[cfe-dev] Inconsistent IA-64 name mangling between gcc and Clang for template functions with a local class template parameter

[Richard Smith]

This has been brought up on cxx-abi-dev:

http://sourcerytools.com/pipermail/cxx-abi-dev/2012-June/002429.html

On Mon, Jun 4, 2012 at 2:01 PM, Tom Honermann <thonermann at coverity.com> wrote:
> I recently happened along code for which gcc and Clang generate
> different IA-64 external names.  A test case follows.  The name in
> question is for the template specialization of 'foo' parametrized with
> local class 'Item' of 'X<int>::test<char>(char&) const'
>
> $ cat test.cpp
> template<typename T>
> const T *foo(const T &t) {
>       return &t;
> }
>
> template<typename T>
> struct X {
>       template<typename U>
>       void test(U &) const {
>           struct Item {} x;
>           foo(x);
>       }
> };
>
> int main() {
>       X<int> x;
>       char c;
>       x.test(c);
> }
>
> $ g++ --version
> g++ (GCC) 4.5.2
> Copyright (C) 2010 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions.  There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
>
> $ g++ -std=c++0x -c test.cpp
> $ nm test.o | grep foo
> 00000000 W _Z3fooIZNK1XIiE4testIcEEvRT_E4ItemEPKT_RS7_
>
> $ clang --version
> clang version 3.1 (branches/release_31)
> Target: x86_64-unknown-linux-gnu
> Thread model: posix
>
> $ clang -std=c++0x -c test.cpp
> $ nm test.o | grep foo
> 0000000000000020 t _Z3fooIZNK1XIiE4testIcEEvRT_E4ItemEPKS3_RS6_
>
> For ease of comparison, that's:
> _Z3fooIZNK1XIiE4testIcEEvRT_E4ItemEPKT_RS7_  (gcc)
> _Z3fooIZNK1XIiE4testIcEEvRT_E4ItemEPKS3_RS6_ (clang)
>
> It seems that Clang is implementing a substitution candidate that gcc is
> not.  My reading of the IA-64 ABI specification
> (http://sourcery.mentor.com/public/cxx-abi/abi.html) leaves me unclear
> as to what the correct mangling should be.
>
> Tom.
>
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