1287991 - "Multiple definition of" errors when compiling Firefox with Clang and -flto

Status: RESOLVED INVALID

(Firefox Build System :: General, defect)

Description

[Enes Göktaş [:egoktas]]

'multiple definition of' errors are thrown when compiling Firefox with Clang. The {C,CXX,LD}FLAGS include the options -flto and either -O1 or -O2(see attached mozconfig files). Clang build must include LLVMgold.so. Also the gold linker (ld.gold) has to be set as the linker.

When compiling with -O1, a multiple definition error is thrown when libbrowsercomps.so is being built. Conflict happens between libxpcomglue_s.a and fallible.o. 
When compiling with -O2, multiple definition errors are thrown when libxul.so is being built. In this case the conflict happens between libjs_static.a and the following list of object files:
- modules/zlib/src/adler32.o
- modules/zlib/src/compress.o
- modules/zlib/src/crc32.o
- modules/zlib/src/deflate.o
- modules/zlib/src/gzclose.o
- modules/zlib/src/gzlib.o
- modules/zlib/src/gzread.o
- modules/zlib/src/gzwrite.o
- modules/zlib/src/inffast.o
- modules/zlib/src/inflate.o
- modules/zlib/src/inftrees.o
- modules/modules/zlib/src/trees.o
- modules/zlib/src/uncompr.o
- modules/zlib/src/zutil.o

Please see the attached error files for more details.

Versions used:
Firefox: git log -1, commit sha1: cab4a5aa0a76064577e964f55651d904da8c1091
OS: Ubuntu 14.04.4 LTS
LLVM/Clang: 3.8.1
ld.gold: binutils version 2.24

Comment 1

[Enes Göktaş [:egoktas]]

Attachment: mozconfig_with_O1

Comment 2

[Enes Göktaş [:egoktas]]

Attachment: mozconfig_with_O2

Comment 3

[Enes Göktaş [:egoktas]]

Attachment: multiple_definition_error_libbrowsercomps.so.txt

Comment 4

[Enes Göktaş [:egoktas]]

Attachment: multiple_definition_error_libxul.so.txt

Comment 5

[Kim Moir [:kmoir] ET]

Is this still an issue?  There has been a lot of progress on using Clang in Linux builds recently.

See
https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Build_Instructions/Compiling_Firefox_With_Clang_On_Linux

and bug 1480631

Comment 6

[Kim Moir [:kmoir] ET]

closing, please reopen if it is still an issue