[build bug] Modifying gumbo source doesn't cause rebuilds

[stevecheckoway]

Please describe the bug

Modifying the gumbo source files doesn't cause rake compile:nokogiri to rebuild the extension.

Help us reproduce what you're seeing

1. Compile the extension with rake compile:nokogiri
2. Touch a gumbo source file: touch gumbo-parser/src/util.h
3. Recompile the extension with rake compile:nokogiri

$ bundle exec rake compile:nokogiri
/usr/bin/make install target_prefix=
install -c -p -m 755 nokogiri.bundle /Users/steve/programming/nokogiri/lib/nokogiri
cp tmp/arm64-darwin21/nokogiri/3.1.2/nokogiri.bundle tmp/arm64-darwin21/stage/lib/nokogiri/nokogiri.bundle
$ touch gumbo-parser/src/util.h
$ bundle exec rake compile:nokogiri
cp gumbo-parser/src/util.h tmp/arm64-darwin21/stage/gumbo-parser/src/util.h
/usr/bin/make install target_prefix=
install -c -p -m 755 nokogiri.bundle /Users/steve/programming/nokogiri/lib/nokogiri
cp tmp/arm64-darwin21/nokogiri/3.1.2/nokogiri.bundle tmp/arm64-darwin21/stage/lib/nokogiri/nokogiri.bundle

Note that the extension was already compiled for the first invocation so nothing needed to be done. In the second compilation, it also thinks there's nothing to do. (The same holds true if you actually modify the file, not merely touch it, but touching is traditionally sufficient for build systems.)

Expected behavior

I expect the gumbo library to be recompiled (or at least the parts of it that were changed) and the nokogiri.bundle to be rebuilt.

Environment

• I'm building the main branch.
• ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [arm64-darwin21]
• macOS 13.0.1

[flavorjones]

Thanks for opening this issue up, this has been mildly annoying me, too.

It's a side effect of how I ended up implementing the libgumbo build, as a separate library and not part of the extension -- using the packaged_tarball strategy.

Maybe that was a mistake, especially given your notes about link-time optimization in #2331, and I should have picked packaged_source instead. I'll play with it a bit and see if I can convince myself to do it this way.

[stevecheckoway]

This is definitely not a priority. I just noticed it and thought I'd make a note of it.