I noticed that compiling on Windows with -fno-ms-compatibility had the
side effect of defining __GNUC__, along with __GNUG__, __GXX_RTTI__, and
a number of other macros for GCC compatibility. This is undesirable and
causes Chromium to do things like mix __attribute__ and __declspec,
which doesn't work. We should have a positive language option to enable
GCC compatibility features so that we can experiment with
-fno-ms-compatibility on Windows. This change adds -fgnuc-version= to be
that option.
My issue aside, users have, for a long time, reported that __GNUC__
doesn't match their expectations in one way or another. We have
encouraged users to migrate code away from this macro, but new code
continues to be written assuming a GCC-only environment. There's really
nothing we can do to stop that. By adding this flag, we can allow them
to choose their own adventure with __GNUC__.
This overlaps a bit with the "GNUMode" language option from -std=gnu*.
The gnu language mode tends to enable non-conforming behaviors that we'd
rather not enable by default, but the we want to set things like
__GXX_RTTI__ by default, so I've kept these separate.
Helps address PR42817
Reviewed By: hans, nickdesaulniers, MaskRay
Differential Revision: https://reviews.llvm.org/D68055
llvm-svn: 374449
We already prohibited this in most cases (in r130710), but had some bugs in our
enforcement of this rule. Specifically, this prevents the following
combinations:
* -x c -std=clN.M, which would previously effectively act as if -x cl were
used, despite the input being a C source file. (-x cl -std=cNN continues
to be disallowed.)
* -x c++ -std=cuda, which would previously select C++98 + CUDA, despite that
not being a C++ standard. (-x cuda -std=c++NN is still permitted, and
selects CUDA with the given C++ standard as its base language.
-x cuda -std=cuda is still supported with the meaning of CUDA + C++98.)
* -x renderscript -std=c++NN, which would previously form a hybrid "C++ with
RenderScript extensions" language. We could support such a thing, but
shouldn't do so by accident.
llvm-svn: 301497
Previously we were setting LangOptions::GNUInline (which controls whether we
use traditional GNU inline semantics) if the language did not have the C99
feature flag set. The trouble with this is that C++ family languages also
do not have that flag set, so we ended up setting this flag in C++ modes
(and working around it in a few places downstream by also checking CPlusPlus).
The fix is to check whether the C89 flag is set for the target language,
rather than whether the C99 flag is cleared. This also lets us remove most
CPlusPlus checks. We continue to test CPlusPlus when deciding whether to
pre-define the __GNUC_GNU_INLINE__ macro for consistency with GCC.
There is a change in semantics in two other places
where we weren't checking both CPlusPlus and GNUInline
(FunctionDecl::doesDeclarationForceExternallyVisibleDefinition and
FunctionDecl::isInlineDefinitionExternallyVisible), but this change seems to
put us back into line with GCC's semantics (test case: test/CodeGen/inline.c).
While at it, forbid -fgnu89-inline in C++ modes, as GCC doesn't support it,
it didn't have any effect before, and supporting it just makes things more
complicated.
Differential Revision: http://reviews.llvm.org/D9333
llvm-svn: 237299
Reid Kleckner