) void _d_setSameMutex(shared Object ownee, shared Object owner) nothrow;

void setSameMutex(shared Object ownee, shared Object owner)
{
    _d_setSameMutex(ownee, owner);
}

/**
 * Information about an interface.
 * When an object is accessed via an interface, an Interface* appears as the
 * first entry in its vtbl.
 */
struct Interface
{
    TypeInfo_Class   classinfo;  /// .classinfo for this interface (not for containing class)
    void*[]     vtbl;
    size_t      offset;     /// offset to Interface 'this' from Object 'this'
}

/**
 * Array of pairs giving the offset and type information for each
 * member in an aggregate.
 */
struct OffsetTypeInfo
{
    size_t   offset;    /// Offset of member from start of object
    TypeInfo ti;        /// TypeInfo for this member
}

/**
 * Runtime type information about a type.
 * Can be retrieved for any type using a
 * <a href="../expression.html#typeidexpression">TypeidExpression</a>.
 */
class TypeInfo
{
    override string toString() const pure @safe nothrow
    {
        return typeid(this).name;
    }

    override size_t toHash() @trusted const
    {
        import core.internal.traits : externDFunc;
        alias hashOf = externDFunc!("rt.util.hash.hashOf",
                                    size_t function(const(void)*, size_t, size_t) @trusted pure nothrow);
        try
        {
            auto data = this.toString();
            return hashOf(data.ptr, data.length, 0);
        }
        catch (Throwable)
        {
            // This should never happen; remove when toString() is made nothrow

            // BUG: this prevents a compacting GC from working, needs to be fixed
            return cast(size_t)cast(void*)this;
        }
    }

    override int opCmp(Object o)
    {
        import core.internal.traits : externDFunc;
        alias dstrcmp = externDFunc!("rt.util.string.dstrcmp",
                                     int function(in char[] s1, in char[] s2) @trusted pure nothrow);

        if (this is o)
            return 0;
        TypeInfo ti = cast(TypeInfo)o;
        if (ti is null)
            return 1;
        return dstrcmp(this.toString(), ti.toString());
    }

    override bool opEquals(Object o)
    {
        /* TypeInfo instances are singletons, but duplicates can exist
         * across DLL's. Therefore, comparing for a name match is
         * sufficient.
         */
        if (this is o)
            return true;
        auto ti = cast(const TypeInfo)o;
        return ti && this.toString() == ti.toString();
    }

    /// Returns a hash of the instance of a type.
    size_t getHash(in void* p) @trusted nothrow const { return cast(size_t)p; }

    /// Compares two instances for equality.
    bool equals(in void* p1, in void* p2) const { return p1 == p2; }

    /// Compares two instances for &lt;, ==, or &gt;.
    int compare(in void* p1, in void* p2) const { return _xopCmp(p1, p2); }

    /// Returns size of the type.
    @property size_t tsize() nothrow pure const @safe @nogc { return 0; }

    /// Swaps two instances of the type.
    void swap(void* p1, void* p2) const
    {
        size_t n = tsize;
        for (size_t i = 0; i < n; i++)
        {
            byte t = (cast(byte *)p1)[i];
            (cast(byte*)p1)[i] = (cast(byte*)p2)[i];
            (cast(byte*)p2)[i] = t;
        }
    }

    /// Get TypeInfo for 'next' type, as defined by what kind of type this is,
    /// null if none.
    @property inout(TypeInfo) next() nothrow pure inout @nogc { return null; }

    /// Return default initializer.  If the type should be initialized to all zeros,
    /// an array with a null ptr and a length equal to the type size will be returned.
    // TODO: make this a property, but may need to be renamed to diambiguate with T.init...
    const(void)[] init() nothrow pure const @safe @nogc { return null; }

    /// Get flags for type: 1 means GC should scan for pointers,
    /// 2 means arg of this type is passed in XMM register
    @property uint flags() nothrow pure const @safe @nogc { return 0; }

    /// Get type information on the contents of the type; null if not available
    const(OffsetTypeInfo)[] offTi() const { return null; }
    /// Run the destructor on the object and all its sub-objects
    void destroy(void* p) const {}
    /// Run the postblit on the object and all its sub-objects
    void postblit(void* p) const {}


    /// Return alignment of type
    @property size_t talign() nothrow pure const @safe @nogc { return tsize; }

    /** Return internal info on arguments fitting into 8byte.
     * See X86-64 ABI 3.2.3
     */
    version (X86_64) int argTypes(out TypeInfo arg1, out TypeInfo arg2) @safe nothrow
    {
        arg1 = this;
        return 0;
    }

    /** Return info used by the garbage collector to do precise collection.
     */
    @property immutable(void)* rtInfo() nothrow pure const @safe @nogc { return null; }
}

class TypeInfo_Typedef : TypeInfo
{
    override string toString() const { return name; }

    override bool opEquals(Object o)
    {
        if (this is o)
            return true;
        auto c = cast(const TypeInfo_Typedef)o;
        return c && this.name == c.name &&
                    this.base == c.base;
    }

    override size_t getHash(in void* p) const { return base.getHash(p); }
    override bool equals(in void* p1, in void* p2) const { return base.equals(p1, p2); }
    override int compare(in void* p1, in void* p2) const { return base.compare(p1, p2); }
    override @property size_t tsize() nothrow pure const { return base.tsize; }
    override void swap(void* p1, void* p2) const { return base.swap(p1, p2); }

    override @property inout(TypeInfo) next() nothrow pure inout { return base.next; }
    override @property uint flags() nothrow pure const { return base.flags; }
    override const(void)[] init() nothrow pure const @safe { return m_init.length ? m_init : base.init(); }

    override @property size_t talign() nothrow pure const { return base.talign; }

    version (X86_64) override int argTypes(out TypeInfo arg1, out TypeInfo arg2)
    {
        return base.argTypes(arg1, arg2);
    }

    override @property immutable(void)* rtInfo() const { return base.rtInfo; }

    TypeInfo base;
    string   name;
    void[]   m_init;
}

class TypeInfo_Enum : TypeInfo_Typedef
{

}

// Please make sure to keep this in sync with TypeInfo_P (src/rt/typeinfo/ti_ptr.d)
class TypeInfo_Pointer : TypeInfo
{
    override string toString() const { return m_next.toString() ~ "*"; }

    override bool opEquals(Object o)
    {
        if (this is o)
            return true;
        auto c = cast(const TypeInfo_Pointer)o;
        return c && this.m_next == c.m_next;
    }

    override size_t getHash(in void* p) @trusted const
    {
        return cast(size_t)*cast(void**)p;
    }

    override bool equals(in void* p1, in void* p2) const
    {
        return *cast(void**)p1 == *cast(void**)p2;
    }

    override int compare(in void* p1, in void* p2) const
    {
        if (*cast(void**)p1 < *cast(void**)p2)
            return -1;
        else if (*cast(void**)p1 > *cast(void**)p2)
            return 1;
        else
            return 0;
    }

    override @property size_t tsize() nothrow pure const
    {
        return (void*).sizeof;
    }

    override void swap(void* p1, void* p2) const
    {
        void* tmp = *cast(void**)p1;
        *cast(void**)p1 = *cast(void**)p2;
        *cast(void**)p2 = tmp;
    }

    override @property inout(TypeInfo) next() nothrow pure inout { return m_next; }
    override @property uint flags() nothrow pure const { return 1; }

    TypeInfo m_next;
}

class TypeInfo_Array : TypeInfo
{
    override string toString() const { return value.toString() ~ "[]"; }

    override bool opEquals(Object o)
    {
        if (this is o)
            return true;
        auto c = cast(const TypeInfo_Array)o;
        return c && this.value == c.value;
    }

    override size_t getHash(in void* p) @trusted const
    {
        void[] a = *cast(void[]*)p;
        return getArrayHash(value, a.ptr, a.length);
    }

    override bool equals(in void* p1, in void* p2) const
    {
        void[] a1 = *cast(void[]*)p1;
        void[] a2 = *cast(void[]*)p2;
        if (a1.length != a2.length)
            return false;
        size_t sz = value.tsize;
        for (size_t i = 0; i < a1.length; i++)
        {
            if (!value.equals(a1.ptr + i * sz, a2.ptr + i * sz))
                return false;
        }
        return true;
    }

    override int compare(in void* p1, in void* p2) const
    {
        void[] a1 = *cast(void[]*)p1;
        void[] a2 = *cast(void[]*)p2;
        size_t sz = value.tsize;
        size_t len = a1.length;

        if (a2.length < len)
            len = a2.length;
        for (size_t u = 0; u < len; u++)
        {
            int result = value.compare(a1.ptr + u * sz, a2.ptr + u * sz);
            if (result)
                return result;
        }
        return cast(int)a1.length - cast(int)a2.length;
    }

    override @property size_t tsize() nothrow pure const
    {
        return (void[]).sizeof;
    }

    override void swap(void* p1, void* p2) const
    {
        void[] tmp = *cast(void[]*)p1;
        *cast(void[]*)p1 = *cast(void[]*)p2;
        *cast(void[]*)p2 = tmp;
    }

