Add '--repl-no-load' option to skip module load in REPL

[sirlensalot]

Fixes #7541

Notes/review items:

• not supported in GHCJS repl
• The docs for the existing repl flags, "use this option for the repl", should maybe be improved?

• 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.

Manually tested on library and executable repl loads. EDIT tests added.

[emilypi]

@sirlensalot can you add docs for this please?

[fendor]

A test-case that proves the feature working would be great!

[sirlensalot]

@sirlensalot can you add docs for this please?

@emilypi I assume this means add docs to cabal-commands.rst; there are minor/incomplete mentions of the repl elsewhere.

Why does cabal-commands.rst only document v2-repl (and for that matter v2-everything)? Is that supposed to be the "true" command doc? I ask b/c I've been confused by this before and been reluctant to read "v2" docs. Likewise, this change is not just for v2-repl so it's even more confusing.

[fendor]

@sirlensalot v2- commands are the normal, modern commands that you usually use when you use cabal (with a version > 3.0).

E.g. cabal repl is a synonym for cabal v2-repl, they do exactly the same. As such, you did modify the v2-replcommand, when you changed CmdRepl.hs. As a rule of thumb, all modules that start with Cmd*.hs, are v2- commands, or modern versions of their sibling module (e.g. Repl.hs). How can you know? Basically no chance, the final name of the commands on the command line are determined by the argument parsing (I think that happens in Simple.hs but don't quote me on that).

Why do we have both v2-, v1- and un-prefixed commands? v1- are very old and basically deprecated for the normal user, v2- are the new commands which you usually use. And the un-prefixed version are just a default that switched in cabal version 3.0. We have both since cabal changed significantly, a number of breaking changes, and this way, people can keep using v1- commands if they really need to.

[sirlensalot]

A test-case that proves the feature working would be great!

@fendor a breadcrumb of where this test should go would be great. There's tests in cabal-install, Cabal-testsuite, Cabal-test. I was working with the first as IntegrationTests2 seemed like a good fit.

[fendor]

@sirlensalot It might be a bit complicated, indeed... I'll look into it and report tomorrow what I think is the best place to add tests.

[sirlensalot]

@sirlensalot It might be a bit complicated, indeed... I'll look into it and report tomorrow what I think is the best place to add tests.

@fendor I think I found a good starting place in cabal-testsuite, https://github.com/haskell/cabal/blob/ea830d70144db14175d20f139973aa2865337def/cabal-testsuite/PackageTests/ReplCSources/cabal.test.hs

IntegrationTests2 while familiar/unit-testy doesn't have the infra to work with STDIN so it just hangs.

[sirlensalot]

Tests, docs added; changelog updated.

[fendor]

LGTM!

[emilypi]

@Mergifyio backport 3.6

[mergify]

Command backport 3.6: success

Backports have been created

• #7593 Add '--repl-no-load' option to skip module load in REPL (backport #7578) has been created for branch 3.6