Relax tar upper bound

[ffaf1]

Template Β: This PR does not modify cabal behaviour (documentation, tests, refactoring, etc.)

Close #9556

Include the following checklist in your PR:

• Patches conform to the coding conventions.

[Bodigrim]

@ffaf1 you also need to update bounds in Cabal-tests.cabal, otherwise CI would not pick up tar-0.6.

[ffaf1]

I need help with CI.

<no location info>: error: [-Wunused-packages, -Werror=unused-packages]
    The following packages were specified via -package or -package-id flags,
    but were not needed for compilation:
      - tar-0.6.0.0

I don't really get why it complains about redundant tar, I did not abstract everything behind a .Compat module.

[geekosaur]

Looks to me like it's only used in a test, but you added it to cabal-install?

[geekosaur]

Come to think of it, that can't be right because it is used to read the package index. Which means there's at least one missing change somewhere.

[Bodigrim]

This is likely a bug on GHC side caused by an internal sublibrary, please disable the warning.

[philderbeast]

-Wunused-packages is picky, down to the component level. @ffaf1 I had a look at your branch and think the warning works well except for false positives with ghc <9:

$ git diff
diff --git a/cabal-install/cabal-install.cabal b/cabal-install/cabal-install.cabal
index aca2d67dd..e7f73aaff 100644
--- a/cabal-install/cabal-install.cabal
+++ b/cabal-install/cabal-install.cabal
@@ -42,7 +42,8 @@ common warnings
     ghc-options: -Wall -Wcompat -Wnoncanonical-monad-instances -Wincomplete-uni-patterns -Wincomplete-record-updates
     if impl(ghc < 8.8)
       ghc-options: -Wnoncanonical-monadfail-instances
-    if impl(ghc >=8.10)
+    if impl(ghc >= 9)
+      -- WARNING: Even though introduced with GHC 8.10, this warning gives false positives with GHC 8.10.
       ghc-options: -Wunused-packages
 
 common base-dep

[Bodigrim]

@gbaz is it good to go?

[ffaf1]

@mergify backport

[mergify]

backport

❌ No backport have been created

No destination branches found

[ffaf1]

@mergify backport 3.10

[mergify]

backport 3.10

✅ Backports have been created

• #9596 Relax tar upper bound (backport #9557) has been created for branch 3.10 but encountered conflicts