    TypeInfo value;

    override @property inout(TypeInfo) next() nothrow pure inout
    {
        return value;
    }

    override @property uint flags() nothrow pure const { return 1; }

    override @property size_t talign() nothrow pure const
    {
        return (void[]).alignof;
    }

    version (X86_64) override int argTypes(out TypeInfo arg1, out TypeInfo arg2)
    {
        arg1 = typeid(size_t);
        arg2 = typeid(void*);
        return 0;
    }
}

class TypeInfo_StaticArray : TypeInfo
{
    override string toString() const
    {
        import core.internal.traits : externDFunc;
        alias sizeToTempString = externDFunc!("rt.util.string.sizeToTempString",
                                              char[] function(in size_t, char[]) @trusted pure nothrow);

        char[20] tmpBuff = void;
        return value.toString() ~ "[" ~ sizeToTempString(len, tmpBuff) ~ "]";
    }

    override bool opEquals(Object o)
    {
        if (this is o)
            return true;
        auto c = cast(const TypeInfo_StaticArray)o;
        return c && this.len == c.len &&
                    this.value == c.value;
    }

    override size_t getHash(in void* p) @trusted const
    {
        return getArrayHash(value, p, len);
    }

    override bool equals(in void* p1, in void* p2) const
    {
        size_t sz = value.tsize;

        for (size_t u = 0; u < len; u++)
        {
            if (!value.equals(p1 + u * sz, p2 + u * sz))
                return false;
        }
        return true;
    }

    override int compare(in void* p1, in void* p2) const
    {
        size_t sz = value.tsize;

        for (size_t u = 0; u < len; u++)
        {
            int result = value.compare(p1 + u * sz, p2 + u * sz);
            if (result)
                return result;
        }
        return 0;
    }

    override @property size_t tsize() nothrow pure const
    {
        return len * value.tsize;
    }

    override void swap(void* p1, void* p2) const
    {
        import core.memory;
        import core.stdc.string : memcpy;

        void* tmp;
        size_t sz = value.tsize;
        ubyte[16] buffer;
        void* pbuffer;

        if (sz < buffer.sizeof)
            tmp = buffer.ptr;
        else
            tmp = pbuffer = (new void[sz]).ptr;

        for (size_t u = 0; u < len; u += sz)
        {
            size_t o = u * sz;
            memcpy(tmp, p1 + o, sz);
            memcpy(p1 + o, p2 + o, sz);
            memcpy(p2 + o, tmp, sz);
        }
        if (pbuffer)
            GC.free(pbuffer);
    }

    override const(void)[] init() nothrow pure const { return value.init(); }
    override @property inout(TypeInfo) next() nothrow pure inout { return value; }
    override @property uint flags() nothrow pure const { return value.flags; }

    override void destroy(void* p) const
    {
        auto sz = value.tsize;
        p += sz * len;
        foreach (i; 0 .. len)
        {
            p -= sz;
            value.destroy(p);
        }
    }

    override void postblit(void* p) const
    {
        auto sz = value.tsize;
        foreach (i; 0 .. len)
        {
            value.postblit(p);
            p += sz;
        }
    }

    TypeInfo value;
    size_t   len;

    override @property size_t talign() nothrow pure const
    {
        return value.talign;
    }

    version (X86_64) override int argTypes(out TypeInfo arg1, out TypeInfo arg2)
    {
        arg1 = typeid(void*);
        return 0;
    }
}

class TypeInfo_AssociativeArray : TypeInfo
{
    override string toString() const
    {
        return value.toString() ~ "[" ~ key.toString() ~ "]";
    }

    override bool opEquals(Object o)
    {
        if (this is o)
            return true;
        auto c = cast(const TypeInfo_AssociativeArray)o;
        return c && this.key == c.key &&
                    this.value == c.value;
    }

    override bool equals(in void* p1, in void* p2) @trusted const
    {
        return !!_aaEqual(this, *cast(const void**) p1, *cast(const void**) p2);
    }

    override hash_t getHash(in void* p) nothrow @trusted const
    {
        return _aaGetHash(cast(void*)p, this);
    }

    // BUG: need to add the rest of the functions

    override @property size_t tsize() nothrow pure const
    {
        return (char[int]).sizeof;
    }

    override @property inout(TypeInfo) next() nothrow pure inout { return value; }
    override @property uint flags() nothrow pure const { return 1; }

    TypeInfo value;
    TypeInfo key;

    override @property size_t talign() nothrow pure const
    {
        return (char[int]).alignof;
    }

    version (X86_64) override int argTypes(out TypeInfo arg1, out TypeInfo arg2)
    {
        arg1 = typeid(void*);
        return 0;
    }
}

class TypeInfo_Vector : TypeInfo
{
    override string toString() const { return "__vector(" ~ base.toString() ~ ")"; }

    override bool opEquals(Object o)
    {
        if (this is o)
            return true;
        auto c = cast(const TypeInfo_Vector)o;
        return c && this.base == c.base;
    }

    override size_t getHash(in void* p) const { return base.getHash(p); }
    override bool equals(in void* p1, in void* p2) const { return base.equals(p1, p2); }
    override int compare(in void* p1, in void* p2) const { return base.compare(p1, p2); }
    override @property size_t tsize() nothrow pure const { return base.tsize; }
    override void swap(void* p1, void* p2) const { return base.swap(p1, p2); }

    override @property inout(TypeInfo) next() nothrow pure inout { return base.next; }
    override @property uint flags() nothrow pure const { return base.flags; }
    override const(void)[] init() nothrow pure const { return base.init(); }

    override @property size_t talign() nothrow pure const { return 16; }

    version (X86_64) override int argTypes(out TypeInfo arg1, out TypeInfo arg2)
    {
        return base.argTypes(arg1, arg2);
    }

    TypeInfo base;
}

class TypeInfo_Function : TypeInfo
{
    override string toString() const
    {
        return cast(string)(next.toString() ~ "()");
    }

    override bool opEquals(Object o)
    {
        if (this is o)
            return true;
        auto c = cast(const TypeInfo_Function)o;
        return c && this.deco == c.deco;
    }

    // BUG: need to add the rest of the functions

    override @property size_t tsize() nothrow pure const
    {
        return 0;       // no size for functions
    }

    TypeInfo next;
    string deco;
}

class TypeInfo_Delegate : TypeInfo
{
    override string toString() const
    {
        return cast(string)(next.toString() ~ " delegate()");
    }

    override bool opEquals(Object o)
    {
        if (this is o)
            return true;
        auto c = cast(const TypeInfo_Delegate)o;
        return c && this.deco == c.deco;
    }

    // BUG: need to add the rest of the functions

    override @property size_t tsize() nothrow pure const
    {
        alias int delegate() dg;
        return dg.sizeof;
    }

    override @property uint flags() nothrow pure const { return 1; }

    TypeInfo next;
    string deco;

    override @property size_t talign() nothrow pure const
    {
        alias int delegate() dg;
        return dg.alignof;
    }

    version (X86_64) override int argTypes(out TypeInfo arg1, out TypeInfo arg2)
    {
        arg1 = typeid(void*);
        arg2 = typeid(void*);
        return 0;
    }
}

/**
 * Runtime type information about a class.
 * Can be retrieved from an object instance by using the
 * $(LINK2 ../property.html#classinfo, .classinfo) property.
 */
class TypeInfo_Class : TypeInfo
{
    override string toString() const { return info.name; }

    override bool opEquals(Object o)
    {
        if (this is o)
            return true;
        auto c = cast(const TypeInfo_Class)o;
        return c && this.info.name == c.info.name;
    }

    override size_t getHash(in void* p) @trusted const
    {
        auto o = *cast(Object*)p;
        return o ? o.toHash() : 0;
    }

    override bool equals(in void* p1, in void* p2) const
    {
        Object o1 = *cast(Object*)p1;
        Object o2 = *cast(Object*)p2;

        return (o1 is o2) || (o1 && o1.opEquals(o2));
    }

    override int compare(in void* p1, in void* p2) const
    {
        Object o1 = *cast(Object*)p1;
        Object o2 = *cast(Object*)p2;
        int c = 0;

        // Regard null references as always being "less than"
        if (o1 !is o2)
        {
            if (o1)
            {
                if (!o2)
                    c = 1;
                else
                    c = o1.opCmp(o2);
            }
            else
                c = -1;
        }
        return c;
    }

    override @property size_t tsize() nothrow pure const
    {
        return Object.sizeof;
    }

    override const(void)[] init() nothrow pure const @safe { return m_init; }

    override @property uint flags() nothrow pure const { return 1; }

    override @property const(OffsetTypeInfo)[] offTi() nothrow pure const
    {
        return m_offTi;
    }

    @property auto info() @safe nothrow pure const { return this; }
    @property auto typeinfo() @safe nothrow pure const { return this; }

    byte[]      m_init;         /** class static initializer
                                 * (init.length gives size in bytes of class)
                                 */
    string      name;           /// class name
    void*[]     vtbl;           /// virtual function pointer table
    Interface[] interfaces;     /// interfaces this class implements
    TypeInfo_Class   base;           /// base class
    void*       destructor;
    void function(Object) classInvariant;
    enum ClassFlags : uint
    {
        isCOMclass = 0x1,
        noPointers = 0x2,
        hasOffTi = 0x4,
        hasCtor = 0x8,
        hasGetMembers = 0x10,
        hasTypeInfo = 0x20,
        isAbstract = 0x40,
        isCPPclass = 0x80,
        hasDtor = 0x100,
    }
    ClassFlags m_flags;
    void*       deallocator;
    OffsetTypeInfo[] m_offTi;
    void function(Object) defaultConstructor;   // default Constructor

    immutable(void)* m_RTInfo;        // data for precise GC
    override @property immutable(void)* rtInfo() const { return m_RTInfo; }

    /**
     * Search all modules for TypeInfo_Class corresponding to classname.
     * Returns: null if not found
     */
    static const(TypeInfo_Class) find(in char[] classname)
    {
        foreach (m; ModuleInfo)
        {
          if (m)
            //writefln("module %s, %d", m.name, m.localClasses.length);
            foreach (c; m.localClasses)
            {
                if (c is null) continue;
                //writefln("\tclass %s", c.name);
                if (c.name == classname)
                    return c;
            }
        }
        return null;
    }

    /**
     * Create instance of Object represented by 'this'.
     */
    Object create() const
    {
        if (m_flags & 8 && !defaultConstructor)
            return null;
        if (m_flags & 64) // abstract
            return null;
        Object o = _d_newclass(this);
        if (m_flags & 8 && defaultConstructor)
        {
            defaultConstructor(o);
        }
        return o;
    }
}

alias TypeInfo_Class ClassInfo;

unittest
{
    // Bugzilla 14401
    static class X
    {
        int a;
    }

    assert(typeid(X).init is typeid(X).m_init);
    assert(typeid(X).init.length == typeid(const(X)).init.length);
    assert(typeid(X).init.length == typeid(shared(X)).init.length);
    assert(typeid(X).init.length == typeid(immutable(X)).init.length);
}

class TypeInfo_Interface : TypeInfo
{
    override string toString() const { return info.name; }

    override bool opEquals(Object o)
    {
        if (this is o)
            return true;
        auto c = cast(const TypeInfo_Interface)o;
        return c && this.info.name == typeid(c).name;
    }

    override size_t getHash(in void* p) @trusted const
    {
        Interface* pi = **cast(Interface ***)*cast(void**)p;
        Object o = cast(Object)(*cast(void**)p - pi.offset);
        assert(o);
        return o.toHash();
    }

    override bool equals(in void* p1, in void* p2) const
    {
        Interface* pi = **cast(Interface ***)*cast(void**)p1;
        Object o1 = cast(Object)(*cast(void**)p1 - pi.offset);
        pi = **cast(Interface ***)*cast(void**)p2;
        Object o2 = cast(Object)(*cast(void**)p2 - pi.offset);

        return o1 == o2 || (o1 && o1.opCmp(o2) == 0);
    }

    override int compare(in void* p1, in void* p2) const
    {
        Interface* pi = **cast(Interface ***)*cast(void**)p1;
        Object o1 = cast(Object)(*cast(void**)p1 - pi.offset);
        pi = **cast(Interface ***)*cast(void**)p2;
        Object o2 = cast(Object)(*cast(void**)p2 - pi.offset);
        int c = 0;

