[PATCH] D28981: Use GNU-style attributes for several __throw_XXX() functions

Dimitry Andric via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Sat Jan 21 08:02:58 PST 2017

dim created this revision.

In https://reviews.llvm.org/rL279744, `__throw_XXX()` functions were introduced, partially for compatibility with software compiled against libstdc++.  `_LIBCPP_NORETURN` is used on all of them, and when C++11 attributes are available, this gets defined as `[[noreturn]]`, instead of the GNU-style `__attribute__((noreturn))` style.

However, this can cause trouble with some software, for example Mozilla Firefox, which attempts to redefine several of these `__throw_XXX()` functions, and but uses the `__attribute__((noreturn))` style exclusively.  This then leads to errors like:

  /usr/include/c++/v1/new:130:1: error: function declared '[[noreturn]]' after its first declaration
  _LIBCPP_NORETURN _LIBCPP_FUNC_VIS void __throw_bad_alloc();  // not in C++ spec
  /usr/include/c++/v1/__config:283:30: note: expanded from macro '_LIBCPP_NORETURN'
  #  define _LIBCPP_NORETURN [[noreturn]]
  ../../dist/include/mozilla/throw_gcc.h:35:1: note: declaration missing '[[noreturn]]' attribute is here

See also https://bugs.freebsd.org/216186 and https://bugzilla.mozilla.org/1329520 .  In Firefox's case, the following list of functions is affected:

  __throw_domain_error(const char*)
  __throw_invalid_argument(const char*)
  __throw_ios_failure(const char*)
  __throw_length_error(const char*)
  __throw_logic_error(const char*)
  __throw_out_of_range(const char*)
  __throw_overflow_error(const char*)
  __throw_range_error(const char*)
  __throw_runtime_error(const char*)
  __throw_underflow_error(const char*)

To make it easier on third-party software, let's define a `LIBCPP_NORETURN_GNU` variant, which always uses the `__attribute__((noreturn))` style, and apply it specifically to the above list of functions.

This should also be merged to the 4.0 branch, when it has been committed.



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