[MacPorts] #57578: __has_feature(cxx_exceptions) returns true but fails to compile std::uncaught_exceptions()

[MacPorts]

#57578: __has_feature(cxx_exceptions) returns true but fails to compile
std::uncaught_exceptions()
-------------------------+-------------------------------------------------
  Reporter:  noloader    |      Owner:  (none)
      Type:  defect      |     Status:  new
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:
Resolution:              |   Keywords:  C++17 cxx_exceptions
      Port:              |  std::uncaught_exceptions()
  clang++-mp-6.0         |
-------------------------+-------------------------------------------------
Description changed by noloader:

Old description:

> I'm testing C++17 on OS X 10.8.5 and 10.9.5 using Macports Clang compiler
> versions 5.0 and 6.0. Attempting to compile the following program:
>
>   $ cat test.cxx
>   #if __EXCEPTIONS && __has_feature(cxx_exceptions)
>   # include <exception>
>   # define CXX17_EXCEPTIONS 1
>   #endif
>
>   void Foo()
>   {
>   #if defined(CXX17_EXCEPTIONS)
>       if (std::uncaught_exceptions() == 0)
>   #endif
>       {
>           int x = 0;
>       }
>   }
>
> Results in:
>
> $ /opt/local/bin/clang++-mp-5.0 -std=gnu++17 test.cxx -c
> test.cxx:9:14: error: 'uncaught_exceptions' is unavailable: introduced in
> macOS 10.12
>     if (std::uncaught_exceptions() == 0)
>              ^
> /opt/local/libexec/llvm-5.0/include/c++/v1/exception:130:63: note:
>       'uncaught_exceptions' has been explicitly marked unavailable here
> _LIBCPP_FUNC_VIS _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS int
> uncaught_e...
>                                                               ^
> -std=c++17 produces the same error.
>
> According to the LLVM 3.6 release notes
> (https://releases.llvm.org/3.6.0/tools/clang/docs/ReleaseNotes.html#the-
> exceptions-macro), I believe I am using the correct feature test:
>
>     To reliably test if C++ exceptions are enabled,
>     use __EXCEPTIONS && __has_feature(cxx_exceptions),
>     else things won’t work in all versions of Clang in
>     Objective-C++ files.
>
> ==========
>
> Upstream issue report at https://bugs.llvm.org/show_bug.cgi?id=39631
>
> ==========
>
> $ /opt/local/bin/clang++-mp-6.0 --version
> clang version 6.0.1 (tags/RELEASE_601/final)
> Target: x86_64-apple-darwin13.4.0
> Thread model: posix
> InstalledDir: /opt/local/libexec/llvm-6.0/bin
>
> $ /opt/local/bin/clang++-mp-5.0 --version
> clang version 5.0.2 (tags/RELEASE_502/final)
> Target: x86_64-apple-darwin13.4.0
> Thread model: posix
> InstalledDir: /opt/local/libexec/llvm-5.0/bin
>
> $ sw_vers
> ProductName:    Mac OS X
> ProductVersion: 10.9.5
> BuildVersion:   13F1911

New description:

 I'm testing C++17 on OS X 10.8.5 and 10.9.5 using Macports Clang compiler
 versions 5.0 and 6.0. Attempting to compile the following program:

 {{{
 $ cat test.cxx
 #if __EXCEPTIONS && __has_feature(cxx_exceptions)
 # include <exception>
 # define CXX17_EXCEPTIONS 1
 #endif

 void Foo()
 {
 #if defined(CXX17_EXCEPTIONS)
     if (std::uncaught_exceptions() == 0)
 #endif
     {
         int x = 0;
     }
 }
 }}}

 Results in:

 {{{
 $ /opt/local/bin/clang++-mp-5.0 -std=gnu++17 test.cxx -c
 test.cxx:9:14: error: 'uncaught_exceptions' is unavailable: introduced in
 macOS 10.12
     if (std::uncaught_exceptions() == 0)
              ^
 /opt/local/libexec/llvm-5.0/include/c++/v1/exception:130:63: note:
       'uncaught_exceptions' has been explicitly marked unavailable here
 _LIBCPP_FUNC_VIS _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS int
 uncaught_e...
 }}}
                                                            ^
 -std=c++17 produces the same error.

 According to the LLVM 3.6 release notes
 (https://releases.llvm.org/3.6.0/tools/clang/docs/ReleaseNotes.html#the-
 exceptions-macro), I believe I am using the correct feature test:

     To reliably test if C++ exceptions are enabled,
     use __EXCEPTIONS && __has_feature(cxx_exceptions),
     else things won’t work in all versions of Clang in
     Objective-C++ files.

 ==========

 Upstream issue report at https://bugs.llvm.org/show_bug.cgi?id=39631

 ==========

 $ /opt/local/bin/clang++-mp-6.0 --version
 clang version 6.0.1 (tags/RELEASE_601/final)
 Target: x86_64-apple-darwin13.4.0
 Thread model: posix
 InstalledDir: /opt/local/libexec/llvm-6.0/bin

 $ /opt/local/bin/clang++-mp-5.0 --version
 clang version 5.0.2 (tags/RELEASE_502/final)
 Target: x86_64-apple-darwin13.4.0
 Thread model: posix
 InstalledDir: /opt/local/libexec/llvm-5.0/bin

 $ sw_vers
 ProductName:    Mac OS X
 ProductVersion: 10.9.5
 BuildVersion:   13F1911

--

-- 
Ticket URL: <https://trac.macports.org/ticket/57578#comment:1>
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