        // Regard null references as always being "less than"
        if (o1 != o2)
        {
            if (o1)
            {
                if (!o2)
                    c = 1;
                else
                    c = o1.opCmp(o2);
            }
            else
                c = -1;
        }
        return c;
    }

    override @property size_t tsize() nothrow pure const
    {
        return Object.sizeof;
    }

    override @property uint flags() nothrow pure const { return 1; }

    TypeInfo_Class info;
}

class TypeInfo_Struct : TypeInfo
{
    override string toString() const { return name; }

    override bool opEquals(Object o)
    {
        if (this is o)
            return true;
        auto s = cast(const TypeInfo_Struct)o;
        return s && this.name == s.name &&
                    this.init().length == s.init().length;
    }

    override size_t getHash(in void* p) @safe pure nothrow const
    {
        assert(p);
        if (xtoHash)
        {
            return (*xtoHash)(p);
        }
        else
        {
            import core.internal.traits : externDFunc;
            alias hashOf = externDFunc!("rt.util.hash.hashOf",
                                        size_t function(const(void)*, size_t, size_t) @trusted pure nothrow);
            return hashOf(p, init().length, 0);
        }
    }

    override bool equals(in void* p1, in void* p2) @trusted pure nothrow const
    {
        import core.stdc.string : memcmp;

        if (!p1 || !p2)
            return false;
        else if (xopEquals)
            return (*xopEquals)(p1, p2);
        else if (p1 == p2)
            return true;
        else
            // BUG: relies on the GC not moving objects
            return memcmp(p1, p2, init().length) == 0;
    }

    override int compare(in void* p1, in void* p2) @trusted pure nothrow const
    {
        import core.stdc.string : memcmp;

        // Regard null references as always being "less than"
        if (p1 != p2)
        {
            if (p1)
            {
                if (!p2)
                    return true;
                else if (xopCmp)
                    return (*xopCmp)(p2, p1);
                else
                    // BUG: relies on the GC not moving objects
                    return memcmp(p1, p2, init().length);
            }
            else
                return -1;
        }
        return 0;
    }

    override @property size_t tsize() nothrow pure const
    {
        return init().length;
    }

    override const(void)[] init() nothrow pure const @safe { return m_init; }

    override @property uint flags() nothrow pure const { return m_flags; }

    override @property size_t talign() nothrow pure const { return m_align; }

    final override void destroy(void* p) const
    {
        if (xdtor)
        {
            if (m_flags & StructFlags.isDynamicType)
                (*xdtorti)(p, this);
            else
                (*xdtor)(p);
        }
    }

    override void postblit(void* p) const
    {
        if (xpostblit)
            (*xpostblit)(p);
    }

    string name;
    void[] m_init;      // initializer; init.ptr == null if 0 initialize

  @safe pure nothrow
  {
    size_t   function(in void*)           xtoHash;
    bool     function(in void*, in void*) xopEquals;
    int      function(in void*, in void*) xopCmp;
    string   function(in void*)           xtoString;

    enum StructFlags : uint
    {
        hasPointers = 0x1,
        isDynamicType = 0x2, // built at runtime, needs type info in xdtor
    }
    StructFlags m_flags;
  }
    union
    {
        void function(void*)                xdtor;
        void function(void*, const TypeInfo_Struct ti) xdtorti;
    }
    void function(void*)                    xpostblit;

    uint m_align;

    override @property immutable(void)* rtInfo() const { return m_RTInfo; }

    version (X86_64)
    {
        override int argTypes(out TypeInfo arg1, out TypeInfo arg2)
        {
            arg1 = m_arg1;
            arg2 = m_arg2;
            return 0;
        }
        TypeInfo m_arg1;
        TypeInfo m_arg2;
    }
    immutable(void)* m_RTInfo;                // data for precise GC
}

unittest
{
    struct S
    {
        bool opEquals(ref const S rhs) const
        {
            return false;
        }
    }
    S s;
    assert(!typeid(S).equals(&s, &s));
}

class TypeInfo_Tuple : TypeInfo
{
    TypeInfo[] elements;

    override string toString() const
    {
        string s = "(";
        foreach (i, element; elements)
        {
            if (i)
                s ~= ',';
            s ~= element.toString();
        }
        s ~= ")";
        return s;
    }

    override bool opEquals(Object o)
    {
        if (this is o)
            return true;

        auto t = cast(const TypeInfo_Tuple)o;
        if (t && elements.length == t.elements.length)
        {
            for (size_t i = 0; i < elements.length; i++)
            {
                if (elements[i] != t.elements[i])
                    return false;
            }
            return true;
        }
        return false;
    }

    override size_t getHash(in void* p) const
    {
        assert(0);
    }

    override bool equals(in void* p1, in void* p2) const
    {
        assert(0);
    }

    override int compare(in void* p1, in void* p2) const
    {
        assert(0);
    }

    override @property size_t tsize() nothrow pure const
    {
        assert(0);
    }

    override void swap(void* p1, void* p2) const
    {
        assert(0);
    }

    override void destroy(void* p) const
    {
        assert(0);
    }

    override void postblit(void* p) const
    {
        assert(0);
    }

    override @property size_t talign() nothrow pure const
    {
        assert(0);
    }

    version (X86_64) override int argTypes(out TypeInfo arg1, out TypeInfo arg2)
    {
        assert(0);
    }
}

class TypeInfo_Const : TypeInfo
{
    override string toString() const
    {
        return cast(string) ("const(" ~ base.toString() ~ ")");
    }

    //override bool opEquals(Object o) { return base.opEquals(o); }
    override bool opEquals(Object o)
    {
        if (this is o)
            return true;

        if (typeid(this) != typeid(o))
            return false;

        auto t = cast(TypeInfo_Const)o;
        return base.opEquals(t.base);
    }

    override size_t getHash(in void *p) const { return base.getHash(p); }
    override bool equals(in void *p1, in void *p2) const { return base.equals(p1, p2); }
    override int compare(in void *p1, in void *p2) const { return base.compare(p1, p2); }
    override @property size_t tsize() nothrow pure const { return base.tsize; }
    override void swap(void *p1, void *p2) const { return base.swap(p1, p2); }

    override @property inout(TypeInfo) next() nothrow pure inout { return base.next; }
    override @property uint flags() nothrow pure const { return base.flags; }
    override const(void)[] init() nothrow pure const { return base.init(); }

    override @property size_t talign() nothrow pure const { return base.talign; }

    version (X86_64) override int argTypes(out TypeInfo arg1, out TypeInfo arg2)
    {
        return base.argTypes(arg1, arg2);
    }

    TypeInfo base;
}

class TypeInfo_Invariant : TypeInfo_Const
{
    override string toString() const
    {
        return cast(string) ("immutable(" ~ base.toString() ~ ")");
    }
}

class TypeInfo_Shared : TypeInfo_Const
{
    override string toString() const
    {
        return cast(string) ("shared(" ~ base.toString() ~ ")");
    }
}

class TypeInfo_Inout : TypeInfo_Const
{
    override string toString() const
    {
        return cast(string) ("inout(" ~ base.toString() ~ ")");
    }
}


///////////////////////////////////////////////////////////////////////////////
// ModuleInfo
///////////////////////////////////////////////////////////////////////////////


enum
{
    MIctorstart  = 0x1,   // we've started constructing it
    MIctordone   = 0x2,   // finished construction
    MIstandalone = 0x4,   // module ctor does not depend on other module
                        // ctors being done first
    MItlsctor    = 8,
    MItlsdtor    = 0x10,
    MIctor       = 0x20,
    MIdtor       = 0x40,
    MIxgetMembers = 0x80,
    MIictor      = 0x100,
    MIunitTest   = 0x200,
    MIimportedModules = 0x400,
    MIlocalClasses = 0x800,
    MIname       = 0x1000,
}


struct ModuleInfo
{
    uint _flags;
    uint _index; // index into _moduleinfo_array[]

    version (all)
    {
        deprecated("ModuleInfo cannot be copy-assigned because it is a variable-sized struct.")
        void opAssign(in ModuleInfo m) { _flags = m._flags; _index = m._index; }
    }
    else
    {
        @disable this();
        @disable this(this) const;
    }

const:
    private void* addrOf(int flag) nothrow pure
    in
    {
        assert(flag >= MItlsctor && flag <= MIname);
        assert(!(flag & (flag - 1)) && !(flag & ~(flag - 1) << 1));
    }
    body
    {
        import core.stdc.string : strlen;

        void* p = cast(void*)&this + ModuleInfo.sizeof;

        if (flags & MItlsctor)
        {
            if (flag == MItlsctor) return p;
            p += typeof(tlsctor).sizeof;
        }
        if (flags & MItlsdtor)
        {
            if (flag == MItlsdtor) return p;
            p += typeof(tlsdtor).sizeof;
        }
        if (flags & MIctor)
        {
            if (flag == MIctor) return p;
            p += typeof(ctor).sizeof;
        }
        if (flags & MIdtor)
        {
            if (flag == MIdtor) return p;
            p += typeof(dtor).sizeof;
        }
        if (flags & MIxgetMembers)
        {
            if (flag == MIxgetMembers) return p;
            p += typeof(xgetMembers).sizeof;
        }
        if (flags & MIictor)
        {
            if (flag == MIictor) return p;
            p += typeof(ictor).sizeof;
        }
        if (flags & MIunitTest)
        {
            if (flag == MIunitTest) return p;
            p += typeof(unitTest).sizeof;
        }
        if (flags & MIimportedModules)
        {
            if (flag == MIimportedModules) return p;
            p += size_t.sizeof + *cast(size_t*)p * typeof(importedModules[0]).sizeof;
        }
        if (flags & MIlocalClasses)
        {
            if (flag == MIlocalClasses) return p;
            p += size_t.sizeof + *cast(size_t*)p * typeof(localClasses[0]).sizeof;
        }
        if (true || flags & MIname) // always available for now
        {
            if (flag == MIname) return p;
            p += strlen(cast(immutable char*)p);
        }
        assert(0);
    }

