Summary:
The current implementation of `hash_code()` for uniqued RTTI strings violates strict aliasing by dereferencing a type-punned pointer. Specifically it generates a `const char**` pointer from the address of the `__name` member before casting it to `const size_t*` and dereferencing it to get the hash. This is really just a complex and incorrect way of writing `reinterpret_cast<size_t>(__name)`.
This patch changes the conversion sequence so that it no longer contains UB.
Reviewers: howard.hinnant, mclow.lists
Subscribers: rjmccall, cfe-commits
Differential Revision: https://reviews.llvm.org/D24012
llvm-svn: 283408
This patch removes the `<cstdlib>` include from exception where it is no longer
needed. Unlike my previous attempt this patch also adds <cstdlib> where needed
in other headers like <new> and <typeinfo>.
This won't fix the Firefox build issues discussed on IRC but it is more correct
for libc++.
llvm-svn: 280754
Apparently I missed a number of additional include which need to be added.
Reverting so I can recommit as a single patch with all of the required includes.
llvm-svn: 280752
Summary:
Currently a number of GCC warnings are emitted when building libc++. This patch fixes or ignores all of them. The primary changes are:
* Work around strict aliasing issues in `typeinfo::hash_code()` by using __attribute__((may_alias)). However I think a non-aliasing `hash_code()` implementation is possible. Further investigation needed.
* Add `_LIBCPP_UNREACHABLE()` to switch in `strstream.cpp` to avoid -Wpotentially-uninitialized.
* Fix -Wunused-value warning in `__all` by adding a void cast.
* Ignore -Wattributes for now. There are a number of real attribute issues when using GCC but enabling the warning is too noisy.
* Ignore -Wliteral-suffix since it warns about the use of reserved identifiers. Note Only GCC 7.0 supports disabling this warning.
* Ignore -Wc++14-compat since it warns about the sized new/delete overloads.
Reviewers: EricWF
Differential Revision: https://reviews.llvm.org/D24003
llvm-svn: 280007
It's identical to name() these days. (At one point it avoided masking
of the RTTI uniqueness bit because ARM64 ignored it architecturally,
but no longer).
llvm-svn: 205518
ARM64 generates RTTI with hidden visibility, which means that typeinfo
must be compared char-by-char since it's not guaranteed to be uniqued
across the whole program.
llvm-svn: 205139