Build failed on 32-bit arm platform

[JackBoosY]

Describe the bug

A few months ago, I received an issue, that is, Abseil cannot be built on the 32-bit arm platform using vcpkg (microsoft/vcpkg#11820), so I submitted a PR (microsoft/vcpkg#11827) to fix this issue.
Unfortunately, this PR broke the build of the 64-bit arm platform.
After communicating with the cctz official (google/cctz#173), they believe that this is a setting error in abseil that caused the symbol mismatch problem.
Error log:

time_zone_info.obj : error LNK2001: unresolved external symbol "class std::unique_ptr<class absl::time_internal::cctz::ZoneInfoSource,struct std::default_delete<class absl::time_internal::cctz::ZoneInfoSource> > (__cdecl* absl::time_internal::cctz_extension::zone_info_source_factory)(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &,class std::function<class std::unique_ptr<class absl::time_internal::cctz::ZoneInfoSource,struct std::default_delete<class absl::time_internal::cctz::ZoneInfoSource> > __cdecl(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)> const &)" (?zone_info_source_factory@cctz_extension@time_internal@absl@@3P6A?AV?$unique_ptr@VZoneInfoSource@cctz@time_internal@absl@@U?$default_delete@VZoneInfoSource@cctz@time_internal@absl@@@std@@@std@@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@5@AEBV?$function@$$A6A?AV?$unique_ptr@VZoneInfoSource@cctz@time_internal@absl@@U?$default_delete@VZoneInfoSource@cctz@time_internal@absl@@@std@@@std@@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@2@@Z@5@@ZEA) [C:\Users\ComputerName\testx\ProjectForWindows\vcpkg\buildtrees\abseil\arm64-uwp-dbg\absl\abseil_dll.vcxproj]

And if I only use the cctz official patch (only modify #elif defined(_M_IA_64) to #elif defined(_M_IA_64) || defined(_M_AMD64) || \ defined(_M_ARM64)), I will encounter the following error when building arm-windows:

time_zone_info.cc.obj : error LNK2001: unresolved external symbol "class std::unique_ptr<class absl::lts_2020_09_23::time_internal::cctz::ZoneInfoSource,struct std::default_delete<class absl::lts_2020_09_23::time_internal::cctz::ZoneInfoSource> > (__cdecl* absl::lts_2020_09_23::time_internal::cctz_extension::zone_info_source_factory)(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &,class std::function<class std::unique_ptr<class absl::lts_2020_09_23::time_internal::cctz::ZoneInfoSource,struct std::default_delete<class absl::lts_2020_09_23::time_internal::cctz::ZoneInfoSource> > __cdecl(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)> const &)" (?zone_info_source_factory@cctz_extension@time_internal@lts_2020_09_23@absl@@3P6A?AV?$unique_ptr@VZoneInfoSource@cctz@time_internal@lts_2020_09_23@absl@@U?$default_delete@VZoneInfoSource@cctz@time_internal@lts_2020_09_23@absl@@@std@@@std@@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@6@ABV?$function@$$A6A?AV?$unique_ptr@VZoneInfoSource@cctz@time_internal@lts_2020_09_23@absl@@U?$default_delete@VZoneInfoSource@cctz@time_internal@lts_2020_09_23@absl@@@std@@@std@@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@2@@Z@6@@ZA)

Do you have any ideas?

Steps to reproduce the bug

1. git clone https://github.com/microsoft/vcpkg.git
2. .\bootstrap-vcpkg.bat
3. .\vcpkg install abseil:arm64-uwp

What version of Abseil are you using?
2020-03-03

What operating system and version are you using
Windows 10 64bit
vcpkg latest

What compiler and version are you using?
Visual Studio 2017 latest build

What build system are you using?
vcpkg (cmake 3.18.2 with Visual Studio 2017)
Additional context

Thanks.

[JackBoosY]

I've revert my changes about the arm32 build.
Can anyone fix this issue here?

[tusharb86]

@JackBoosY I think this patch might be the way to make the linker happy for both arm32 and arm64. @vslashg Is there any issue with merging this patch? I'm happy to open a PR and help get this through. Thanks!

diff --git a/absl/time/internal/cctz/src/zone_info_source.cc b/absl/time/internal/cctz/src/zone_info_source.cc
index 7209533..5ab5a59 100644
--- a/absl/time/internal/cctz/src/zone_info_source.cc
+++ b/absl/time/internal/cctz/src/zone_info_source.cc
@@ -65,7 +65,7 @@ ZoneInfoSourceFactory zone_info_source_factory __attribute__((weak)) =
 extern ZoneInfoSourceFactory zone_info_source_factory;
 extern ZoneInfoSourceFactory default_factory;
 ZoneInfoSourceFactory default_factory = DefaultFactory;
-#if defined(_M_IX86)
+#if defined(_M_IX86) || defined(_M_ARM)
 #pragma comment(                                                                                                         \
     linker,                                                                                                              \
     "/alternatename:?zone_info_source_factory@cctz_extension@time_internal@" ABSL_INTERNAL_MANGLED_NS                    \
@@ -83,8 +83,7 @@ ZoneInfoSourceFactory default_factory = DefaultFactory;
     "@@U?$default_delete@VZoneInfoSource@cctz@time_internal@" ABSL_INTERNAL_MANGLED_NS                                   \
     "@@@std@@@std@@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@2@@Z@" ABSL_INTERNAL_MANGLED_BACKREFERENCE \
     "@@ZA")
-#elif defined(_M_IA_64) || defined(_M_AMD64) || defined(_M_ARM) || \
-    defined(_M_ARM64)
+#elif defined(_M_IA_64) || defined(_M_AMD64) || defined(_M_ARM64)
 #pragma comment(                                                                                                          \
     linker,                                                                                                               \
     "/alternatename:?zone_info_source_factory@cctz_extension@time_internal@" ABSL_INTERNAL_MANGLED_NS                     \

[NancyLi1013]

Thanks for your fix @tusharb86.

@derekmauro, @vslashg Could you please help confirm if the patch from @tusharb86 is acceptable?

I have verified that this can solve the problem posted by @JackBoosY

[derekmauro]

This patch looks plausible to me. I'll run it though some tests and see what happens.

[derekmauro]

Fixed by 3b22e57.

[JackBoosY]

Thanks guys!