Bug 271108 – REGRESSION(274077@main): failure to build on i586 (and likely other 32bit arches): static assertion failed: Timer should stay small

• Component: WebKitGTK
• Status: RESOLVED FIXED

[Dominique Leuenberger]

[ 1646s] In file included from /home/abuild/rpmbuild/BUILD/webkitgtk-2.44.0/build/WebCore/DerivedSources/unified-sources/UnifiedSource-3c72abbe-12.cpp:2:
[ 1646s] /home/abuild/rpmbuild/BUILD/webkitgtk-2.44.0/Source/WebCore/platform/Timer.cpp:269:29: error: static assertion failed: Timer should stay small
[ 1646s]   269 | static_assert(sizeof(Timer) == sizeof(SameSizeAsTimer), "Timer should stay small");
[ 1646s]       |               ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
[ 1646s] /home/abuild/rpmbuild/BUILD/webkitgtk-2.44.0/Source/WebCore/platform/Timer.cpp:269:29: note: the comparison reduces to ‘(40 == 36)’
[ 1646s] /home/abuild/rpmbuild/BUILD/webkitgtk-2.44.0/Source/WebCore/platform/Timer.cpp:275:46: error: static assertion failed: DeferrableOneShotTimer should stay small
[ 1646s]   275 | static_assert(sizeof(DeferrableOneShotTimer) == sizeof(SameSizeAsDeferrableOneShotTimer), "DeferrableOneShotTimer should stay small");
[ 1646s]       |               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[Dominique Leuenberger]

Version 2.43.4 was the last I tested and that still built successfylly

[Michael Catanzaro]

I think SameSizeAsTimer is missing the size of the bitfields, which don't get compacted on 32-bit architectures. Let me test it...

[Michael Catanzaro]

Hey Ryosuke, are you OK with this? I will create a pull request soon.

(Alternatively, we could put the uint8_t at the bottom of the struct by reordering the Timer data members.)

diff --git a/Source/WebCore/platform/Timer.cpp b/Source/WebCore/platform/Timer.cpp
index 4f7c0f5c39ca..0f3734cca247 100644
--- a/Source/WebCore/platform/Timer.cpp
+++ b/Source/WebCore/platform/Timer.cpp
@@ -263,7 +263,11 @@ struct SameSizeAsTimer {
 
     WeakPtr<TimerAlignment> timerAlignment;
     double times[2];
-    void* pointers[3];
+    void* pointers[2];
+#if CPU(ADDRESS32)
+    uint8_t bitfields;
+#endif
+    void* pointer;
 };
 
 static_assert(sizeof(Timer) == sizeof(SameSizeAsTimer), "Timer should stay small");

[Michael Catanzaro]

Pull request: https://github.com/WebKit/WebKit/pull/26053

[EWS]

Committed 276282@main (2922af379dc7): <https://commits.webkit.org/276282@main>

Reviewed commits have been landed. Closing PR #26053 and removing active labels.