    @property uint index() nothrow pure { return _index; }

    @property uint flags() nothrow pure { return _flags; }

    @property void function() tlsctor() nothrow pure
    {
        return flags & MItlsctor ? *cast(typeof(return)*)addrOf(MItlsctor) : null;
    }

    @property void function() tlsdtor() nothrow pure
    {
        return flags & MItlsdtor ? *cast(typeof(return)*)addrOf(MItlsdtor) : null;
    }

    @property void* xgetMembers() nothrow pure
    {
        return flags & MIxgetMembers ? *cast(typeof(return)*)addrOf(MIxgetMembers) : null;
    }

    @property void function() ctor() nothrow pure
    {
        return flags & MIctor ? *cast(typeof(return)*)addrOf(MIctor) : null;
    }

    @property void function() dtor() nothrow pure
    {
        return flags & MIdtor ? *cast(typeof(return)*)addrOf(MIdtor) : null;
    }

    @property void function() ictor() nothrow pure
    {
        return flags & MIictor ? *cast(typeof(return)*)addrOf(MIictor) : null;
    }

    @property void function() unitTest() nothrow pure
    {
        return flags & MIunitTest ? *cast(typeof(return)*)addrOf(MIunitTest) : null;
    }

    @property immutable(ModuleInfo*)[] importedModules() nothrow pure
    {
        if (flags & MIimportedModules)
        {
            auto p = cast(size_t*)addrOf(MIimportedModules);
            return (cast(immutable(ModuleInfo*)*)(p + 1))[0 .. *p];
        }
        return null;
    }

    @property TypeInfo_Class[] localClasses() nothrow pure
    {
        if (flags & MIlocalClasses)
        {
            auto p = cast(size_t*)addrOf(MIlocalClasses);
            return (cast(TypeInfo_Class*)(p + 1))[0 .. *p];
        }
        return null;
    }

    @property string name() nothrow pure
    {
        if (true || flags & MIname) // always available for now
        {
            import core.stdc.string : strlen;

            auto p = cast(immutable char*)addrOf(MIname);
            return p[0 .. strlen(p)];
        }
        // return null;
    }

    static int opApply(scope int delegate(ModuleInfo*) dg)
    {
        import rt.minfo;
        // Bugzilla 13084 - enforcing immutable ModuleInfo would break client code
        return rt.minfo.moduleinfos_apply(
            (immutable(ModuleInfo*)m) => dg(cast(ModuleInfo*)m));
    }
}

unittest
{
    ModuleInfo* m1;
    foreach (m; ModuleInfo)
    {
        m1 = m;
    }
}

///////////////////////////////////////////////////////////////////////////////
// Throwable
///////////////////////////////////////////////////////////////////////////////


/**
 * The base class of all thrown objects.
 *
 * All thrown objects must inherit from Throwable. Class $(D Exception), which
 * derives from this class, represents the category of thrown objects that are
 * safe to catch and handle. In principle, one should not catch Throwable
 * objects that are not derived from $(D Exception), as they represent
 * unrecoverable runtime errors. Certain runtime guarantees may fail to hold
 * when these errors are thrown, making it unsafe to continue execution after
 * catching them.
 */
class Throwable : Object
{
    interface TraceInfo
    {
        int opApply(scope int delegate(ref const(char[]))) const;
        int opApply(scope int delegate(ref size_t, ref const(char[]))) const;
        string toString() const;
    }

    string      msg;    /// A message describing the error.

    /**
     * The _file name and line number of the D source code corresponding with
     * where the error was thrown from.
     */
    string      file;
    size_t      line;   /// ditto

    /**
     * The stack trace of where the error happened. This is an opaque object
     * that can either be converted to $(D string), or iterated over with $(D
     * foreach) to extract the items in the stack trace (as strings).
     */
    TraceInfo   info;

    /**
     * A reference to the _next error in the list. This is used when a new
     * $(D Throwable) is thrown from inside a $(D catch) block. The originally
     * caught $(D Exception) will be chained to the new $(D Throwable) via this
     * field.
     */
    Throwable   next;

    @nogc @safe pure nothrow this(string msg, Throwable next = null)
    {
        this.msg = msg;
        this.next = next;
        //this.info = _d_traceContext();
    }

    @nogc @safe pure nothrow this(string msg, string file, size_t line, Throwable next = null)
    {
        this(msg, next);
        this.file = file;
        this.line = line;
        //this.info = _d_traceContext();
    }

    /**
     * Overrides $(D Object.toString) and returns the error message.
     * Internally this forwards to the $(D toString) overload that
     * takes a $(PARAM sink) delegate.
     */
    override string toString()
    {
        string s;
        toString((buf) { s ~= buf; });
        return s;
    }

    /**
     * The Throwable hierarchy uses a toString overload that takes a
     * $(PARAM sink) delegate to avoid GC allocations, which cannot be
     * performed in certain error situations.  Override this $(D
     * toString) method to customize the error message.
     */
    void toString(scope void delegate(in char[]) sink) const
    {
        import core.internal.traits : externDFunc;
        alias sizeToTempString = externDFunc!("rt.util.string.sizeToTempString",
                                              char[] function(in size_t, char[]) @trusted pure nothrow);

        char[20] tmpBuff = void;

        sink(typeid(this).name);
        sink("@"); sink(file);
        sink("("); sink(sizeToTempString(line, tmpBuff)); sink(")");

        if (msg.length)
        {
            sink(": "); sink(msg);
        }
        if (info)
        {
            try
            {
                sink("\n----------------");
                foreach (t; info)
                {
                    sink("\n"); sink(t);
                }
            }
            catch (Throwable)
            {
                // ignore more errors
            }
        }
    }
}


/**
 * The base class of all errors that are safe to catch and handle.
 *
 * In principle, only thrown objects derived from this class are safe to catch
 * inside a $(D catch) block. Thrown objects not derived from Exception
 * represent runtime errors that should not be caught, as certain runtime
 * guarantees may not hold, making it unsafe to continue program execution.
 */
class Exception : Throwable
{

    /**
     * Creates a new instance of Exception. The next parameter is used
     * internally and should always be $(D null) when passed by user code.
     * This constructor does not automatically throw the newly-created
     * Exception; the $(D throw) statement should be used for that purpose.
     */
    @nogc @safe pure nothrow this(string msg, string file = __FILE__, size_t line = __LINE__, Throwable next = null)
    {
        super(msg, file, line, next);
    }

    @nogc @safe pure nothrow this(string msg, Throwable next, string file = __FILE__, size_t line = __LINE__)
    {
        super(msg, file, line, next);
    }
}

unittest
{
    {
        auto e = new Exception("msg");
        assert(e.file == __FILE__);
        assert(e.line == __LINE__ - 2);
        assert(e.next is null);
        assert(e.msg == "msg");
    }

    {
        auto e = new Exception("msg", new Exception("It's an Excepton!"), "hello", 42);
        assert(e.file == "hello");
        assert(e.line == 42);
        assert(e.next !is null);
        assert(e.msg == "msg");
    }

    {
        auto e = new Exception("msg", "hello", 42, new Exception("It's an Exception!"));
        assert(e.file == "hello");
        assert(e.line == 42);
        assert(e.next !is null);
        assert(e.msg == "msg");
    }
}


/**
 * The base class of all unrecoverable runtime errors.
 *
 * This represents the category of $(D Throwable) objects that are $(B not)
 * safe to catch and handle. In principle, one should not catch Error
 * objects, as they represent unrecoverable runtime errors.
 * Certain runtime guarantees may fail to hold when these errors are
 * thrown, making it unsafe to continue execution after catching them.
 */
class Error : Throwable
{
    /**
     * Creates a new instance of Error. The next parameter is used
     * internally and should always be $(D null) when passed by user code.
     * This constructor does not automatically throw the newly-created
     * Error; the $(D throw) statement should be used for that purpose.
     */
    @nogc @safe pure nothrow this(string msg, Throwable next = null)
    {
        super(msg, next);
        bypassedException = null;
    }

    @nogc @safe pure nothrow this(string msg, string file, size_t line, Throwable next = null)
    {
        super(msg, file, line, next);
        bypassedException = null;
    }

    /// The first $(D Exception) which was bypassed when this Error was thrown,
    /// or $(D null) if no $(D Exception)s were pending.
    Throwable   bypassedException;
}

unittest
{
    {
        auto e = new Error("msg");
        assert(e.file is null);
        assert(e.line == 0);
        assert(e.next is null);
        assert(e.msg == "msg");
        assert(e.bypassedException is null);
    }

    {
        auto e = new Error("msg", new Exception("It's an Excepton!"));
        assert(e.file is null);
        assert(e.line == 0);
        assert(e.next !is null);
        assert(e.msg == "msg");
        assert(e.bypassedException is null);
    }

    {
        auto e = new Error("msg", "hello", 42, new Exception("It's an Exception!"));
        assert(e.file == "hello");
        assert(e.line == 42);
        assert(e.next !is null);
        assert(e.msg == "msg");
        assert(e.bypassedException is null);
    }
}


extern (C)
{
    // from druntime/src/rt/aaA.d

    // size_t _aaLen(in void* p) pure nothrow @nogc;
    private void* _aaGetY(void** paa, const TypeInfo_AssociativeArray ti, in size_t valuesize, in void* pkey) pure nothrow;
    // inout(void)* _aaGetRvalueX(inout void* p, in TypeInfo keyti, in size_t valuesize, in void* pkey);
    inout(void)[] _aaValues(inout void* p, in size_t keysize, in size_t valuesize, const TypeInfo tiValArray) pure nothrow;
    inout(void)[] _aaKeys(inout void* p, in size_t keysize, const TypeInfo tiKeyArray) pure nothrow;
    void* _aaRehash(void** pp, in TypeInfo keyti) pure nothrow;

    // alias _dg_t = extern(D) int delegate(void*);
    // int _aaApply(void* aa, size_t keysize, _dg_t dg);

    // alias _dg2_t = extern(D) int delegate(void*, void*);
    // int _aaApply2(void* aa, size_t keysize, _dg2_t dg);

    private struct AARange { void* impl; size_t idx; }
    AARange _aaRange(void* aa) pure nothrow @nogc;
    bool _aaRangeEmpty(AARange r) pure nothrow @nogc;
    void* _aaRangeFrontKey(AARange r) pure nothrow @nogc;
    void* _aaRangeFrontValue(AARange r) pure nothrow @nogc;
    void _aaRangePopFront(ref AARange r) pure nothrow @nogc;

    int _aaEqual(in TypeInfo tiRaw, in void* e1, in void* e2);
    hash_t _aaGetHash(in void* aa, in TypeInfo tiRaw) nothrow;

