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

[Dimitry Andric via Phabricator via cfe-commits]

dim abandoned this revision.
dim added a comment.

Ok, back to Mozilla we go.


https://reviews.llvm.org/D28981



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

[Eric Fiselier via Phabricator via cfe-commits]

EricWF resigned from this revision.
EricWF added a comment.

I think we've agreed that this change shouldn't proceed. Resigning as reviewer.


https://reviews.llvm.org/D28981



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

[Jonathan Wakely via Phabricator via cfe-commits]

jwakely added a comment.

The __throw_xxx functions are not part of the public libstdc++ API and whatever 
Firefox is trying to do with them is not supported by libstdc++ and is 
undefined behaviour. Make it stop.


https://reviews.llvm.org/D28981



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

[Dimitry Andric via Phabricator via cfe-commits]

dim added a comment.

In https://reviews.llvm.org/D28981#653908, @mclow.lists wrote:

> > In https://reviews.llvm.org/rL279744, __throw_XXX() functions were 
> > introduced, partially for compatibility with software compiled against 
> > libstdc++.
>
> You're working from a false premise.  These functions were not added for 
> compatibility with libstdc++, but rather to encapsulate the mechanism for 
> throwing an exception - to localize the changes needed to support 
> `-fno-exceptions`


Ok, I was mistaken about the premise, but by accident (or by their 
self-evidentness) the names are still shared with the GNU names.  It would be 
nice to have some way of making them semi-compatible.  Alternatively, we could 
rename them, but that would be more churn, I guess.


https://reviews.llvm.org/D28981



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

[Dimitry Andric via Phabricator via cfe-commits]

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
  __throw_bad_alloc(void)
  ^

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_bad_alloc(void)
  __throw_bad_cast(void)
  __throw_bad_exception(void)
  __throw_bad_function_call(void)
  __throw_bad_typeid(void)
  __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_system_error(int)
  __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.


https://reviews.llvm.org/D28981

Files:
  include/__config
  include/__locale
  include/functional
  include/new
  include/stdexcept
  include/system_error
  include/typeinfo

Index: include/typeinfo
===
--- include/typeinfo
+++ include/typeinfo
@@ -190,7 +190,7 @@
 }  // std
 
 _LIBCPP_BEGIN_NAMESPACE_STD
-_LIBCPP_NORETURN inline _LIBCPP_ALWAYS_INLINE
+_LIBCPP_NORETURN_GNU inline _LIBCPP_ALWAYS_INLINE
 void __throw_bad_cast()
 {
 #ifndef _LIBCPP_NO_EXCEPTIONS
Index: include/system_error
===
--- include/system_error
+++ include/system_error
@@ -664,7 +664,7 @@
 static string __init(const error_code&, string);
 };
 
-_LIBCPP_NORETURN _LIBCPP_FUNC_VIS
+_LIBCPP_NORETURN_GNU _LIBCPP_FUNC_VIS
 void __throw_system_error(int ev, const char* what_arg);
 
 _LIBCPP_END_NAMESPACE_STD
Index: include/stdexcept
===
--- include/stdexcept
+++ include/stdexcept
@@ -183,9 +183,9 @@
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 // in the dylib
-_LIBCPP_NORETURN _LIBCPP_FUNC_VIS void __throw_runtime_error(const char*);
+_LIBCPP_NORETURN_GNU _LIBCPP_FUNC_VIS void __throw_runtime_error(const char*);
 
-_LIBCPP_NORETURN inline _LIBCPP_ALWAYS_INLINE
+_LIBCPP_NORETURN_GNU inline _LIBCPP_ALWAYS_INLINE
 void __throw_logic_error(const char*__msg)
 {
 #ifndef _LIBCPP_NO_EXCEPTIONS
@@ -196,7 +196,7 @@
 #endif
 }
 
-_LIBCPP_NORETURN inline _LIBCPP_ALWAYS_INLINE
+_LIBCPP_NORETURN_GNU inline _LIBCPP_ALWAYS_INLINE
 void __throw_domain_error(const char*__msg)
 {
 #ifndef _LIBCPP_NO_EXCEPTIONS
@@ -207,7 +207,7 @@
 #endif
 }
 
-_LIBCPP_NORETURN inline _LIBCPP_ALWAYS_INLINE
+_LIBCPP_NORETURN_GNU inline _LIBCPP_ALWAYS_INLINE
 void __throw_invalid_argument(const char*__msg)
 {
 #ifndef _LIBCPP_NO_EXCEPTIONS
@@ -218,7 +218,7 @@
 #endif
 }
 
-_LIBCPP_NORETURN inline _LIBCPP_ALWAYS_INLINE
+_LIBCPP_NORETURN_GNU inline _LIBCPP_ALWAYS_INLINE
 void __throw_length_error(const char*__msg)
 {
 #ifndef _LIBCPP_NO_EXCEPTIONS
@@ -229,7 +229,7 @@
 #endif
 }
 
-_LIBCPP_NORETURN inline _LIBCPP_ALWAYS_INLINE
+_LIBCPP_NORETURN_GNU inline _LIBCPP_ALWAYS_INLINE
 void __throw_out_of_range(const char*__msg)
 {
 #ifndef _LIBCPP_NO_EXCEPTIONS
@@ -240,7 +240,7 @@
 #endif
 }
 
-_LIBCPP_NORETURN inline _LIBCPP_ALWAYS_INLINE
+_LIBCPP_NORETURN_GNU inline _LIBCPP_ALWAYS_INLINE
 void __throw_range_error(const char*__msg)
 {
 #ifndef _LIBCPP_NO_EXCEPTIONS
@@ -251,7 +251,7 @@
 #endif
 }
 
-_LIBCPP_NORETURN inline _LIBCPP_ALWAYS_INLINE
+_LIBCPP_NORETURN_GNU inline _LIBCPP_ALWAYS_INLINE
 void __throw_overflow_error(const char*__msg)
 {
 #ifndef _LIBCPP_NO_EXCEPTIONS
@@ -262,7 +262,7 @@
 #endif
 }
 
-_LIBCPP_NORETURN inline _LIBCPP_ALWAYS_INLINE
+_LIBCPP_NORETURN_GNU inline _LIBCPP_ALWAYS_INLINE
 void __throw_underflow_error(const char*__msg)
 {
 #ifndef