Issue 3659 & others - Relax opEquals signature

[9rnsr]

http://d.puremagic.com/issues/show_bug.cgi?id=3659

requires: druntime git://github.com/9rnsr/druntime.git relax_opEquals_sig

Points:

• Remove opEquals signature restriction.

  We can define any signatures of opEquals, even if it is template funciton.

• Make stub for TypeInfo_Struct.xopEquals

  (Needs druntime fix, see Supplemental changes of dmd/pull/373 druntime#70)

  TypeInfo.equals gets two lvalue through in void*.
  So we should make stub for calling user opEquals.

  xopEquals = bool function(in void* p, in void* q) {
      return ( *cast(const S*)p ).opEquals( *cast(const S*)q );
  };
  

  // If user opEquals is qualified const, and gets ref const S, and returns bool,
  // we can set its function pointer to xopEquals directly.
  // But it is not yet implemented.

  If this stub couldn't compile, stub code is replaced with follows:

  xopEquals = bool function(in void* p, in void* q) {
      throw Error("TypeInfo.equals is not implemented")
  };
  

  TypeInfo.equals should not break both objects constness, so we cannot call
  the opEquals that breaks objects constness. Instead throws Error at runtime.

• If no user opEquals (and need opEquals definition), compiler builds following opEquals automatically.

  const bool opEquals(const S rhs) { ... }

  This signature can receive rvalue of S, and const copy of lvalue.

[yebblies]

The requires line says phobos but points to druntime.git !

Also you probably mean 'stub' not 'stab'.

[9rnsr]

Thanks for your pointing out, yebblies!

[yebblies]

This now seems to be causing a linker failure.

[9rnsr]

@yebblies
This patch includes copy-constructor signature changing (it is only used for internal code generation), so it is necessary to rebuild phobos.

[yebblies]

If this works for you then it's probably a problem with having another version of phobos on the linker path. I'll have a look, it wouldn't be the first time.

[yebblies]

Yep, using the wrong dmd.conf. Should be correct the run after next.

[braddr]

Removal of this import broke this test on 64 bit platforms