r333325 from D47225 added warning checks, and the test was written to be C++11 correct by using ATOMIC_VAR_INIT (note that the committee fixed that recently...). It seems like GCC can't handle ATOMIC_VAR_INIT well because it generates 'type 'std::atomic<int>' cannot be initialized with an initializer list' on bot libcxx-libcxxabi-x86_64-linux-ubuntu-cxx03. Drop the ATOMIC_VAR_INITs since they weren't required to test the diagnostics.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@333327 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The atomic non-member functions accept pointers to std::atomic / std::atomic_flag as well as to the non-atomic value. These are all dereferenced unconditionally when lowered, and therefore will fault if null. It's a tiny gotcha for new users, especially when they pass in NULL as expected value (instead of passing a pointer to a NULL value). We can therefore use the nonnull attribute to denote that:
- A warning should be generated if the argument is null
- It is undefined behavior if the argument is null (because a dereference will segfault)
This patch adds support for this attribute for clang and GCC, and sticks to the subset of the syntax both supports. In particular, work around this GCC oddity:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60625
The attributes are documented:
- https://gcc.gnu.org/onlinedocs/gcc-4.0.0/gcc/Function-Attributes.html
- https://clang.llvm.org/docs/AttributeReference.html#nullability-attributes
I'm authoring a companion clang patch for the __c11_* and __atomic_* builtins, which currently only warn on a subset of the pointer parameters.
In all cases the check needs to be explicit and not use the empty nonnull list, because some of the overloads are for atomic<T*> and the values themselves are allowed to be null.
<rdar://problem/18473124>
Reviewers: arphaman, EricWF
Subscribers: aheejin, christof, cfe-commits
Differential Revision: https://reviews.llvm.org/D47225
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@333325 91177308-0d34-0410-b5e6-96231b3b80d8