    /*
        _d_assocarrayliteralTX marked as pure, because aaLiteral can be called from pure code.
        This is a typesystem hole, however this is existing hole.
        Early compiler didn't check purity of toHash or postblit functions, if key is a UDT thus
        copiler allowed to create AA literal with keys, which have impure unsafe toHash methods.
    */
    void* _d_assocarrayliteralTX(const TypeInfo_AssociativeArray ti, void[] keys, void[] values) pure;
}

void* aaLiteral(Key, Value)(Key[] keys, Value[] values) @trusted pure
{
    return _d_assocarrayliteralTX(typeid(Value[Key]), *cast(void[]*)&keys, *cast(void[]*)&values);
}

alias AssociativeArray(Key, Value) = Value[Key];

T rehash(T : Value[Key], Value, Key)(T aa)
{
    _aaRehash(cast(void**)&aa, typeid(Value[Key]));
    return aa;
}

T rehash(T : Value[Key], Value, Key)(T* aa)
{
    _aaRehash(cast(void**)aa, typeid(Value[Key]));
    return *aa;
}

T rehash(T : shared Value[Key], Value, Key)(T aa)
{
    _aaRehash(cast(void**)&aa, typeid(Value[Key]));
    return aa;
}

T rehash(T : shared Value[Key], Value, Key)(T* aa)
{
    _aaRehash(cast(void**)aa, typeid(Value[Key]));
    return *aa;
}

V[K] dup(T : V[K], K, V)(T aa)
{
    //pragma(msg, "K = ", K, ", V = ", V);

    // Bug10720 - check whether V is copyable
    static assert(is(typeof({ V v = aa[K.init]; })),
        "cannot call " ~ T.stringof ~ ".dup because " ~ V.stringof ~ " is not copyable");

    V[K] result;

    //foreach (k, ref v; aa)
    //    result[k] = v;  // Bug13701 - won't work if V is not mutable

    ref V duplicateElem(ref K k, ref const V v) @trusted pure nothrow
    {
        import core.stdc.string : memcpy;

        void* pv = _aaGetY(cast(void**)&result, typeid(V[K]), V.sizeof, &k);
        memcpy(pv, &v, V.sizeof);
        return *cast(V*)pv;
    }

    if (auto postblit = _getPostblit!V())
    {
        foreach (k, ref v; aa)
            postblit(duplicateElem(k, v));
    }
    else
    {
        foreach (k, ref v; aa)
            duplicateElem(k, v);
    }

    return result;
}

V[K] dup(T : V[K], K, V)(T* aa)
{
    return (*aa).dup;
}

auto byKey(T : V[K], K, V)(T aa) pure nothrow @nogc
{
    import core.internal.traits : substInout;

    static struct Result
    {
        AARange r;

    pure nothrow @nogc:
        @property bool empty() { return _aaRangeEmpty(r); }
        @property ref front() { return *cast(substInout!K*)_aaRangeFrontKey(r); }
        void popFront() { _aaRangePopFront(r); }
        @property Result save() { return this; }
    }

    return Result(_aaRange(cast(void*)aa));
}

auto byKey(T : V[K], K, V)(T* aa) pure nothrow @nogc
{
    return (*aa).byKey();
}

auto byValue(T : V[K], K, V)(T aa) pure nothrow @nogc
{
    import core.internal.traits : substInout;

    static struct Result
    {
        AARange r;

    pure nothrow @nogc:
        @property bool empty() { return _aaRangeEmpty(r); }
        @property ref front() { return *cast(substInout!V*)_aaRangeFrontValue(r); }
        void popFront() { _aaRangePopFront(r); }
        @property Result save() { return this; }
    }

    return Result(_aaRange(cast(void*)aa));
}

auto byValue(T : V[K], K, V)(T* aa) pure nothrow @nogc
{
    return (*aa).byValue();
}

auto byKeyValue(T : V[K], K, V)(T aa) pure nothrow @nogc
{
    import core.internal.traits : substInout;

    static struct Result
    {
        AARange r;

    pure nothrow @nogc:
        @property bool empty() { return _aaRangeEmpty(r); }
        @property auto front() @trusted
        {
            static struct Pair
            {
                // We save the pointers here so that the Pair we return
                // won't mutate when Result.popFront is called afterwards.
                private void* keyp;
                private void* valp;

                @property ref key() inout { return *cast(substInout!K*)keyp; }
                @property ref value() inout { return *cast(substInout!V*)valp; }
            }
            return Pair(_aaRangeFrontKey(r),
                        _aaRangeFrontValue(r));
        }
        void popFront() { _aaRangePopFront(r); }
        @property Result save() { return this; }
    }

    return Result(_aaRange(cast(void*)aa));
}

auto byKeyValue(T : V[K], K, V)(T* aa) pure nothrow @nogc
{
    return (*aa).byKeyValue();
}

Key[] keys(T : Value[Key], Value, Key)(T aa) @property
{
    auto a = cast(void[])_aaKeys(cast(inout(void)*)aa, Key.sizeof, typeid(Key[]));
    auto res = *cast(Key[]*)&a;
    _doPostblit(res);
    return res;
}

Key[] keys(T : Value[Key], Value, Key)(T *aa) @property
{
    return (*aa).keys;
}

Value[] values(T : Value[Key], Value, Key)(T aa) @property
{
    auto a = cast(void[])_aaValues(cast(inout(void)*)aa, Key.sizeof, Value.sizeof, typeid(Value[]));
    auto res = *cast(Value[]*)&a;
    _doPostblit(res);
    return res;
}

Value[] values(T : Value[Key], Value, Key)(T *aa) @property
{
    return (*aa).values;
}

unittest
{
    static struct T
    {
        static size_t count;
        this(this) { ++count; }
    }
    T[int] aa;
    T t;
    aa[0] = t;
    aa[1] = t;
    assert(T.count == 2);
    auto vals = aa.values;
    assert(vals.length == 2);
    assert(T.count == 4);

    T.count = 0;
    int[T] aa2;
    aa2[t] = 0;
    assert(T.count == 1);
    aa2[t] = 1;
    assert(T.count == 1);
    auto keys = aa2.keys;
    assert(keys.length == 1);
    assert(T.count == 2);
}

inout(V) get(K, V)(inout(V[K]) aa, K key, lazy inout(V) defaultValue)
{
    auto p = key in aa;
    return p ? *p : defaultValue;
}

inout(V) get(K, V)(inout(V[K])* aa, K key, lazy inout(V) defaultValue)
{
    return (*aa).get(key, defaultValue);
}

pure nothrow unittest
{
    int[int] a;
    foreach (i; a.byKey)
    {
        assert(false);
    }
    foreach (i; a.byValue)
    {
        assert(false);
    }
}

pure /*nothrow @@@BUG5555@@@*/ unittest
{
    auto a = [ 1:"one", 2:"two", 3:"three" ];
    auto b = a.dup;
    assert(b == [ 1:"one", 2:"two", 3:"three" ]);

    int[] c;
    foreach (k; a.byKey)
    {
        c ~= k;
    }

    assert(c.length == 3);
    assert(c[0] == 1 || c[1] == 1 || c[2] == 1);
    assert(c[0] == 2 || c[1] == 2 || c[2] == 2);
    assert(c[0] == 3 || c[1] == 3 || c[2] == 3);
}

pure nothrow unittest
{
    // test for bug 5925
    const a = [4:0];
    const b = [4:0];
    assert(a == b);
}

pure nothrow unittest
{
    // test for bug 9052
    static struct Json {
        Json[string] aa;
        void opAssign(Json) {}
        size_t length() const { return aa.length; }
        // This length() instantiates AssociativeArray!(string, const(Json)) to call AA.length(), and
        // inside ref Slot opAssign(Slot p); (which is automatically generated by compiler in Slot),
        // this.value = p.value would actually fail, because both side types of the assignment
        // are const(Json).
    }
}

pure nothrow unittest
{
    // test for bug 8583: ensure Slot and aaA are on the same page wrt value alignment
    string[byte]    aa0 = [0: "zero"];
    string[uint[3]] aa1 = [[1,2,3]: "onetwothree"];
    ushort[uint[3]] aa2 = [[9,8,7]: 987];
    ushort[uint[4]] aa3 = [[1,2,3,4]: 1234];
    string[uint[5]] aa4 = [[1,2,3,4,5]: "onetwothreefourfive"];

    assert(aa0.byValue.front == "zero");
    assert(aa1.byValue.front == "onetwothree");
    assert(aa2.byValue.front == 987);
    assert(aa3.byValue.front == 1234);
    assert(aa4.byValue.front == "onetwothreefourfive");
}

pure nothrow unittest
{
    // test for bug 10720
    static struct NC
    {
        @disable this(this) { }
    }

    NC[string] aa;
    static assert(!is(aa.nonExistingField));
}

pure nothrow unittest
{
    // bug 5842
    string[string] test = null;
    test["test1"] = "test1";
    test.remove("test1");
    test.rehash;
    test["test3"] = "test3"; // causes divide by zero if rehash broke the AA
}

pure nothrow unittest
{
    string[] keys = ["a", "b", "c", "d", "e", "f"];

    // Test forward range capabilities of byKey
    {
        int[string] aa;
        foreach (key; keys)
            aa[key] = 0;

        auto keyRange = aa.byKey();
        auto savedKeyRange = keyRange.save;

        // Consume key range once
        size_t keyCount = 0;
        while (!keyRange.empty)
        {
            aa[keyRange.front]++;
            keyCount++;
            keyRange.popFront();
        }

        foreach (key; keys)
        {
            assert(aa[key] == 1);
        }
        assert(keyCount == keys.length);

        // Verify it's possible to iterate the range the second time
        keyCount = 0;
        while (!savedKeyRange.empty)
        {
            aa[savedKeyRange.front]++;
            keyCount++;
            savedKeyRange.popFront();
        }

        foreach (key; keys)
        {
            assert(aa[key] == 2);
        }
        assert(keyCount == keys.length);
    }

    // Test forward range capabilities of byValue
    {
        size_t[string] aa;
        foreach (i; 0 .. keys.length)
        {
            aa[keys[i]] = i;
        }

        auto valRange = aa.byValue();
        auto savedValRange = valRange.save;

