1363009 - Vector.h: fails to build with gcc 7 on -Werror=strict-aliasing

Status: RESOLVED FIXED

(Core :: MFBT, defect)

Description

[Sylvestre Ledru [:Sylvestre]]

^~
In file included from /root/firefox-gcc-last/obj-x86_64-pc-linux-gnu/dist/include/mozilla/ArrayUtils.h:14:0,
                 from /root/firefox-gcc-last/obj-x86_64-pc-linux-gnu/dist/include/mozilla/RangedPtr.h:15,
                 from /root/firefox-gcc-last/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Range.h:10,
                 from /root/firefox-gcc-last/obj-x86_64-pc-linux-gnu/dist/include/js/CharacterEncoding.h:10,
                 from /root/firefox-gcc-last/js/src/jscntxt.h:14,
                 from /root/firefox-gcc-last/js/src/vm/RegExpObject.h:15,
                 from /root/firefox-gcc-last/js/src/builtin/RegExp.h:10,
                 from /root/firefox-gcc-last/js/src/builtin/RegExp.cpp:7:
/root/firefox-gcc-last/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Vector.h: In instantiation of 'mozilla::Vector<T, N, AllocPolicy>::~Vector() [with T = JS::Value; long unsigned int MinInlineCapacity = 8; AllocPolicy = js::TempAllocPolicy]':
/root/firefox-gcc-last/obj-x86_64-pc-linux-gnu/dist/include/js/GCVector.h:36:7:   required from here
/root/firefox-gcc-last/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Vector.h:831:45: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
   MOZ_ASSERT_IF(usingInlineStorage(), mTail.mCapacity == kInlineCapacity); \
                                       ~~~~~~^
/root/firefox-gcc-last/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Assertions.h:402:69: note: in definition of macro 'MOZ_VALIDATE_ASSERT_CONDITION_TYPE'
      static_assert(mozilla::detail::AssertionConditionType<decltype(x)>::isValid, \
                                                                     ^
/root/firefox-gcc-last/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Assertions.h:435:39: note: in expansion of macro 'MOZ_ASSERT_HELPER1'
 #define MOZ_RELEASE_ASSERT_GLUE(a, b) a b
                                       ^
/root/firefox-gcc-last/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Assertions.h:437:3: note: in expansion of macro 'MOZ_RELEASE_ASSERT_GLUE'
   MOZ_RELEASE_ASSERT_GLUE( \
   ^~~~~~~~~~~~~~~~~~~~~~~
/root/firefox-gcc-last/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Assertions.h:442:27: note: in expansion of macro 'MOZ_RELEASE_ASSERT'
 #  define MOZ_ASSERT(...) MOZ_RELEASE_ASSERT(__VA_ARGS__)
                           ^~~~~~~~~~~~~~~~~~
/root/firefox-gcc-last/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Assertions.h:466:10: note: in expansion of macro 'MOZ_ASSERT'
          MOZ_ASSERT(expr); \
          ^~~~~~~~~~
/root/firefox-gcc-last/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Vector.h:831:3: note: in expansion of macro 'MOZ_ASSERT_IF'
   MOZ_ASSERT_IF(usingInlineStorage(), mTail.mCapacity == kInlineCapacity); \
   ^~~~~~~~~~~~~
/root/firefox-gcc-last/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Vector.h:904:3: note: in expansion of macro 'MOZ_REENTRANCY_GUARD_ET_AL'
   MOZ_REENTRANCY_GUARD_ET_AL;
   ^~~~~~~~~~~~~~~~~~~~~~~~~~

Comment 1

[Chris Peterson [:cpeterson]]

Do we support -fstrict-aliasing?

Comment 2

[Andi [:andi]]

Most likely we shouldn't compile this with -fstrict-aliasing, I think we should use: -fno-strict-aliasing

Comment 3

[Andi [:andi]]

More info can be found here why we don't support yet strict-aliasing: https://bugzilla.mozilla.org/show_bug.cgi?id=414641

Comment 4

[Sylvestre Ledru [:Sylvestre]]

ok, we should disable this option for real then and for everyone

Comment 5

[Andi [:andi]]

Attachment: Bug 1363009 - disable strict-aliasing for gcc in js/src.

Review commit: https://reviewboard.mozilla.org/r/139686/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/139686/

Comment 6

[Benjamin Bouvier [:bbouvier] (inactive)]

Comment on attachment 8868073 [details]
Bug 1363009 - disable strict-aliasing for gcc in js/src.

Sorry I am not comfortable reviewing this; maybe a build peer would be more appropriate here.

Comment 7

[Steve Fink [:sfink] [:s:]]

Comment on attachment 8868073 [details]
Bug 1363009 - disable strict-aliasing for gcc in js/src.

https://reviewboard.mozilla.org/r/139686/#review144258

A little sad, but I agree with the change.

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/48ff50f0db50
disable strict-aliasing for gcc in js/src. r=sfink

Comment 9

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/48ff50f0db50