forked from pool/nodejs-electron
36 lines
1.9 KiB
Diff
36 lines
1.9 KiB
Diff
|
Make DEFINE_GLOBAL C++17 compliant.
|
||
|
|
|
||
|
|
The pointer to an object is not interconvertible with the pointer to its underlying storage,
|
||
|
|
and GCC raises a Wstrict-aliasing warning about UB resulting from the dereference.
|
||
|
|
(This is really a pointer provenance issue, not a type aliasing issue, as the underlying
|
||
|
|
void*[] is never actually directly used)
|
||
|
|
Additionally, void* potentially has a too-small alignment for some types (eg. long double).
|
||
|
|
|
||
|
|
We fix the fist issue by memory laundering, and the second by switching to aligned_storage_t.
|
||
|
|
|
||
|
|
--- src/third_party/blink/renderer/platform/wtf/static_constructors.h.old 2022-10-20 19:00:30.237477900 +0200
|
||
|
|
+++ src/third_party/blink/renderer/platform/wtf/static_constructors.h 2022-10-29 21:48:44.336995700 +0200
|
||
|
|
@@ -21,8 +21,11 @@
|
||
|
|
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_STATIC_CONSTRUCTORS_H_
|
||
|
|
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_STATIC_CONSTRUCTORS_H_
|
||
|
|
|
||
|
|
+#include <new>
|
||
|
|
+#include <type_traits>
|
||
|
|
+
|
||
|
|
// We need to avoid having static constructors. This is accomplished by defining
|
||
|
|
-// a static array of the appropriate size and alignment, and defining a const
|
||
|
|
+// a buffer of the appropriate size and alignment, and defining a const
|
||
|
|
// reference that points to the buffer. During initialization, the object will
|
||
|
|
// be constructed with placement new into the buffer. This works with MSVC, GCC,
|
||
|
|
// and Clang without producing dynamic initialization code even at -O0. The only
|
||
|
|
@@ -33,7 +36,7 @@
|
||
|
|
// Use an array of pointers instead of an array of char in case there is some
|
||
|
|
// alignment issue.
|
||
|
|
#define DEFINE_GLOBAL(type, name) \
|
||
|
|
- void* name##Storage[(sizeof(type) + sizeof(void*) - 1) / sizeof(void*)]; \
|
||
|
|
- const type& name = *reinterpret_cast<type*>(&name##Storage)
|
||
|
|
+ std::aligned_storage_t<sizeof(type), alignof(type)> name##Storage; \
|
||
|
|
+ const type& name = *std::launder(reinterpret_cast<type*>(&name##Storage))
|
||
|
|
|
||
|
|
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_STATIC_CONSTRUCTORS_H_
|