1368616 - Error compiling TestBlockingProcess.exe with MinGW: undefined reference to `_imp___ZN7mozilla6UnusedE'

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[Tom Ritter [:tjr]]

>  0:04.18 Executing: /usr/local/bin/i686-w64-mingw32-g++ -std=gnu++11 -mwindows -Wall -Wc++11-compat -Wempty-body -Wignored-qualifiers -Woverloaded-virtual > -Wpointer-arith -Wsign-compare -Wtype-limits -Wunreachable-code -Wwrite-strings -Wno-invalid-offsetof -Wc++14-compat -Wno-error=maybe-uninitialized > -Wno-error=deprecated-declarations -Wno-error=array-bounds -Wformat -Wno-format -fno-exceptions -fno-strict-aliasing -mms-bitfields -mstackrealign > -fno-keep-inline-dllexport -fno-rtti -fno-exceptions -fno-math-errno -pipe -g -fno-omit-frame-pointer -o TestBlockingProcess.exe /home/tom/Documents/moz/> mingw-work/just-build-4-tests/obj-mingw/xpcom/tests/tmpiRLrUx.list -mconsole -Wl,--build-id -static -Wl,--enable-stdcall-fixup -Wl,--large-address-aware > -fdiagnostics-color -luuid -lgdi32 -lwinmm -lwsock32 -luserenv -lsecur32
>  0:04.18 /home/tom/Documents/moz/mingw-work/just-build-4-tests/obj-mingw/xpcom/tests/tmpiRLrUx.list:
>  0:04.18     INPUT("TestBlockingProcess.o")
>  0:04.18     INPUT("../../mfbt/Compression.o")
>  0:04.18     INPUT("../../mfbt/Decimal.o")
>  0:04.18     INPUT("../../mfbt/Unified_cpp_mfbt0.o")
>  0:04.18     INPUT("../../mfbt/Unified_cpp_mfbt1.o")
>  0:04.18
>  0:04.18 TestBlockingProcess.o: In function `main':
>  0:04.18 /home/tom/Documents/moz/mingw-work/just-build-4-tests/xpcom/tests/TestBlockingProcess.cpp:7: undefined reference to `_imp___ZN7mozilla6UnusedE'
>  0:04.18 collect2: error: ld returned 1 exit status
>  0:04.19 /home/tom/Documents/moz/mingw-work/just-build-4-tests/config/rules.mk:713: recipe for target 'TestBlockingProcess.exe' failed
>  0:04.19 make[5]: *** [TestBlockingProcess.exe] Error 1

_imp___ZN7mozilla6UnusedE is defined here:

> File: ./mozglue/build/libmozglue.a
> 00000000 I __imp___ZN7mozilla6UnusedE

And imported like so:

> File: ./xpcom/io/FileUtilsWin.o
>          U __imp___ZN7mozilla6UnusedE
> --
> File: ./xpcom/ds/Unified_cpp_xpcom_ds0.o
>          U __imp___ZN7mozilla6UnusedE
> --
> File: ./xpcom/tests/gtest/Unified_cpp_xpcom_tests_gtest2.o
>          U __imp___ZN7mozilla6UnusedE
> --
> File: ./xpcom/tests/gtest/TestNsRefPtr.o
>          U __imp___ZN7mozilla6UnusedE
> --
> File: ./xpcom/tests/gtest/TestCOMPtr.o
>          U __imp___ZN7mozilla6UnusedE
> --
> File: ./xpcom/tests/gtest/Unified_cpp_xpcom_tests_gtest1.o
>          U __imp___ZN7mozilla6UnusedE
> --
> File: ./xpcom/tests/gtest/Unified_cpp_xpcom_tests_gtest0.o
>          U __imp___ZN7mozilla6UnusedE
> --
> File: ./xpcom/tests/TestBlockingProcess.o
>          U __imp___ZN7mozilla6UnusedE



Only applies to --enable-tests configuration.

Comment 1

[Jacek Caban]

Attachment: patch

The problem happens only with --disable-optimize builds. Such builds don't inline functions, so they need to emit the actual call to << operator (which requires mozilla::Unused). It's somehow missing for those tests, but I don't think we want such calls to ever be emitted, even in --disable-optimize builds. The attached patch fixes it by making the operator always inline.

Comment 2

[Tom Ritter [:tjr]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=8d424a26dd402b68e3b21bfda9954fd29c9271dc

I'll have to confirm it has the correct mozconfig flags though...

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/57b1aa6bfa2e
Error compiling TestBlockingProcess.exe with MinGW: undefined reference to _imp___ZN7mozilla6UnusedE r=froydnj

Comment 4

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/57b1aa6bfa2e

Comment 5

[James Cheng[:JamesCheng]]

Hi Jacek,
I'm curious about the solution of this bug,

it uses MOZ_ALWAYS_INLINE_EVEN_DEBUG to make it force inline 

But the compiling error is the unresolved external symbol which means Unused.cpp is not involving the  linkage when compiling those XPCOM tests.

Could it be a potential problem that we use the cpp under MFBT/***.cpp?

It seems the force inline attribute only supported on gcc and vc except clang [1]

So if the --disable-optimiz + clang can also reproduce this issue?


Thanks.
[1]
http://searchfox.org/mozilla-central/rev/ae94cfb36d804727dfb38f2750bfcaab4621df6e/mfbt/Attributes.h#29

Comment 6

[Jacek Caban]

clang actually supports always_inline both always_inline and __forceinline. Pure clang defines __GNUC__ and clang-cl defines _MSC_VER so it will use one variant or another, depending on which variant of clang you use.