Make "missing custom-setup stanza" warnings less noisy

[sjakobi]

These were introduced in #3019. Here's a snippet from a build log:

comonad-5: configure
Package comonad uses a custom Cabal build, but does not use a custom-setup stanza
Not using the explicit setup deps approach based on configuration
Strongly recommend fixing the package's cabal file
comonad-5: build
Package comonad uses a custom Cabal build, but does not use a custom-setup stanza
Not using the explicit setup deps approach based on configuration
Strongly recommend fixing the package's cabal file
comonad-5: copy/register
Package comonad uses a custom Cabal build, but does not use a custom-setup stanza
Not using the explicit setup deps approach based on configuration
Strongly recommend fixing the package's cabal file
Package comonad uses a custom Cabal build, but does not use a custom-setup stanza
Not using the explicit setup deps approach based on configuration
Strongly recommend fixing the package's cabal file
bifunctors-5.4.1: configure
bifunctors-5.4.1: build
bifunctors-5.4.1: copy/register
profunctors-5.2: configure
profunctors-5.2: build
semigroupoids-5.1: configure
Package semigroupoids uses a custom Cabal build, but does not use a custom-setup stanza
Not using the explicit setup deps approach based on configuration
Strongly recommend fixing the package's cabal file
semigroupoids-5.1: build
Package semigroupoids uses a custom Cabal build, but does not use a custom-setup stanza
Not using the explicit setup deps approach based on configuration
Strongly recommend fixing the package's cabal file
profunctors-5.2: copy/register
semigroupoids-5.1: copy/register
Package semigroupoids uses a custom Cabal build, but does not use a custom-setup stanza
Not using the explicit setup deps approach based on configuration
Strongly recommend fixing the package's cabal file
Package semigroupoids uses a custom Cabal build, but does not use a custom-setup stanza
Not using the explicit setup deps approach based on configuration
Strongly recommend fixing the package's cabal file

1. There should only one warning per package.
2. I think these warnings should only be shown for local packages.
3. Maybe they could link to relevant documentation for custom-setup?

[mgsloan]

Fixed! I agree that it makes sense to only warn for local packages.

This will also improve build performance for packages with custom setup, the multiple messages were from multiple builds of custom setup :o

Maybe they could link to relevant documentation for custom-setup?

Not sure what would be a good thing to link to, so I didn't do this.

[sjakobi]

Thanks a lot @mgsloan!

[ekmett]

These warnings aren't going away on my end until we can depend universally on a version of cabal that supports custom setup and drop support for old cabal versions. At present much of my code works back to ghc 7.0 or 7.2, which typically ships with a much older cabal.

[mgsloan]

@ekmettIn Due to the changes described here, with the next version of stack, at least users of your packages won't get the warnings.

That is a good point, though, you can't make the warning go away and retain backwards compatibility.

[ekmett]

Happy to hear!