Improvements to the pkg-config file #26
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
When m4ri is compiled with PNG support, it exposes the two new symbols mzd_from_png and mzd_to_png via m4ri/io.h. But neither of those functions takes any libpng types as an argument, and so a program being linking against m4ri should not need to include -lpng in its link flags.
The -fopenmp (or equivalent) flag should not be present in Cflags, because it causes programs being linked against m4ri to be compiled with OpenMP support, and that may not be intended. For example, this causes runtime crashes in SageMath built with meson: while -fopenmp from m4ri is used at compile time, libgomp is ultimately not linked in because the build system doesn't think we're using OpenMP. As a result, $OPENMP_FLAGS flags are more appropriate to include when linking than compiling. Moreover, the OpenMP library dependency (on libgomp or equivalent) should be private for the same reason libpng is: none of its symbols are directly exposed to users of m4ri.
|
Why do you still keep libpng's cflags in? |
If the |
dimpase
approved these changes
Jan 22, 2025
|
OK |
|
Thanks! |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Two small improvements to
m4ri.pc:libpng becomes an internal (
Requires.private) dependency. I've looked at the code, and I don't think any symbols from libpng are leaked to consumers. In other words, someone linking their program to m4ri does not need to supply-lpng. This change prevents the-lpngfrom being output bypkg-config --libs m4ri.The OpenMP flags are applied to static linking only. This was my original motivation for digging into this file. My copy of sage was being compiled (but not linked!) with
-fopenmpbecause that flag appears in the pkg-config output for m4ri. The result of course crashes due to missing libgomp symbols. TheOPENMP_FLAGSare applied to linking to (only) to avoid this issue, and made private for the same reason we made libpng private.Resolves:
CC: @kiwifb, @dimpase, @tornaria, @arojas, @isuruf