[cfe-dev] Invalid mangled names emitted for local types declared in Apple Block expressions used in non-static data member initializers

[Tom Honermann via cfe-dev]

Clang appears to be generating ill-formed mangled names for local types 
declared in Apple Block expressions used as non-static data member 
initializers:

$ cat t.cpp
template<typename T> void tf(T) {}
struct S {
   void(^bp)() = ^{
     enum E {} e;
     tf(e);
   };
};
auto x = S{}.bp;

$ clang++ --version
clang version 4.0.0 (tags/RELEASE_400/final)
Target: x86_64-unknown-linux-gnu
Thread model: posix
...

$ clang++ -c -std=c++11 -fblocks t.cpp
$ nm t.o
...
0000000000000000 W _Z2tfIZ1S2bpMUb0_E1EEvT_
...

The mangled name generated for the function template specialization 
instantiated for the local enum type 'E' uses a <pointer-to-member-type> 
production [1] (as signified by 'M'), but only one of the two required 
dependent productions is present (<class type> via 'Ub0_', but not 
<member type>).

If someone can confirm that this is not intentional (it could be since 
Apple Blocks aren't governed by the Itanium ABI), I'll file a new BZ for 
this.

Additionally, for unnamed local types, discriminators are not added to 
disambiguate such types.  Bug 34511 [2] has been filed for that issue.

Tom.

[1]: 
http://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangle.pointer-to-member-type
[2]: https://bugs.llvm.org/show_bug.cgi?id=34511