        // Consume value range once
        int[] hasSeen;
        hasSeen.length = keys.length;
        while (!valRange.empty)
        {
            assert(hasSeen[valRange.front] == 0);
            hasSeen[valRange.front]++;
            valRange.popFront();
        }

        foreach (sawValue; hasSeen) { assert(sawValue == 1); }

        // Verify it's possible to iterate the range the second time
        hasSeen = null;
        hasSeen.length = keys.length;
        while (!savedValRange.empty)
        {
            assert(!hasSeen[savedValRange.front]);
            hasSeen[savedValRange.front] = true;
            savedValRange.popFront();
        }

        foreach (sawValue; hasSeen) { assert(sawValue); }
    }
}

pure nothrow unittest
{
    // expanded test for 5842: increase AA size past the point where the AA
    // stops using binit, in order to test another code path in rehash.
    int[int] aa;
    foreach (int i; 0 .. 32)
        aa[i] = i;
    foreach (int i; 0 .. 32)
        aa.remove(i);
    aa.rehash;
    aa[1] = 1;
}

pure nothrow unittest
{
    // bug 13078
    shared string[][string] map;
    map.rehash;
}

pure nothrow unittest
{
    // bug 11761: test forward range functionality
    auto aa = ["a": 1];

    void testFwdRange(R, T)(R fwdRange, T testValue)
    {
        assert(!fwdRange.empty);
        assert(fwdRange.front == testValue);
        static assert(is(typeof(fwdRange.save) == typeof(fwdRange)));

        auto saved = fwdRange.save;
        fwdRange.popFront();
        assert(fwdRange.empty);

        assert(!saved.empty);
        assert(saved.front == testValue);
        saved.popFront();
        assert(saved.empty);
    }

    testFwdRange(aa.byKey, "a");
    testFwdRange(aa.byValue, 1);
    //testFwdRange(aa.byPair, tuple("a", 1));
}

unittest
{
    // Issue 9119
    int[string] aa;
    assert(aa.byKeyValue.empty);

    aa["a"] = 1;
    aa["b"] = 2;
    aa["c"] = 3;

    auto pairs = aa.byKeyValue;

    auto savedPairs = pairs.save;
    size_t count = 0;
    while (!pairs.empty)
    {
        assert(pairs.front.key in aa);
        assert(pairs.front.value == aa[pairs.front.key]);
        count++;
        pairs.popFront();
    }
    assert(count == aa.length);

    // Verify that saved range can iterate over the AA again
    count = 0;
    while (!savedPairs.empty)
    {
        assert(savedPairs.front.key in aa);
        assert(savedPairs.front.value == aa[savedPairs.front.key]);
        count++;
        savedPairs.popFront();
    }
    assert(count == aa.length);
}

unittest
{
    // Verify iteration with const.
    auto aa = [1:2, 3:4];
    foreach (const t; aa.byKeyValue)
    {
        auto k = t.key;
        auto v = t.value;
    }
}

unittest
{
    // test for bug 14626
    static struct S
    {
        string[string] aa;
        inout(string) key() inout { return aa.byKey().front; }
        inout(string) val() inout { return aa.byValue().front; }
        auto keyval() inout { return aa.byKeyValue().front; }
    }

    S s = S(["a":"b"]);
    assert(s.key() == "a");
    assert(s.val() == "b");
    assert(s.keyval().key == "a");
    assert(s.keyval().value == "b");

    void testInoutKeyVal(inout(string) key)
    {
        inout(string)[typeof(key)] aa;

        foreach (i; aa.byKey()) {}
        foreach (i; aa.byValue()) {}
        foreach (i; aa.byKeyValue()) {}
    }

    const int[int] caa;
    static assert(is(typeof(caa.byValue().front) == const int));
}

private void _destructRecurse(S)(ref S s)
    if (is(S == struct))
{
    static if (__traits(hasMember, S, "__xdtor") &&
               // Bugzilla 14746: Check that it's the exact member of S.
               __traits(isSame, S, __traits(parent, s.__xdtor)))
        s.__xdtor();
}

private void _destructRecurse(E, size_t n)(ref E[n] arr)
{
    import core.internal.traits : hasElaborateDestructor;

    static if (hasElaborateDestructor!E)
    {
        foreach_reverse (ref elem; arr)
            _destructRecurse(elem);
    }
}

// Public and explicitly undocumented
void _postblitRecurse(S)(ref S s)
    if (is(S == struct))
{
    static if (__traits(hasMember, S, "__xpostblit") &&
               // Bugzilla 14746: Check that it's the exact member of S.
               __traits(isSame, S, __traits(parent, s.__xpostblit)))
        s.__xpostblit();
}

// Ditto
void _postblitRecurse(E, size_t n)(ref E[n] arr)
{
    import core.internal.traits : hasElaborateCopyConstructor;

    static if (hasElaborateCopyConstructor!E)
    {
        size_t i;
        scope(failure)
        {
            for (; i != 0; --i)
            {
                _destructRecurse(arr[i - 1]); // What to do if this throws?
            }
        }

        for (i = 0; i < arr.length; ++i)
            _postblitRecurse(arr[i]);
    }
}

// Test destruction/postblit order
@safe nothrow pure unittest
{
    string[] order;

    struct InnerTop
    {
        ~this() @safe nothrow pure
        {
            order ~= "destroy inner top";
        }

        this(this) @safe nothrow pure
        {
            order ~= "copy inner top";
        }
    }

    struct InnerMiddle {}

    version(none) // @@@BUG@@@ 14242
    struct InnerElement
    {
        static char counter = '1';

        ~this() @safe nothrow pure
        {
            order ~= "destroy inner element #" ~ counter++;
        }

        this(this) @safe nothrow pure
        {
            order ~= "copy inner element #" ~ counter++;
        }
    }

    struct InnerBottom
    {
        ~this() @safe nothrow pure
        {
            order ~= "destroy inner bottom";
        }

        this(this) @safe nothrow pure
        {
            order ~= "copy inner bottom";
        }
    }

    struct S
    {
        char[] s;
        InnerTop top;
        InnerMiddle middle;
        version(none) InnerElement[3] array; // @@@BUG@@@ 14242
        int a;
        InnerBottom bottom;
        ~this() @safe nothrow pure { order ~= "destroy outer"; }
        this(this) @safe nothrow pure { order ~= "copy outer"; }
    }

    string[] destructRecurseOrder;
    {
        S s;
        _destructRecurse(s);
        destructRecurseOrder = order;
        order = null;
    }

    assert(order.length);
    assert(destructRecurseOrder == order);
    order = null;

    S s;
    _postblitRecurse(s);
    assert(order.length);
    auto postblitRecurseOrder = order;
    order = null;
    S s2 = s;
    assert(order.length);
    assert(postblitRecurseOrder == order);
}

// Test static struct
nothrow @safe @nogc unittest
{
    static int i = 0;
    static struct S { ~this() nothrow @safe @nogc { i = 42; } }
    S s;
    _destructRecurse(s);
    assert(i == 42);
}

unittest
{
    // Bugzilla 14746
    static struct HasDtor
    {
        ~this() { assert(0); }
    }
    static struct Owner
    {
        HasDtor* ptr;
        alias ptr this;
    }

    Owner o;
    assert(o.ptr is null);
    destroy(o);     // must not reach in HasDtor.__dtor()
}

unittest
{
    // Bugzilla 14746
    static struct HasPostblit
    {
        this(this) { assert(0); }
    }
    static struct Owner
    {
        HasPostblit* ptr;
        alias ptr this;
    }

    Owner o;
    assert(o.ptr is null);
    _postblitRecurse(o);     // must not reach in HasPostblit.__postblit()
}

// Test handling of fixed-length arrays
// Separate from first test because of @@@BUG@@@ 14242
unittest
{
    string[] order;

    struct S
    {
        char id;

        this(this)
        {
            order ~= "copy #" ~ id;
        }

        ~this()
        {
            order ~= "destroy #" ~ id;
        }
    }

    string[] destructRecurseOrder;
    {
        S[3] arr = [S('1'), S('2'), S('3')];
        _destructRecurse(arr);
        destructRecurseOrder = order;
        order = null;
    }
    assert(order.length);
    assert(destructRecurseOrder == order);
    order = null;

    S[3] arr = [S('1'), S('2'), S('3')];
    _postblitRecurse(arr);
    assert(order.length);
    auto postblitRecurseOrder = order;
    order = null;

    auto arrCopy = arr;
    assert(order.length);
    assert(postblitRecurseOrder == order);
}

// Test handling of failed postblit
// Not nothrow or @safe because of @@@BUG@@@ 14242
/+ nothrow @safe +/ unittest
{
    static class FailedPostblitException : Exception { this() nothrow @safe { super(null); } }
    static string[] order;
    static struct Inner
    {
        char id;

        @safe:
        this(this)
        {
            order ~= "copy inner #" ~ id;
            if(id == '2')
                throw new FailedPostblitException();
        }

        ~this() nothrow
        {
            order ~= "destroy inner #" ~ id;
        }
    }

    static struct Outer
    {
        Inner inner1, inner2, inner3;

        nothrow @safe:
        this(char first, char second, char third)
        {
            inner1 = Inner(first);
            inner2 = Inner(second);
            inner3 = Inner(third);
        }

        this(this)
        {
            order ~= "copy outer";
        }

        ~this()
        {
            order ~= "destroy outer";
        }
    }

    auto outer = Outer('1', '2', '3');

    try _postblitRecurse(outer);
    catch(FailedPostblitException) {}
    catch(Exception) assert(false);

    auto postblitRecurseOrder = order;
    order = null;

    try auto copy = outer;
    catch(FailedPostblitException) {}
    catch(Exception) assert(false);

    assert(postblitRecurseOrder == order);
    order = null;

    Outer[3] arr = [Outer('1', '1', '1'), Outer('1', '2', '3'), Outer('3', '3', '3')];

    try _postblitRecurse(arr);
    catch(FailedPostblitException) {}
    catch(Exception) assert(false);

    postblitRecurseOrder = order;
    order = null;

    try auto arrCopy = arr;
    catch(FailedPostblitException) {}
    catch(Exception) assert(false);

    assert(postblitRecurseOrder == order);
}

/++
    Destroys the given object and puts it in an invalid state. It's used to
    destroy an object so that any cleanup which its destructor or finalizer
    does is done and so that it no longer references any other objects. It does
    $(I not) initiate a GC cycle or free any GC memory.
  +/
void destroy(T)(T obj) if (is(T == class))
{
    rt_finalize(cast(void*)obj);
}

void destroy(T)(T obj) if (is(T == interface))
{
    destroy(cast(Object)obj);
}

version(unittest) unittest
{
   interface I { }
   {
       class A: I { string s = "A"; this() {} }
       auto a = new A, b = new A;
       a.s = b.s = "asd";
       destroy(a);
       assert(a.s == "A");

