Fixed shared windows builds of test targets

[h-vetinari]

Regarding #1407

[derekmauro]

How was this tested? It doesn't appear to work.

T:\src\github\abseil-cpp\absl/strings/internal/cordz_handle.h(111,32): error C2220: the following warning is treated as an error [T:\src\github\abseil-cpp\build\absl\abseil_dll.vcxproj]
T:\src\github\abseil-cpp\absl/strings/internal/cordz_handle.h(111,32): warning C4251: 'absl::cord_internal::CordzHandle::global_queue_': struct 'absl::cord_internal::CordzHandle::Queue' needs to have dll-interface to be used by clients of class 'absl::cord_internal::CordzHandle'

I'm guessing it is a simple fix to add ABSL_DLL to the variable in the error message.

[h-vetinari]

the following warning is treated as an error

There's your answer. 😅

I didn't build with (the equivalent of) -Werror. As you say, it's most likely a couple ABSL_DLL markers that need to be added.

Without this PR. compilation fails hard. So we can say the patches here are necessary but not sufficient.

[h-vetinari]

I'm guessing it is a simple fix to add ABSL_DLL to the variable in the error message.

Adding ABSL_DLL to cord_internal::CordzHandle::Queue leads to:

absl/strings/internal/cordz_handle.h(89): warning C4251: 'absl::lts_20230125::cord_internal::CordzHandle::Queue::mutex': class 'absl::lts_20230125::base_internal::SpinLock' needs to have dll-interface to be used by clients of struct 'absl::lts_20230125::cord_internal::CordzHandle::Queue'
absl/strings/internal/cordz_handle.h(90): warning C4251: 'absl::lts_20230125::cord_internal::CordzHandle::Queue::dq_tail': struct 'std::atomic<absl::lts_20230125::cord_internal::CordzHandle *>' needs to have dll-interface to be used by clients of struct 'absl::lts_20230125::cord_internal::CordzHandle::Queue'

Further adding ABSL_DLL to dq_tail then leads to:

absl/strings/internal/cordz_handle.h(90): error C2071: 'absl::lts_20230125::cord_internal::CordzHandle::Queue::dq_tail': illegal storage class
absl/strings/internal/cordz_handle.h(90): warning C4251: 'absl::lts_20230125::cord_internal::CordzHandle::Queue::dq_tail': struct 'std::atomic<absl::lts_20230125::cord_internal::CordzHandle *>' needs to have dll-interface to be used by clients of struct 'absl::lts_20230125::cord_internal::CordzHandle::Queue'

The second warning is actually interesting here because it talks about a struct, whereas the definition is:

std::atomic<CordzHandle*> dq_tail ABSL_GUARDED_BY(mutex){nullptr};

I presume the ABSL_GUARDED_BY annotation may actually turn that whole thing into a struct behind the scenes to carry information about the mutex? No idea how to declare that struct with ABSL_DLL in a way that preserves (the windows equivalent of) __attribute__((guarded_by(x)))

[derekmauro]

I have a different fix for this that I am testing. It involves not exposing some things in headers to avoid the need for ABSL_DLL. Hopefully it will make it to GitHub soon.

[h-vetinari]

I have a different fix for this that I am testing. It involves not exposing some things in headers to avoid the need for ABSL_DLL. Hopefully it will make it to GitHub soon.

That's great news, thanks a lot! Could you let us know here once that happens please? :)

[derekmauro]

Please give 3aa3377 a try. I think either fixes your issue or gets us closer to a fix. It's possible some some ABSL_DLL annotations are still required.

[h-vetinari]

Please give 3aa3377 a try. I think either fixes your issue or gets us closer to a fix. It's possible some some ABSL_DLL annotations are still required.

Thanks! Giving this a shot in conda-forge/abseil-cpp-feedstock#60.

[h-vetinari]

Please give 3aa3377 a try. I think either fixes your issue or gets us closer to a fix. It's possible some some ABSL_DLL annotations are still required.

Thanks! Giving this a shot in conda-forge/abseil-cpp-feedstock#60.

Back to failing with the missing vftable, which I had been battling in conda-forge/abseil-cpp-feedstock#58 as well, and which ended up being "solved" by adding ABSL_DLL to the class.

[370/447] Linking CXX executable bin\absl_cordz_handle_test.exe
FAILED: bin/absl_cordz_handle_test.exe 
cmd.exe /C "cd . && D:\bld\abseil-split_1683936617505\_build_env\Library\bin\cmake.exe -E vs_link_exe --intdir=absl\strings\CMakeFiles\absl_cordz_handle_test.dir --rc=C:\PROGRA~2\WI3CF2~1\10\bin\100226~1.0\x64\rc.exe --mt=C:\PROGRA~2\WI3CF2~1\10\bin\100226~1.0\x64\mt.exe --manifests  -- C:\PROGRA~1\MICROS~2\2022\ENTERP~1\VC\Tools\MSVC\1429~1.301\bin\HostX64\x64\link.exe /nologo absl\strings\CMakeFiles\absl_cordz_handle_test.dir\internal\cordz_handle_test.cc.obj  /out:bin\absl_cordz_handle_test.exe /implib:absl\strings\absl_cordz_handle_test.lib /pdb:bin\absl_cordz_handle_test.pdb /version:0.0 /machine:x64 /INCREMENTAL:NO /subsystem:console  absl\abseil_test_dll.lib  D:\bld\abseil-split_1683936617505\_h_env\Library\lib\gmock_main.lib  absl\abseil_dll.lib  kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib && cd ."
LINK: command "C:\PROGRA~1\MICROS~2\2022\ENTERP~1\VC\Tools\MSVC\1429~1.301\bin\HostX64\x64\link.exe /nologo absl\strings\CMakeFiles\absl_cordz_handle_test.dir\internal\cordz_handle_test.cc.obj /out:bin\absl_cordz_handle_test.exe /implib:absl\strings\absl_cordz_handle_test.lib /pdb:bin\absl_cordz_handle_test.pdb /version:0.0 /machine:x64 /INCREMENTAL:NO /subsystem:console absl\abseil_test_dll.lib D:\bld\abseil-split_1683936617505\_h_env\Library\lib\gmock_main.lib absl\abseil_dll.lib kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib /MANIFEST /MANIFESTFILE:bin\absl_cordz_handle_test.exe.manifest" failed (exit code 1120) with the following output:
cordz_handle_test.cc.obj : error LNK2019: unresolved external symbol "const absl::lts_20230125::cord_internal::CordzHandle::`vftable'" (??_7CordzHandle@cord_internal@lts_20230125@absl@@6B@) referenced in function "public: __cdecl absl::lts_20230125::cord_internal::CordzHandle::CordzHandle(void)" (??0CordzHandle@cord_internal@lts_20230125@absl@@QEAA@XZ)

bin\absl_cordz_handle_test.exe : fatal error LNK1120: 1 unresolved externals

[derekmauro]

I pulled in #1115 with the missing ABSL_DLL. Is there anything left to do?

[h-vetinari]

I pulled in #1115 with the missing ABSL_DLL. Is there anything left to do?

Thanks! The build based on your commit did already include (the equivalent of) #1115, so I'm pretty sure it's still not working properly. Though I admit I don't understand what might be the pertinent differences between our respective build setups.