llvm-config --system-libs prints entire libxml2 path

[vinsonlee]

Bugzilla Link	44179
Resolution	FIXED
Resolved on	Feb 28, 2020 03:12
Version	trunk
OS	All
Blocks	#43900
CC	@compnerd,@zmodem

Extended Description

llvm-config --system-libs now prints the entire libxml2 path.

Before
$ llvm-config --system-libs
-lz -lrt -ldl -ltinfo -lpthread -lm -lxml2

Now
$ llvm-config --system-libs
-lz -lrt -ldl -ltinfo -lpthread -lm -l/usr/lib/x86_64-linux-gnu/libxml2.so

This leads to linking errors if depending on llvm-config --system-libs during compilation.
/usr/bin/ld: cannot find -l/usr/lib/x86_64-linux-gnu/libxml2

This new behavior is introduced with these llvm-10 commits.

commit cfcfd8a
Author: Saleem Abdulrasool compnerd@compnerd.org
Date: Wed Nov 27 12:55:46 2019 -0800

build: avoid cached literals being linked against

If the value of the LibXml2 search is cached, it can cause an errant
link against LIBXML2_LIBRARIES-NOTFOUND if libxml2 is not found. Add
a guard against this.  Should repair the build bots.

commit 340e7c0
Author: Saleem Abdulrasool compnerd@compnerd.org
Date: Wed Nov 27 12:34:36 2019 -0800

build: avoid hardcoding the libxml2 library name

FindLibXml2 will set the LIBXML2_LIBRARIES variable to the libraries that
we must link against. This will be an empty string if libxml2 is not
found. Avoid hardcoding the library name as xml2 in the configuration.
Simplify the usage in the WindowsManifest library.

[zmodem]

Saleem, have you had a chance to take a look?

[zmodem]

Saleem, have you had a chance to take a look?

Saleem: Ping?

[zmodem]

Saleem: ping 2.

This seems like a problematic regression from 9 to 10.

[vinsonlee]

The regressing commit was reverted.

commit abe8de2
Author: Saleem Abdulrasool compnerd@compnerd.org
Date: Tue Dec 3 09:27:14 2019 -0800

Revert "Temporarily revert "build: avoid hardcoding the libxml2 library name""

This reverts commit 2e75681b55ab55301022533b203269f5f3d6f909.  Restore
the clean up change.  The underlying CMake issue was resolved in
372ad32734ecb455f9fb4d0601229ca2dfc78b66.

[zmodem]

The regressing commit was reverted.

commit abe8de2
Author: Saleem Abdulrasool compnerd@compnerd.org
Date: Tue Dec 3 09:27:14 2019 -0800

Revert "Temporarily revert "build: avoid hardcoding the libxml2 library

name""

This reverts commit 2e75681b55ab55301022533b203269f5f3d6f909.  Restore
the clean up change.  The underlying CMake issue was resolved in
372ad32734ecb455f9fb4d0601229ca2dfc78b66.

I think that's the revert of a revert.

From what I understand, the problem is still there.

Saleem, are you looking into this at all?

[compnerd]

Should be addressed in c3595d1

[compnerd]

Note that zlib has a similar issue that Petr has a patch outstanding for.

[slacka]

Reopening to track for 10.x backport.

[zmodem]

Should be addressed in c3595d1

Thanks! Pushed to 10.x as 73c53e6

Note that zlib has a similar issue that Petr has a patch outstanding for.

That's Bug 44780 / https://reviews.llvm.org/D74176
I'll ping it some more.

[zmodem]

mentioned in issue #43900

[andrewrk]

mentioned in issue llvm/llvm-bugzilla-archive#44780