       I i = b;
       destroy(i);
       assert(b.s == "A");
   }
   {
       static bool destroyed = false;
       class B: I
       {
           string s = "B";
           this() {}
           ~this()
           {
               destroyed = true;
           }
       }
       auto a = new B, b = new B;
       a.s = b.s = "asd";
       destroy(a);
       assert(destroyed);
       assert(a.s == "B");

       destroyed = false;
       I i = b;
       destroy(i);
       assert(destroyed);
       assert(b.s == "B");
   }
   // this test is invalid now that the default ctor is not run after clearing
   version(none)
   {
       class C
       {
           string s;
           this()
           {
               s = "C";
           }
       }
       auto a = new C;
       a.s = "asd";
       destroy(a);
       assert(a.s == "C");
   }
}

void destroy(T)(ref T obj) if (is(T == struct))
{
    _destructRecurse(obj);
    () @trusted {
        auto buf = (cast(ubyte*) &obj)[0 .. T.sizeof];
        auto init = cast(ubyte[])typeid(T).init();
        if (init.ptr is null) // null ptr means initialize to 0s
            buf[] = 0;
        else
            buf[] = init[];
    } ();
}

version(unittest) nothrow @safe @nogc unittest
{
   {
       struct A { string s = "A";  }
       A a;
       a.s = "asd";
       destroy(a);
       assert(a.s == "A");
   }
   {
       static int destroyed = 0;
       struct C
       {
           string s = "C";
           ~this() nothrow @safe @nogc
           {
               destroyed ++;
           }
       }

       struct B
       {
           C c;
           string s = "B";
           ~this() nothrow @safe @nogc
           {
               destroyed ++;
           }
       }
       B a;
       a.s = "asd";
       a.c.s = "jkl";
       destroy(a);
       assert(destroyed == 2);
       assert(a.s == "B");
       assert(a.c.s == "C" );
   }
}

void destroy(T : U[n], U, size_t n)(ref T obj) if (!is(T == struct))
{
    obj[] = U.init;
}

version(unittest) unittest
{
    int[2] a;
    a[0] = 1;
    a[1] = 2;
    destroy(a);
    assert(a == [ 0, 0 ]);
}

unittest
{
    static struct vec2f {
        float[2] values;
        alias values this;
    }

    vec2f v;
    destroy!vec2f(v);
}


void destroy(T)(ref T obj)
    if (!is(T == struct) && !is(T == interface) && !is(T == class) && !_isStaticArray!T)
{
    obj = T.init;
}

template _isStaticArray(T : U[N], U, size_t N)
{
    enum bool _isStaticArray = true;
}

template _isStaticArray(T)
{
    enum bool _isStaticArray = false;
}

version(unittest) unittest
{
   {
       int a = 42;
       destroy(a);
       assert(a == 0);
   }
   {
       float a = 42;
       destroy(a);
       assert(isnan(a));
   }
}

version (unittest)
{
    bool isnan(float x)
    {
        return x != x;
    }
}

private
{
    extern (C) void _d_arrayshrinkfit(const TypeInfo ti, void[] arr) nothrow;
    extern (C) size_t _d_arraysetcapacity(const TypeInfo ti, size_t newcapacity, void *arrptr) pure nothrow;
}

/**
 * (Property) Get the current capacity of a slice. The capacity is the size
 * that the slice can grow to before the underlying array must be
 * reallocated or extended.
 *
 * If an append must reallocate a slice with no possibility of extension, then
 * 0 is returned. This happens when the slice references a static array, or
 * if another slice references elements past the end of the current slice.
 *
 * Note: The capacity of a slice may be impacted by operations on other slices.
 */
@property size_t capacity(T)(T[] arr) pure nothrow
{
    return _d_arraysetcapacity(typeid(T[]), 0, cast(void *)&arr);
}
///
unittest
{
    //Static array slice: no capacity
    int[4] sarray = [1, 2, 3, 4];
    int[]  slice  = sarray[];
    assert(sarray.capacity == 0);
    //Appending to slice will reallocate to a new array
    slice ~= 5;
    assert(slice.capacity >= 5);

    //Dynamic array slices
    int[] a = [1, 2, 3, 4];
    int[] b = a[1 .. $];
    int[] c = a[1 .. $ - 1];
    debug(SENTINEL) {} else // non-zero capacity very much depends on the array and GC implementation
    {
        assert(a.capacity != 0);
        assert(a.capacity == b.capacity + 1); //both a and b share the same tail
    }
    assert(c.capacity == 0);              //an append to c must relocate c.
}

/**
 * Reserves capacity for a slice. The capacity is the size
 * that the slice can grow to before the underlying array must be
 * reallocated or extended.
 *
 * The return value is the new capacity of the array (which may be larger than
 * the requested capacity).
 */
size_t reserve(T)(ref T[] arr, size_t newcapacity) pure nothrow @trusted
{
    return _d_arraysetcapacity(typeid(T[]), newcapacity, cast(void *)&arr);
}
///
unittest
{
    //Static array slice: no capacity. Reserve relocates.
    int[4] sarray = [1, 2, 3, 4];
    int[]  slice  = sarray[];
    auto u = slice.reserve(8);
    assert(u >= 8);
    assert(sarray.ptr !is slice.ptr);
    assert(slice.capacity == u);

    //Dynamic array slices
    int[] a = [1, 2, 3, 4];
    a.reserve(8); //prepare a for appending 4 more items
    auto p = a.ptr;
    u = a.capacity;
    a ~= [5, 6, 7, 8];
    assert(p == a.ptr);      //a should not have been reallocated
    assert(u == a.capacity); //a should not have been extended
}

// Issue 6646: should be possible to use array.reserve from SafeD.
@safe unittest
{
    int[] a;
    a.reserve(10);
}

/**
 * Assume that it is safe to append to this array. Appends made to this array
 * after calling this function may append in place, even if the array was a
 * slice of a larger array to begin with.
 *
 * Use this only when it is certain there are no elements in use beyond the
 * array in the memory block.  If there are, those elements will be
 * overwritten by appending to this array.
 *
 * Calling this function, and then using references to data located after the
 * given array results in undefined behavior.
 *
 * Returns:
 *   The input is returned.
 */
auto ref inout(T[]) assumeSafeAppend(T)(auto ref inout(T[]) arr) nothrow
{
    _d_arrayshrinkfit(typeid(T[]), *(cast(void[]*)&arr));
    return arr;
}
///
unittest
{
    int[] a = [1, 2, 3, 4];

    // Without assumeSafeAppend. Appending relocates.
    int[] b = a [0 .. 3];
    b ~= 5;
    assert(a.ptr != b.ptr);

    debug(SENTINEL) {} else
    {
        // With assumeSafeAppend. Appending overwrites.
        int[] c = a [0 .. 3];
        c.assumeSafeAppend() ~= 5;
        assert(a.ptr == c.ptr);
    }
}

unittest
{
    int[] arr;
    auto newcap = arr.reserve(2000);
    assert(newcap >= 2000);
    assert(newcap == arr.capacity);
    auto ptr = arr.ptr;
    foreach(i; 0..2000)
        arr ~= i;
    assert(ptr == arr.ptr);
    arr = arr[0..1];
    arr.assumeSafeAppend();
    arr ~= 5;
    assert(ptr == arr.ptr);
}

unittest
{
    int[] arr = [1, 2, 3];
    void foo(ref int[] i)
    {
        i ~= 5;
    }
    arr = arr[0 .. 2];
    foo(assumeSafeAppend(arr)); //pass by ref
    assert(arr[]==[1, 2, 5]);
    arr = arr[0 .. 1].assumeSafeAppend(); //pass by value
}

//@@@10574@@@
unittest
{
    int[] a;
    immutable(int[]) b;
    auto a2 = &assumeSafeAppend(a);
    auto b2 = &assumeSafeAppend(b);
    auto a3 = assumeSafeAppend(a[]);
    auto b3 = assumeSafeAppend(b[]);
    assert(is(typeof(*a2) == int[]));
    assert(is(typeof(*b2) == immutable(int[])));
    assert(is(typeof(a3) == int[]));
    assert(is(typeof(b3) == immutable(int[])));
}

version (none)
{
    // enforce() copied from Phobos std.contracts for destroy(), left out until
    // we decide whether to use it.


    T _enforce(T, string file = __FILE__, int line = __LINE__)
        (T value, lazy const(char)[] msg = null)
    {
        if (!value) bailOut(file, line, msg);
        return value;
    }

    T _enforce(T, string file = __FILE__, int line = __LINE__)
        (T value, scope void delegate() dg)
    {
        if (!value) dg();
        return value;
    }

    T _enforce(T)(T value, lazy Exception ex)
    {
        if (!value) throw ex();
        return value;
    }

    private void _bailOut(string file, int line, in char[] msg)
    {
        char[21] buf;
        throw new Exception(cast(string)(file ~ "(" ~ ulongToString(buf[], line) ~ "): " ~ (msg ? msg : "Enforcement failed")));
    }
}


/***************************************
 * Helper function used to see if two containers of different
 * types have the same contents in the same sequence.
 */

bool _ArrayEq(T1, T2)(T1[] a1, T2[] a2)
{
    if (a1.length != a2.length)
        return false;
    foreach(i, a; a1)
    {
        if (a != a2[i])
            return false;
    }
    return true;
}

/**
Calculates the hash value of $(D arg) with $(D seed) initial value.
Result may be non-equals with $(D typeid(T).getHash(&arg))
The $(D seed) value may be used for hash chaining:
----
struct Test
{
    int a;
    string b;
    MyObject c;

    size_t toHash() const @safe pure nothrow
    {
        size_t hash = a.hashOf();
        hash = b.hashOf(hash);
        size_t h1 = c.myMegaHash();
        hash = h1.hashOf(hash); //Mix two hash values
        return hash;
    }
}
----
*/
size_t hashOf(T)(auto ref T arg, size_t seed = 0)
{
    import core.internal.hash;
    return core.internal.hash.hashOf(arg, seed);
}

bool _xopEquals(in void*, in void*)
{
    throw new Error("TypeInfo.equals is not implemented");
}

bool _xopCmp(in void*, in void*)
{
    throw new Error("TypeInfo.compare is not implemented");
}

void __ctfeWrite(T...)(auto ref T) {}
void __ctfeWriteln(T...)(auto ref T values) { __ctfeWrite(values, "\n"); }

