[PATCH] D94536: [dsymutil] Warn on timestmap mismatch between object file and debug map

Tue Jan 19 15:48:12 PST 2021

JDevlieghere added a comment.

In D94536#2507008 <https://reviews.llvm.org/D94536#2507008>, @sberg wrote:

> As also reported at https://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20210118/872711.html "Re: [llvm] 48d2068 <https://reviews.llvm.org/rG48d2068fb738302b9fba91c9bf8e4b051c3909eb> - [dsymutil] Warn on timestmap mismatch between object file and debug map" about the re-revert https://github.com/llvm/llvm-project/commit/48d2068fb738302b9fba91c9bf8e4b051c3909eb "[dsymutil] Warn on timestmap mismatch between object file and debug map" (but for which there appears to be no Phabricator review of its own):
>
> I have no idea what this warning is all about, and what exactly triggers it, but it looks like it breaks the
>
>   # Check if the C compiler supports the "visibility" function attribute
>   # If supported, defines HAVE_FUNC_ATTRIBUTE_VISIBILITY
>   AX_GCC_FUNC_ATTRIBUTE(visibility)
>
> configure check used by Little-CMS (https://github.com/mm2/Little-CMS/blob/a0fc38ddd55a0341dafa7414ac624c1f09271401/configure.ac#L70; e.g. built as part of building LibreOffice), when building on macOS:
>
>   configure:15908: checking for __attribute__((visibility))
>   configure:15930: /Users/stephan/Software/llvm/inst/bin/clang -m64 -mmacosx-version-min=10.15 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.1.sdk -fno-sanitize-recover=all -ferror-limit=0 -o conftest  -ggdb2 -Xclang -debug-info-kind=constructor -O0 -fstrict-aliasing -fstrict-overflow  -I/Users/stephan/Software/lo/core/include  -I/Users/stephan/Software/adoptopenjdk.net/OpenJDK15U-jdk_x64_mac_hotspot_15.0.1_9/jdk-15.0.1+9/Contents/Home/include  -I/Users/stephan/Software/adoptopenjdk.net/OpenJDK15U-jdk_x64_mac_hotspot_15.0.1_9/jdk-15.0.1+9/Contents/Home/include/darwin  conftest.c  >&5
>   warning: /Users/stephan/Software/lo/TMPDIR/conftest-01e065.o: timestamp mismatch between object file (2021-01-18 19:22:51.045749227) and debug map (2021-01-18 19:22:51.000000000)
>   warning: /Users/stephan/Software/lo/TMPDIR/conftest-01e065.o: timestamp mismatch between object file (2021-01-18 19:22:51.045749227) and debug map (2021-01-18 19:22:51.000000000)
>   configure:15930: $? = 0
>   configure:15943: result: no
>
> That is, the warning output apparently confuses the AX_GCC_FUNC_ATTRIBUTE logic and makes it erroneously assume that Clang does not support __attribute__((visibility)).

Seems like a mismatch in precision between the timestamp in the debug map and the one return from the filesystem. I don't think we need that much precision so i'll truncate it to seconds.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D94536/new/

https://reviews.llvm.org/D94536