Fix --program-suffix resulting in invalid symlink

[wismill]

Please read Github PR Conventions and then fill in one of these two templates.

---

Template Α: This PR modifies behaviour or interface

Include the following checklist in your PR:

• Patches conform to the coding conventions.
• Any changes that could be relevant to users have been recorded in the changelog.
• The documentation has been updated, if necessary.
• Manual QA notes have been included.
• Tests have been added. (Ask for help if you don’t know how to write them! Ask for an exemption if tests are too complex for too little coverage!)

---

Fixes #9919
Fixes #8823

Based on this comment.

It took me a lot of time to understand where to look at and I am still unsure this fix does not introduce side effects. I would need some guidance if improvements are needed.

[fendor]

Thanks for tackling this very annoying issue! I am wondering, whether it would be easy to add a regression test that makes sure this doesn't break again, e.g. a PackageTests/ConfigProgTest which installs a local executable with --program-suffix into the current directory and simply tests, whether the binary can be executed?

[wismill]

I have not seen that somebody pushed some commits before force-pushing… Was it just a rebase?

[wismill]

Updated code: fix --program-prefix as well, add a test for both affix options and both --install-methods. I think it fixes #8823 as well.

Reworked commit message for full explanation:

Currently the options --program-{prefix,suffix} for cabal install
affects the name of the file in the install directory and the
executable name in the store. The installation fails:

• If using --install-method=symlink, the target of the symlink is
  not affected by the affix options and it results in an invalid symlink.
• If using --install-method=copy, the copy fails because the source
  is not found.

Another issue is that it affects the computation of the hash of the
build directory in the store, resulting in needless rebuild when using
successively different affix options.

Fixed by making the name of the executable in the store canonical, i.e.
always ignoring the program affix options.

Added a test for all the combinations of --install-method and program
affixes options.

[wismill]

Rebased

[fendor]

LGTM, thanks!

I have one documentation nitpick, please explain in ignoreProgramAffixes why we are ignoring these prefixes, so that the knowledge isn't lost in the future :)

[ulysses4ever]

@mergify backport 3.12

[mergify]

backport 3.12

✅ Backports have been created

• #10079 Fix --program-suffix resulting in invalid symlink (backport #10056) has been created for branch 3.12 but encountered conflicts