[ fix #7251 ] sort and nub module list inferred by cabal init --lib

[andreasabel]

[ fix #7251 ] sort and nub module list inferred by cabal init --lib

This should fix the problem that duplicate entries end up in exposed-modules, e.g. from Foo.x and Foo.hs (with alex as build-tool).

• > Patches conform to the coding conventions.
• > Any changes that could be relevant to users have been recorded in the changelog (add file to changelog.d directory).
  This fixes a broken behavior, shouldn't need mentioning.
• > The documentation has been updated, if necessary.
  Ditto

Please also shortly describe how you tested your change. Bonus points for added tests!

Couldn't test yet because of #7251 (comment) :-(

TODO:

• test
• changelog

[andreasabel]

Here is a test script now (using BNFC):

bnfc --version || cabal install BNFC
mkdir -p myparser
cd myparser
echo "Foo. Bar ::= Integer" > Foo.cf
bnfc -o src -d -m Foo.cf
make -C src
mv src/Foo/Test.hs Main.hs
cabal init --libandexe --application-dir=.
cabal build all
cat myparser.cabal

This will create a meaningful myparser.cabal except that the executable section does not have the necessary dependency on the library.

[fgaz]

Having a test for this in cabal-testsuite would be good

[fgaz]

This fixes a broken behavior, shouldn't need mentioning.

Bug fixes go in the changelog too, plus there's the sorting

Here's how the changelog.d works: https://github.com/haskell/cabal/blob/master/CONTRIBUTING.md#changelog

[andreasabel]

Thanks for the feedback @fgaz!

• Could you point me to a location where the new test should reside?
• Is there maybe some documentation how to add a test?

[fgaz]

The most straightforward way to test this is with a package test. You can add it in cabal-testsuite/PackageTests, where you can also find a readme and many examples. Check out the "Hermetic tests" section in particular, since you'll need it for this test

[fgaz]

@emilypi does #7344 supersede this?

[emilypi]

@fgaz yeah. We've fixed this in the omnibus.