http://llvm.org/bugs/show_bug.cgi?id=18063
Bug ID: 18063
Summary: Support multiple instances of the nonnull function
attribute
Product: clang
Version: 3.3
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: -New Bugs
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
GCC supports specifying the nonnull attribute[1] multiple times for the same
function, and it collects the argument indices from all of them.
e.g. The following two code snippets are equivalent for GCC:
void my_func (void *p1, void *p2)
__attribute__((nonnull(1)))
__attribute__((nonnull(2)));
and
void my_func (void *p1, void *p2)
__attribute__((nonnull(1, 2)));
Currently, however, Clang ignores all except the final attribute, so for Clang,
the code:
void my_func (void *p1, void *p2)
__attribute__((nonnull(1)))
__attribute__((nonnull(2)));
is actually equivalent to:
void my_func (void *p1, void *p2)
__attribute__((nonnull(2)));
It would be nice if Clang followed the GCC behaviour here. Specifically, this
would be nice for GLib: we have a G_GNUC_NON_NULL(P) macro which expands to
__attribute__((nonnull(P))) if the attribute is supported. We can’t make the
macro variadic, as we still need to support old compilers (such as MS Visual
C), but we can allow the macro to be instantiated several times.
[1]:
http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#index-g_t_0040code_007bnonnull_007d-function-attribute-2825
[2]: https://bugzilla.gnome.org/show_bug.cgi?id=113075
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