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# dmd.clone

Define the implicit opEquals, opAssign, post blit, copy constructor and destructor for structs.
Authors:
Walter Bright
License:
Boost License 1.0

Source clone.d

Documentation https://dlang.org/phobos/dmd_clone.html

Coverage https://codecov.io/gh/dlang/dmd/src/master/src/dmd/clone.d

pure StorageClass `mergeFuncAttrs`(StorageClass `s1`, const FuncDeclaration `f`);
  Merge function attributes pure, nothrow, @safe, @nogc, and @disable from f into s1.
  Parameters:

  StorageClass `s1` | storage class to merge into
  FuncDeclaration `f` | function

  Returns:
  merged storage class
FuncDeclaration `hasIdentityOpAssign`(AggregateDeclaration `ad`, Scope* `sc`);
  Check given aggregate actually has an identity opAssign or not.
  Parameters:

  AggregateDeclaration `ad` | struct or class
  Scope* `sc` | current scope

  Returns:
  if found, returns FuncDeclaration of opAssign, otherwise null
FuncDeclaration `buildOpAssign`(StructDeclaration `sd`, Scope* `sc`);
  Build opAssign for a struct.
  The generated opAssign function has the following signature:

      ref S opAssign(S s)    // S is the name of the `struct`

  The opAssign function will be built for a struct S if the following constraints are met:
  1. S does not have an identity opAssign defined.
  2. S has at least one of the following members: a postblit (user-defined or generated for fields that have a defined postblit), a destructor (user-defined or generated for fields that have a defined destructor) or at least one field that has a defined opAssign.
  3. S does not have any non-mutable fields.
  If S has a disabled destructor or at least one field that has a disabled opAssign, S.opAssign is going to be generated, but marked with @disable
  If S defines a destructor, the generated code for opAssign is:

      S __swap = void;
      __swap = this;   // bit copy
      this = s;        // bit copy
      __swap.dtor();

  Otherwise, if S defines a postblit, the generated code for opAssign is:

      this = s;

  Note that the parameter to the generated opAssign is passed by value, which means that the postblit is going to be called (if it is defined) in both of the above situations before entering the body of opAssign. The assignments in the above generated function bodies are blit expressions, so they can be regarded as memcpys (opAssign is not called as this will result in an infinite recursion; the postblit is not called because it has already been called when the parameter was passed by value).
  If S does not have a postblit or a destructor, but contains at least one field that defines an opAssign function (which is not disabled), then the body will make member-wise assignments:

      this.field1 = s.field1;
      this.field2 = s.field2;
      ...;

  In this situation, the assignemnts are actual assign expressions (opAssign is used if defined).

  References https://dlang.org/spec/struct.html#assign-overload

  Parameters:

  StructDeclaration `sd` | struct to generate opAssign for
  Scope* `sc` | context

  Returns:
  generated opAssign function
bool `needOpEquals`(StructDeclaration `sd`);
  We need an opEquals for the struct if any fields has an opEquals. Generate one if a user-specified one does not exist.
FuncDeclaration `buildOpEquals`(StructDeclaration `sd`, Scope* `sc`);
  Build opEquals for struct. const bool opEquals(const S s) { ... }
  By fixing https://issues.dlang.org/show_bug.cgi?id=3789 opEquals is changed to be never implicitly generated. Now, struct objects comparison s1 == s2 is translated to: s1.tupleof == s2.tupleof to calculate structural equality. See EqualExp.op_overload.
FuncDeclaration `buildXopEquals`(StructDeclaration `sd`, Scope* `sc`);
  Build __xopEquals for TypeInfo_Struct static bool __xopEquals(ref const S p, ref const S q) { return p == q; }
  This is called by TypeInfo.equals(p1, p2). If the struct does not support const objects comparison, it will throw "not implemented" Error in runtime.
FuncDeclaration `buildXopCmp`(StructDeclaration `sd`, Scope* `sc`);
  Build __xopCmp for TypeInfo_Struct static bool __xopCmp(ref const S p, ref const S q) { return p.opCmp(q); }
  This is called by TypeInfo.compare(p1, p2). If the struct does not support const objects comparison, it will throw "not implemented" Error in runtime.
FuncDeclaration `buildXtoHash`(StructDeclaration `sd`, Scope* `sc`);
  Build _xtoHash for non-bitwise hashing static hash_t xtoHash(ref const S p) nothrow @trusted;
DtorDeclaration `buildDtor`(AggregateDeclaration `ad`, Scope* `sc`);
  Create inclusive destructor for struct/class by aggregating all the destructors in dtors[] with the destructors for all the members.
  Parameters:

  AggregateDeclaration `ad` | struct or class to build destructor for
  Scope* `sc` | context

  Returns:
  generated function, null if none needed

  Note Close similarity with StructDeclaration::buildPostBlit(), and the ordering changes (runs backward instead of forwards).

DtorDeclaration `buildExternDDtor`(AggregateDeclaration `ad`, Scope* `sc`);
  build a shim function around the compound dtor that translates a C++ destructor to a destructor with extern(D) calling convention
  Parameters:

  AggregateDeclaration `ad` | the aggregate that contains the destructor to wrap
  Scope* `sc` | the scope in which to analyze the new function

  Returns:
  the shim destructor, semantically analyzed and added to the class as a member
FuncDeclaration `buildInv`(AggregateDeclaration `ad`, Scope* `sc`);
  Create inclusive invariant for struct/class by aggregating all the invariants in invs[]. void __invariant() const [pure nothrow @trusted] { invs[0](), invs[1](), ...; }

Copyright © 1999-2020 by the D Language Foundation | Page generated by Ddoc on Tue Jul 7 12:25:58 2020