Currently, we emit warnings in some cases where nonnull function
parameters are compared against null. This patch extends this support
to warn when comparing the result of `returns_nonnull` functions
against null.
More specifically, we will now warn cases like:
int *foo() __attribute__((returns_nonnull));
int main() {
if (foo() == NULL) {} // warning: will always evaluate to false
}
Differential Revision: http://reviews.llvm.org/D15324
llvm-svn: 255058
nonnull attribute when comparison is always true/false.
Original patch by Steven Wu. I have added extra code to prevent issuing of
warning when the nonnull parameter is modified prior to the comparison.
This addition prevents false positives in the most obvious cases.
There may still be false positive warnings in some cases (as one of my tests
indicates), but benefit far outweighs such cases. rdar://18712242
llvm-svn: 222264
parameters with nonnull attribute when comparison is always
true/false. Patch causes false positive when parameter is
modified in the function.
llvm-svn: 221163
nonnull attribute when comparison is always
true/false. Patch by Steven Wu with few fixes and minor
refactoring and adding tests by me. rdar://18712242
llvm-svn: 220496
the no-arguments case. Don't expand this to an __attribute__((nonnull(A, B,
C))) attribute, since that does the wrong thing for function templates and
varargs functions.
In passing, fix a grammar error in the diagnostic, a crash if
__attribute__((nonnull(N))) is applied to a varargs function,
a bug where the same null argument could be diagnosed multiple
times if there were multiple nonnull attributes referring to it,
and a bug where nonnull attributes would not be accumulated correctly
across redeclarations.
llvm-svn: 216520
Thanks to r199467, __attribute__((nonnull)) (without arguments) can apply
directly to parameters, instead of being applied to the whole function.
However, the old form of nonnull (with an argument index) could also apply
to the arguments of function and block pointers, and both of these can be
passed as parameters.
Now, if 'nonnull' with an argument is found on a parameter, /and/ the
parameter is a function or block pointer, it is handled the old way.
PR18795
llvm-svn: 201162
This involved making CheckReturnStackAddr into a static function, which
is now called by a top-level return value checking routine called
CheckReturnValExpr.
llvm-svn: 199790
This attribute is supported by GCC. More generally it should
probably be a type attribute, but this behavior matches 'nonnull'.
This patch does not include warning logic for checking if a null
value is returned from a function annotated with this attribute.
That will come in subsequent patches.
llvm-svn: 199626
This allows the following syntax:
void baz(__attribute__((nonnull)) const char *str);
instead of:
void baz(const char *str) __attribute__((nonnull(1)));
This also extends to Objective-C methods.
The checking logic in Sema is not as clean as I would like. Effectively
now we need to check both the FunctionDecl/ObjCMethodDecl and the parameters,
so the point of truth is spread in two places, but the logic isn't that
cumbersome.
Implements <rdar://problem/14691443>.
llvm-svn: 199467
Since this warning was generalized, it was also given a sensible warning group flag and the corresponding test was updated to reflect this.
llvm-svn: 198053
Objective-C pointers to using ObjCObjectPointerType.
Now the checking for 'attribute ((nonnull))' in Sema doesn't emit an error when
trying to apply that attribute to a parameter that is an Objective-C pointer
(this is a regression).
To prevent this regression from occuring in the future, the 'nonnull.c' test was
moved to test/SemaObjC and renamed 'nonnull.m'. I also enhanced the tests to
show that function calls involved a NULL Objective-C pointer constant does not
trigger a warning. This is consistent with GCC, but should likely be fixed.
llvm-svn: 75856
- warn about nonnull being applied to functions with no pointer arguments
- continue processing argument list in the attribute when we encounter a non-pointer parameter being marked as nonnull
- when no argument list is specified, only mark pointers as nonnull. This fixes PR 2732 and radar 6188814.
llvm-svn: 55610
Aaron Ballman