Clang has traditionally allowed C programs to implicitly convert
integers to pointers and pointers to integers, despite it not being
valid to do so except under special circumstances (like converting the
integer 0, which is the null pointer constant, to a pointer). In C89,
this would result in undefined behavior per 3.3.4, and in C99 this rule
was strengthened to be a constraint violation instead. Constraint
violations are most often handled as an error.
This patch changes the warning to default to an error in all C modes
(it is already an error in C++). This gives us better security posture
by calling out potential programmer mistakes in code but still allows
users who need this behavior to use -Wno-error=int-conversion to retain
the warning behavior, or -Wno-int-conversion to silence the diagnostic
entirely.
Differential Revision: https://reviews.llvm.org/D129881
This reverts commit d374b65f2d.
The changes lose AST fidelity (reported in #55778), but also may be
improperly dropping _Atomic qualifiers. I am rolling the changes back
until I've finished discussions in WG14 about the proper resolution to
DR423.
WG14 DR423 (https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2148.htm#dr_423),
resolved during the C11 time frame, changed the way qualifiers are
handled on function return types and in cast expressions after it was
noted that these types are now directly observable via generic
selection expressions. In C, the function declarator is adjusted to
ignore all qualifiers (including _Atomic qualifiers).
Clang already handles the cast expression case correctly (by performing
the lvalue conversion, which drops the qualifiers as well), but with
these changes it will now also handle function declarations
appropriately.
Fixes#39595
Differential Revision: https://reviews.llvm.org/D125919
C89 allowed a type specifier to be elided with the resulting type being
int, aka implicit int behavior. This feature was subsequently removed
in C99 without a deprecation period, so implementations continued to
support the feature. Now, as with implicit function declarations, is a
good time to reevaluate the need for this support.
This patch allows -Wimplicit-int to issue warnings in C89 mode (off by
default), defaults the warning to an error in C99 through C17, and
disables support for the feature entirely in C2x. It also removes a
warning about missing declaration specifiers that really was just an
implicit int warning in disguise and other minor related cleanups.
This patch adds -Wno-strict-prototypes to all of the test cases that
use functions without prototypes, but not as the primary concern of the
test. e.g., attributes testing whether they can/cannot be applied to a
function without a prototype, etc.
This is done in preparation for enabling -Wstrict-prototypes by
default.
WG14 has adopted N2480 (http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2480.pdf)
into C2x at the meetings last week, allowing parameter names of a function
definition to be elided. This patch relaxes the error so that C++ and C2x do not
diagnose this situation, and modes before C2x will allow it as an extension.
This also adds the same feature to ObjC blocks under the assumption that ObjC
wishes to follow the C standard in this regard.
The goal of this sugar node is to be able to look at an arbitrary
FunctionType and tell if any of the parameters were decayed from an
array or function type. Ultimately this is necessary to implement
Microsoft's C++ name mangling scheme, which mangles decayed arrays
differently from normal pointers.
Reviewers: rsmith
Differential Revision: http://llvm-reviews.chandlerc.com/D1014
llvm-svn: 184763
- 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
scheme to be more useful.
The new scheme introduces a set of categories that should be more
readable, and also reflects what we want to consider as an extension
more accurately. Specifically, it makes the "what is a keyword"
determination accurately reflect whether the keyword is a GNU or
Microsoft extension.
I also introduced separate flags for keyword aliases; this is useful
because the classification of the aliases is mostly unrelated to the
classification of the original keyword.
This patch treats anything that's in the implementation
namespace (prefixed with "__", or "_X" where "X" is any upper-case
letter) as a keyword without marking it as an extension. This is
consistent with the standards in that an implementation is allowed to define
arbitrary extensions in the implementation namespace without violating
the standard. This gets rid of all the nasty "extension used" warnings
for stuff like __attribute__ in -pedantic mode. We still warn for
extensions outside of the the implementation namespace, like typeof.
If someone wants to implement -Wextensions or something like that, we
could add additional information to the keyword table.
This also removes processing for the unused "Boolean" language option;
such an extension isn't supported on any other C implementation, so I
don't see any point to adding it.
The changes to test/CodeGen/inline.c are required because previously, we
weren't actually disabling the "inline" keyword in -std=c89 mode.
I'll remove Boolean and NoExtensions from LangOptions in a follow-up
commit.
llvm-svn: 70281
always return a non-null QualType + error bit. This fixes a bunch of
cases that didn't check for null result (and could thus crash) and eliminates
some crappy code scattered throughout sema.
This also improves the diagnostics in the recursive struct case to eliminate
a bogus second error. It also cleans up the case added to function.c by forming
a proper function type even though the declarator is erroneous, allowing the
parameter to be added to the function. Before:
t.c:2:1: error: unknown type name 'unknown_type'
unknown_type f(void*P)
^
t.c:4:3: error: use of undeclared identifier 'P'
P+1;
^
After:
t.c:2:1: error: unknown type name 'unknown_type'
unknown_type f(void*P)
^
llvm-svn: 70023
parameters in a functiondecl, even if the decl is invalid and has a confusing
Declarator. On the testcase, we now emit one beautiful diagnostic:
t.c:2:1: error: unknown type name 'unknown_type'
unknown_type f(void*)
^
GCC 4.0 produces:
t.c:2: error: syntax error before ‘f’
t.c: In function ‘f’:
t.c:2: error: parameter name omitted
and GCC 4.2:
t.c:2: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘f’
llvm-svn: 70016
typedef void foo(void);
We get a typedef for a functiontypeproto with no arguments, not
one with one argument and type void. This means the code being
removed in SemaDecl is dead.
llvm-svn: 70013
extern. Previously we would warn about it and ignore the attribute.
This is incorrect, it should be handled as a c89 "extern inline"
function. Many thanks to Matthieu Castet for pointing this out and
beating me over the head until I got it.
PR3988: extern inline function are not externally visible
llvm-svn: 69756
- When we are declaring a function in local scope, we can merge with
a visible declaration from an outer scope if that declaration
refers to an entity with linkage. This behavior now works in C++
and properly ignores entities without linkage.
- Diagnose the use of "static" on a function declaration in local
scope.
- Diagnose the declaration of a static function after a non-static
declaration of the same function.
- Propagate the storage specifier to a function declaration from a
prior declaration (PR3425)
- Don't name-mangle "main"
llvm-svn: 65360
special action, inside function prototype scope. This avoids confusion
when we try to inject these parameters into the scope of the function
body before the function itself has been added to the surrounding
scope. Fixes <rdar://problem/6097326>.
llvm-svn: 62849
Tightening up this routine forced tweaks to Sema::CheckSubtractionOperands() and Sema::CheckCompareOperands(). For example, they both need to operate on the unqualified pointee...
llvm-svn: 46522
Aaron Ballman