[base] fix builds with GCC 12 on certain Linux distributions

joyeecheung · V8 LUCI CQ · commit 35888fee7bba · 2024-07-23T09:18:44.000Z
With GCC 12 on certain Linux distributions (at least Debian 12, Alpine 3.18, Fedora 37, that ships GCC 12.2), std::is_trivially_copyable is broken and as a result, V8 fails to compile. This patch uses the same polyfill on MSVC to make it compile with GCC 12.2. See nodejs/node#45427 for more context. Refs: https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=aeba3e009b0abfccaf01797556445dbf891cc8dc Change-Id: Ie0ab1bb1ec105bacbd80b341adf7dbd8569f031f Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/5679182 Commit-Queue: Joyee Cheung <joyee@igalia.com> Reviewed-by: Nico Hartmann <nicohartmann@chromium.org> Cr-Commit-Position: refs/heads/main@{#95181}
diff --git a/src/base/macros.h b/src/base/macros.h
@@ -206,14 +206,19 @@ namespace base {
 // base::is_trivially_copyable will differ for these cases.
 template <typename T>
 struct is_trivially_copyable {
-#if V8_CC_MSVC
+#if V8_CC_MSVC || (__GNUC__ == 12 && __GNUC_MINOR__ <= 2)
   // Unfortunately, MSVC 2015 is broken in that std::is_trivially_copyable can
   // be false even though it should be true according to the standard.
   // (status at 2018-02-26, observed on the msvc waterfall bot).
   // Interestingly, the lower-level primitives used below are working as
   // intended, so we reimplement this according to the standard.
   // See also https://developercommunity.visualstudio.com/content/problem/
   //          170883/msvc-type-traits-stdis-trivial-is-bugged.html.
+  //
+  // GCC 12.1 and 12.2 are broken too, they are shipped by some stable Linux
+  // distributions, so the same polyfill is also used.
+  // See
+  // https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=aeba3e009b0abfccaf01797556445dbf891cc8dc
   static constexpr bool value =
       // Copy constructor is trivial or deleted.
       (std::is_trivially_copy_constructible<T>::value ||
