r197184 - [-cxx-abi microsoft] Mangle reference temporaries

[Richard Smith]

Using the mangled name of the variable for its lifetime-extended
temporaries doesn't sound right to me. Given:

  int n;
  int &&r = +n;

Clang generates:

  @"\01?r@@3$$QEAHEA" = global i32* null, align 8
  @"\01?r@@3$$QEAHEA1" = private global i32 0, align 4

... where the latter is the lifetime-extended temporary, with a suspicious
mangling.


Given:

  int &&r = 0;

Clang asserts:

  Global variable initializer type does not match global variable type!
  i32** @"\01?r@@3$$QEAHEA"
  Broken module found, compilation aborted!


On Thu, Dec 12, 2013 at 3:12 PM, David Majnemer <david.majnemer at gmail.com>wrote:

> Author: majnemer
> Date: Thu Dec 12 17:12:01 2013
> New Revision: 197184
>
> URL: http://llvm.org/viewvc/llvm-project?rev=197184&view=rev
> Log:
> [-cxx-abi microsoft] Mangle reference temporaries
>
> They are mangled the same as normal references, nothing special is going
> on here.
>
> Modified:
>     cfe/trunk/lib/AST/MicrosoftMangle.cpp
>     cfe/trunk/test/CodeGenCXX/mangle-ms.cpp
>
> Modified: cfe/trunk/lib/AST/MicrosoftMangle.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/MicrosoftMangle.cpp?rev=197184&r1=197183&r2=197184&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/AST/MicrosoftMangle.cpp (original)
> +++ cfe/trunk/lib/AST/MicrosoftMangle.cpp Thu Dec 12 17:12:01 2013
> @@ -2040,10 +2040,9 @@ void MicrosoftMangleContextImpl::mangleC
>  }
>
>  void MicrosoftMangleContextImpl::mangleReferenceTemporary(const VarDecl
> *VD,
> -                                                          raw_ostream &) {
> -  unsigned DiagID = getDiags().getCustomDiagID(DiagnosticsEngine::Error,
> -    "cannot mangle this reference temporary yet");
> -  getDiags().Report(VD->getLocation(), DiagID);
> +                                                          raw_ostream
> &Out) {
> +  MicrosoftCXXNameMangler mangler(*this, Out);
> +  mangler.mangle(VD);
>  }
>
>  void MicrosoftMangleContextImpl::mangleStaticGuardVariable(const VarDecl
> *VD,
>
> Modified: cfe/trunk/test/CodeGenCXX/mangle-ms.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/mangle-ms.cpp?rev=197184&r1=197183&r2=197184&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/CodeGenCXX/mangle-ms.cpp (original)
> +++ cfe/trunk/test/CodeGenCXX/mangle-ms.cpp Thu Dec 12 17:12:01 2013
> @@ -445,3 +445,10 @@ decltype(a) fun(decltype(a) x, decltype(
>  // CHECK-DAG: ?fun at PR18022@@YA?AU<unnamed-type-a>@1 at U21@0 at Z
>
>  }
> +
> +// Binding to a bit-field that requires a temporary.
> +struct { int bitfield : 3; } object_with_bitfield = { 3 };
> +const int &reference_to_bitfield = object_with_bitfield.bitfield;
> +// CHECK-DAG: ?object_with_bitfield@
> @3U<unnamed-type-object_with_bitfield>@@A
> +// CHECK-DAG: ?reference_to_bitfield@@3ABHB
> +// CHECK-DAG: ??__Ereference_to_bitfield@@YAXXZ
>
>
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