C89 had a questionable feature where the compiler would implicitly
declare a function that the user called but was never previously
declared. The resulting function would be globally declared as
extern int func(); -- a function without a prototype which accepts zero
or more arguments.
C99 removed support for this questionable feature due to severe
security concerns. However, there was no deprecation period; C89 had
the feature, C99 didn't. So Clang (and GCC) both supported the
functionality as an extension in C99 and later modes.
C2x no longer supports that function signature as it now requires all
functions to have a prototype, and given the known security issues with
the feature, continuing to support it as an extension is not tenable.
This patch changes the diagnostic behavior for the
-Wimplicit-function-declaration warning group depending on the language
mode in effect. We continue to warn by default in C89 mode (due to the
feature being dangerous to use). However, because this feature will not
be supported in C2x mode, we've diagnosed it as being invalid for so
long, the security concerns with the feature, and the trivial
workaround for users (declare the function), we now default the
extension warning to an error in C99-C17 mode. This still gives users
an easy workaround if they are extensively using the extension in those
modes (they can disable the warning or use -Wno-error to downgrade the
error), but the new diagnostic makes it more clear that this feature is
not supported and should be avoided. In C2x mode, we no longer allow an
implicit function to be defined and treat the situation the same as any
other lookup failure.
Differential Revision: https://reviews.llvm.org/D122983
This adds -no-opaque-pointers to clang tests whose output will
change when opaque pointers are enabled by default. This is
intended to be part of the migration approach described in
https://discourse.llvm.org/t/enabling-opaque-pointers-by-default/61322/9.
The patch has been produced by replacing %clang_cc1 with
%clang_cc1 -no-opaque-pointers for tests that fail with opaque
pointers enabled. Worth noting that this doesn't cover all tests,
there's a remaining ~40 tests not using %clang_cc1 that will need
a followup change.
Differential Revision: https://reviews.llvm.org/D123115
The Microsoft-extension _MoveToCoprocessor and _MoveToCoprocessor2
builtins take the register value to be moved as the first argument,
but the corresponding mcr and mcr2 LLVM intrinsics expect that value
to be the third argument. Handle this as a special case, while still
leaving those intrinsics as generic MSBuiltins. I considered the
alternative of handling these in EmitARMBuiltinExpr, but that does
not work well for the follow-up change that I'm going to make to improve
the error handling for PR22560 -- we need the GetBuiltinType() checks
for ICEArguments, and the ARM version of that code is only used for
Neon intrinsics where the last argument is special and not
checked in the normal way.
llvm-svn: 240462
This adds support for simple MSVC compatibility mode intrinsics. These
intrinsics are simple in that they are either directly passed through to the
annotated MSBuiltin intrinsic or they mirror existing GCC builtins.
llvm-svn: 212378
Nikita Popov