Post-commit feedback on https://reviews.llvm.org/D122895 pointed out
that the diagnostic wording for some code was using "declaration" in a
confusing way, such as:
int foo(); // warning: a function declaration without a prototype is deprecated in all versions of C and is not supported in C2x
int foo(int arg) { // warning: a function declaration without a prototype is deprecated in all versions of C and is not supported in C2x
return 5;
}
And that we had other minor issues with the diagnostics being somewhat
confusing.
This patch addresses the confusion by reworking the implementation to
be a bit more simple and a bit less chatty. Specifically, it changes
the warning and note diagnostics to be able to specify "declaration" or
"definition" as appropriate, and it changes the function merging logic
so that the function without a prototype is always what gets warned on,
and the function with a prototype is sometimes what gets noted.
Additionally, when diagnosing a K&R C definition that is preceded by a
function without a prototype, we don't note the prior declaration, we
warn on it because it will also be changing behavior in C2x.
Differential Revision: https://reviews.llvm.org/D125814
Functions without prototypes in C (also known as K&R C functions) were
introduced into C89 as a deprecated feature and C2x is now reclaiming
that syntax space with different semantics. However, Clang's
-Wstrict-prototypes diagnostic is off-by-default (even in pedantic
mode) and does not suffice to warn users about issues in their code.
This patch changes the behavior of -Wstrict-prototypes to only diagnose
declarations and definitions which are not going to change behavior in
C2x mode, and enables the diagnostic in -pedantic mode. The diagnostic
is now specifically about the fact that the feature is deprecated.
It also adds -Wdeprecated-non-prototype, which is grouped under
-Wstrict-prototypes and diagnoses declarations or definitions which
will change behavior in C2x mode. This diagnostic is enabled by default
because the risk is higher for the user to continue to use the
deprecated feature.
Differential Revision: https://reviews.llvm.org/D122895
...function type with a redeclaration having the same attribute. Fixing this
introduced a secondary problem where we were assuming that K&R functions
could not be attributed types when reporting old-style function definitions
that are not preceded by a prototype."
Also Revert "Hopefully fixes a compile error introduced by r294861."
This reverts commit r294862, r294861, as they bork the ARM builds and
haven't fix it back.
Also, please, short commit titles, long commit decsriptions...
llvm-svn: 294910
Moves the bool bail-out down a little in SemaChecking - so now
-Wnull-conversion and -Wliteral-conversion can fire when the target type is
bool.
Also improve the wording/details in the -Wliteral-conversion warning to match
the -Wconstant-conversion.
llvm-svn: 156826
rewriting the literal when the value is integral. It is not uncommon to
see code written as:
const int kBigNumber = 42e5;
Without any real awareness that this is no longer an ICE. The note helps
automate and ease the process of fixing code that violates the warning.
llvm-svn: 129243
specifically targets literals which are implicitly converted, a those
are more often unintended and trivial to fix. This can be especially
helpful for diagnosing what makes 'const int x = 1e6' not an ICE.
Original patch authored by Jim Meehan with contributions from other
Googlers and a few cleanups from myself.
llvm-svn: 125745
function definition, we should still use a prototype to type-check and
convert the function arguments, if such a prototype exists. Fixes
PR8314.
llvm-svn: 117305
- This is designed to make it obvious that %clang_cc1 is a "test variable"
which is substituted. It is '%clang_cc1' instead of '%clang -cc1' because it
can be useful to redefine what gets run as 'clang -cc1' (for example, to set
a default target).
llvm-svn: 91446
prototype of the same function, where the promoted parameter types in
the K&R definition are not compatible with the types in the
prototype. Fixes PR2821.
llvm-svn: 66301
only from a function definition (that does not have a prototype) are
only used to determine the compatible with other declarations of that
same function. In particular, when referencing the function we pretend
as if it does not have a prototype. Implement this behavior, which
fixes PR3626.
llvm-svn: 65460
Aaron Ballman