[testsuite] Fix C++11 compilation failure for gdb.cp/m-static.exp

  Hi,

gcc-6.2.1-1.fc26.x86_64

g++ -std=c++03:
no warnings

g++:
In file included from /home/jkratoch/redhat/gdb-clean/gdb/testsuite/gdb.cp/m-static.cc:79:0:
/home/jkratoch/redhat/gdb-clean/gdb/testsuite/gdb.cp/m-static.h:9:34: error: ‘constexpr’ needed for in-class initialization of static data member ‘const float gnu_obj_4::somewhere’ of non-integral type [-fpermissive]
   static const float somewhere = 3.14159;
                                  ^~~~~~~

clang++:
In file included from /home/jkratoch/redhat/gdb-clean/gdb/testsuite/gdb.cp/m-static.cc:79:
/home/jkratoch/redhat/gdb-clean/gdb/testsuite/gdb.cp/m-static.h:9:22: warning: in-class initializer for static data member of type 'const float' is a GNU extension [-Wgnu-static-float-init]
  static const float somewhere = 3.14159;
                     ^           ~~~~~~~
1 warning generated.

clang++ -std=c++11:
In file included from /home/jkratoch/redhat/gdb-clean/gdb/testsuite/gdb.cp/m-static.cc:79:
/home/jkratoch/redhat/gdb-clean/gdb/testsuite/gdb.cp/m-static.h:9:22: error: in-class initializer for static data member of type 'const float' requires 'constexpr' specifier [-Wstatic-float-init]
  static const float somewhere = 3.14159;
                     ^           ~~~~~~~
/home/jkratoch/redhat/gdb-clean/gdb/testsuite/gdb.cp/m-static.h:9:3: note: add 'constexpr'
  static const float somewhere = 3.14159;
  ^
  constexpr
1 error generated.

OK for check-in?

After the fix out of the 4 combinations above only this one remains non-empty:

clang++:
In file included from /home/jkratoch/redhat/gdb-clean/gdb/testsuite/gdb.cp/m-static.cc:79:
/home/jkratoch/redhat/gdb-clean/gdb/testsuite/gdb.cp/m-static.h:9:22: warning: in-class initializer for static data member of type 'const float' is a GNU extension [-Wgnu-static-float-init]
  static const float somewhere = 3.14159;
                     ^           ~~~~~~~
1 warning generated.


Jan
gdb/testsuite/ChangeLog
2016-09-11  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.cp/m-static.h (gnu_obj_4::somewhere): Use constexpr for C++11.
  

On 09/11/2016 03:22 PM, Jan Kratochvil wrote:
> 
> After the fix out of the 4 combinations above only this one remains non-empty:
> 
> clang++:
> In file included from /home/jkratoch/redhat/gdb-clean/gdb/testsuite/gdb.cp/m-static.cc:79:
> /home/jkratoch/redhat/gdb-clean/gdb/testsuite/gdb.cp/m-static.h:9:22: warning: in-class initializer for static data member of type 'const float' is a GNU extension [-Wgnu-static-float-init]
>   static const float somewhere = 3.14159;
>                      ^           ~~~~~~~
> 1 warning generated.
> 

Did you try moving the initialization to the .cc file?  Like:

const float gnu_obj_4::somewhere = 3.14159;

Did you find a reason to not do that?

Thanks,
Pedro Alves