[SR-14314] [Windows] Linker errors building libdispatch for x86

[triplef]

Previous ID	SR-14314
Radar	None
Original Reporter	@triplef
Type	Bug

Attachment: Download

Environment

• Clang 11.0.1

• Visual Studio 2019

• Windows 10 1909

Additional Detail from JIRA

Votes	0
Component/s	libdispatch
Labels	Bug
Assignee	@compnerd
Priority	Medium

md5: b4d8ba04a01d22ce72a059fa5b24e547

relates to:

• SR-11873 [Windows] building the toolchain fails

Issue Description:

I'm trying to build libdispatch on Windows, which works fine for x64 (in a "x64 Native Tools Command Prompt for VS 2019").

However, building for x86 fails due to various linker errors for BlocksRuntime (full CMake invocation + CMake output + build output attached):

lld-link: error: <root>: undefined symbol: __DllMainCRTStartup@12
lld-link: error: undefined symbol: ___security_cookie
>>> referenced by C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\ucrt\stdio.h:1781
>>>               src\BlocksRuntime\CMakeFiles\BlocksRuntime.dir\runtime.c.obj:(_sprintf)
...lld-link: error: undefined symbol: @__security_check_cookie@4
>>> referenced by C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\ucrt\stdio.h:1792
>>>               src\BlocksRuntime\CMakeFiles\BlocksRuntime.dir\runtime.c.obj:(_sprintf)
...lld-link: error: undefined symbol: __declspec(dllimport) _malloc
>>> referenced by C:\libdispatch\src\BlocksRuntime\runtime.c:371
>>>               src\BlocksRuntime\CMakeFiles\BlocksRuntime.dir\runtime.c.obj:(__Block_copy_internal)
...lld-link: error: undefined symbol: _memmove
>>> referenced by C:\libdispatch\src\BlocksRuntime\runtime.c:373
>>>               src\BlocksRuntime\CMakeFiles\BlocksRuntime.dir\runtime.c.obj:(__Block_copy_internal)
...lld-link: error: undefined symbol: __declspec(dllimport) __wassert
>>> referenced by C:\libdispatch\src\BlocksRuntime\runtime.c:482
>>>               src\BlocksRuntime\CMakeFiles\BlocksRuntime.dir\runtime.c.obj:(__Block_byref_release)lld-link: error: undefined symbol: __declspec(dllimport) ___stdio_common_vsprintf
>>> referenced by C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\ucrt\stdio.h:1390
>>>               src\BlocksRuntime\CMakeFiles\BlocksRuntime.dir\runtime.c.obj:(__vsnprintf_l)lld-link: error: undefined symbol: _free
>>> referenced by src\BlocksRuntime\CMakeFiles\BlocksRuntime.dir\runtime.c.obj:(__Block_deallocator)

I am building in a "x86 Native Tools Command Prompt for VS 2019". Even then I had to also specify CFLAGS/CXXFLAGS=-m32 for CMake to not try to target x64 to begin with.

SR-11873 is similar.

[typesanitizer]

cc @compnerd

[triplef]

The issue can also be reproduced using either vcvarsall.bat x86 or vcvarsall.bat x64_x86 instead of the Native Tools Command Prompt.

[alexchandel]

What's the solution for <root>: undefined symbol: __DllMainCRTStartup? What lib was missing?

[triplef]

I haven’t found a solution for this issue so far.

[compnerd]

I'm going to close off this issue. https://dev.azure.com/compnerd/swift-build/_build/results?buildId=60189&view=logs&j=dd7b6b62-9f28-5f94-8c40-5f429eddf697&t=59165692-3d8b-580c-d072-b191af61d4c2 shows a valid build for x86. There was a time where the x86 build of libdispatch didn't work, but I believe all the issues have been resolved. Yes, this is a bit trickier to get right, but the following should give you a working build:
https://github.com/compnerd/swift-build/blob/master/build.cmd#L502
https://github.com/compnerd/swift-build/blob/master/build.cmd#L620-L639
with appropriate modifications of course.

FTR, the undefined symbol __DllMainCRTStartup is going to be fulfilled by msvcrt.lib.