/******************************************
 * Create RTInfo for type T
 */

template RTInfo(T)
{
    enum RTInfo = null;
}


// Helper functions

private inout(TypeInfo) getElement(inout TypeInfo value) @trusted pure nothrow
{
    TypeInfo element = cast() value;
    for(;;)
    {
        if(auto qualified = cast(TypeInfo_Const) element)
            element = qualified.base;
        else if(auto redefined = cast(TypeInfo_Typedef) element) // typedef & enum
            element = redefined.base;
        else if(auto staticArray = cast(TypeInfo_StaticArray) element)
            element = staticArray.value;
        else if(auto vector = cast(TypeInfo_Vector) element)
            element = vector.base;
        else
            break;
    }
    return cast(inout) element;
}

private size_t getArrayHash(in TypeInfo element, in void* ptr, in size_t count) @trusted nothrow
{
    if(!count)
        return 0;

    const size_t elementSize = element.tsize;
    if(!elementSize)
        return 0;

    static bool hasCustomToHash(in TypeInfo value) @trusted pure nothrow
    {
        const element = getElement(value);

        if(const struct_ = cast(const TypeInfo_Struct) element)
            return !!struct_.xtoHash;

        return cast(const TypeInfo_Array) element
            || cast(const TypeInfo_AssociativeArray) element
            || cast(const ClassInfo) element
            || cast(const TypeInfo_Interface) element;
    }

    import core.internal.traits : externDFunc;
    alias hashOf = externDFunc!("rt.util.hash.hashOf",
                                size_t function(const(void)*, size_t, size_t) @trusted pure nothrow);
    if(!hasCustomToHash(element))
        return hashOf(ptr, elementSize * count, 0);

    size_t hash = 0;
    foreach(size_t i; 0 .. count)
        hash += element.getHash(ptr + i * elementSize);
    return hash;
}


// @@@BUG5835@@@ tests:

unittest
{
    class C
    {
        int i;
        this(in int i) { this.i = i; }
        override hash_t toHash() { return 0; }
    }
    C[] a1 = [new C(11)], a2 = [new C(12)];
    assert(typeid(C[]).getHash(&a1) == typeid(C[]).getHash(&a2)); // fails
}

unittest
{
    struct S
    {
        int i;
        hash_t toHash() const @safe nothrow { return 0; }
    }
    S[] a1 = [S(11)], a2 = [S(12)];
    assert(typeid(S[]).getHash(&a1) == typeid(S[]).getHash(&a2)); // fails
}

@safe unittest
{
    struct S
    {
        int i;
    const @safe nothrow:
        hash_t toHash() { return 0; }
        bool opEquals(const S) { return true; }
        int opCmp(const S) { return 0; }
    }

    int[S[]] aa = [[S(11)] : 13];
    assert(aa[[S(12)]] == 13); // fails
}

/// Provide the .dup array property.
@property auto dup(T)(T[] a)
    if (!is(const(T) : T))
{
    import core.internal.traits : Unconst;
    static assert(is(T : Unconst!T), "Cannot implicitly convert type "~T.stringof~
                  " to "~Unconst!T.stringof~" in dup.");

    // wrap unsafe _dup in @trusted to preserve @safe postblit
    static if (__traits(compiles, (T b) @safe { T a = b; }))
        return _trustedDup!(T, Unconst!T)(a);
    else
        return _dup!(T, Unconst!T)(a);
}

/// ditto
// const overload to support implicit conversion to immutable (unique result, see DIP29)
@property T[] dup(T)(const(T)[] a)
    if (is(const(T) : T))
{
    // wrap unsafe _dup in @trusted to preserve @safe postblit
    static if (__traits(compiles, (T b) @safe { T a = b; }))
        return _trustedDup!(const(T), T)(a);
    else
        return _dup!(const(T), T)(a);
}

/// ditto
@property T[] dup(T:void)(const(T)[] a) @trusted
{
    if (__ctfe) assert(0, "Cannot dup a void[] array at compile time.");
    return cast(T[])_rawDup(a);
}

/// Provide the .idup array property.
@property immutable(T)[] idup(T)(T[] a)
{
    static assert(is(T : immutable(T)), "Cannot implicitly convert type "~T.stringof~
                  " to immutable in idup.");

    // wrap unsafe _dup in @trusted to preserve @safe postblit
    static if (__traits(compiles, (T b) @safe { T a = b; }))
        return _trustedDup!(T, immutable(T))(a);
    else
        return _dup!(T, immutable(T))(a);
}

/// ditto
@property immutable(T)[] idup(T:void)(const(T)[] a)
{
    return a.dup;
}

private U[] _trustedDup(T, U)(T[] a) @trusted
{
    return _dup!(T, U)(a);
}

private U[] _dup(T, U)(T[] a) // pure nothrow depends on postblit
{
    if (__ctfe)
    {
        U[] res;
        foreach (ref e; a)
            res ~= e;
        return res;
    }

    a = _rawDup(a);
    auto res = *cast(typeof(return)*)&a;
    _doPostblit(res);
    return res;
}

private extern (C) void[] _d_newarrayU(const TypeInfo ti, size_t length) pure nothrow;

private inout(T)[] _rawDup(T)(inout(T)[] a)
{
    import core.stdc.string : memcpy;

    void[] arr = _d_newarrayU(typeid(T[]), a.length);
    memcpy(arr.ptr, cast(void*)a.ptr, T.sizeof * a.length);
    return *cast(inout(T)[]*)&arr;
}

private template _PostBlitType(T)
{
    // assume that ref T and void* are equivalent in abi level.
    static if (is(T == struct))
        alias _PostBlitType = typeof(function (ref T t){ T a = t; });
    else
        alias _PostBlitType = typeof(delegate (ref T t){ T a = t; });
}

// Returns null, or a delegate to call postblit of T
private auto _getPostblit(T)() @trusted pure nothrow @nogc
{
    // infer static postblit type, run postblit if any
    static if (is(T == struct))
    {
        import core.internal.traits : Unqual;
        // use typeid(Unqual!T) here to skip TypeInfo_Const/Shared/...
        return cast(_PostBlitType!T)typeid(Unqual!T).xpostblit;
    }
    else if ((&typeid(T).postblit).funcptr !is &TypeInfo.postblit)
    {
        return cast(_PostBlitType!T)&typeid(T).postblit;
    }
    else
        return null;
}

private void _doPostblit(T)(T[] arr)
{
    // infer static postblit type, run postblit if any
    if (auto postblit = _getPostblit!T())
    {
        foreach (ref elem; arr)
            postblit(elem);
    }
}

unittest
{
    static struct S1 { int* p; }
    static struct S2 { @disable this(); }
    static struct S3 { @disable this(this); }

    int dg1() pure nothrow @safe
    {
        {
           char[] m;
           string i;
           m = m.dup;
           i = i.idup;
           m = i.dup;
           i = m.idup;
        }
        {
           S1[] m;
           immutable(S1)[] i;
           m = m.dup;
           i = i.idup;
           static assert(!is(typeof(m.idup)));
           static assert(!is(typeof(i.dup)));
        }
        {
            S3[] m;
            immutable(S3)[] i;
            static assert(!is(typeof(m.dup)));
            static assert(!is(typeof(i.idup)));
        }
        {
            shared(S1)[] m;
            m = m.dup;
            static assert(!is(typeof(m.idup)));
        }
        {
            int[] a = (inout(int)) { inout(const(int))[] a; return a.dup; }(0);
        }
        return 1;
    }

    int dg2() pure nothrow @safe
    {
        {
           S2[] m = [S2.init, S2.init];
           immutable(S2)[] i = [S2.init, S2.init];
           m = m.dup;
           m = i.dup;
           i = m.idup;
           i = i.idup;
        }
        return 2;
    }

    enum a = dg1();
    enum b = dg2();
    assert(dg1() == a);
    assert(dg2() == b);
}

unittest
{
    static struct Sunpure { this(this) @safe nothrow {} }
    static struct Sthrow { this(this) @safe pure {} }
    static struct Sunsafe { this(this) @system pure nothrow {} }

    static assert( __traits(compiles, ()         { [].dup!Sunpure; }));
    static assert(!__traits(compiles, () pure    { [].dup!Sunpure; }));
    static assert( __traits(compiles, ()         { [].dup!Sthrow; }));
    static assert(!__traits(compiles, () nothrow { [].dup!Sthrow; }));
    static assert( __traits(compiles, ()         { [].dup!Sunsafe; }));
    static assert(!__traits(compiles, () @safe   { [].dup!Sunsafe; }));

    static assert( __traits(compiles, ()         { [].idup!Sunpure; }));
    static assert(!__traits(compiles, () pure    { [].idup!Sunpure; }));
    static assert( __traits(compiles, ()         { [].idup!Sthrow; }));
    static assert(!__traits(compiles, () nothrow { [].idup!Sthrow; }));
    static assert( __traits(compiles, ()         { [].idup!Sunsafe; }));
    static assert(!__traits(compiles, () @safe   { [].idup!Sunsafe; }));
}

unittest
{
    static int*[] pureFoo() pure { return null; }
    { char[] s; immutable x = s.dup; }
    { immutable x = (cast(int*[])null).dup; }
    { immutable x = pureFoo(); }
    { immutable x = pureFoo().dup; }
}

unittest
{
    auto a = [1, 2, 3];
    auto b = a.dup;
    debug(SENTINEL) {} else
        assert(b.capacity >= 3);
}

unittest
{
    // Bugzilla 12580
    void[] m = [0];
    shared(void)[] s = [cast(shared)1];
    immutable(void)[] i = [cast(immutable)2];

    s = s.dup;
    static assert(is(typeof(s.dup) == shared(void)[]));

    m = i.dup;
    i = m.dup;
    i = i.idup;
    i = m.idup;
    i = s.idup;
    i = s.dup;
    static assert(!__traits(compiles, m = s.dup));
}

unittest
{
    // Bugzilla 13809
    static struct S
    {
        this(this) {}
        ~this() {}
    }

    S[] arr;
    auto a = arr.dup;
}
