REPL command in project requires a target by philderbeast · Pull Request #10684 · haskell/cabal

philderbeast · 2024-12-28T13:20:47Z

Fixes #10527 and #9983. Depend-on: #10688.

Doesn't allow an empty list of targets with a project context.

With a project, the REPL command requires a target. If one is not given then a message is shown explaining this and naming the project if the --project-file option was given (but not when the default 'cabal.project' project name is used implicitly). ~~We're not yet able to list project targets so in the meantime, the messages lists the packages of the project.~~

When the implicit default cabal.project is used:

$ cat cabal.project
packages: pkg-one pkg-two

$ cabal repl
Error: [Cabal-7076]
With a project, the REPL command requires a single target. The packages in this
project are:
 - pkg-one
 - pkg-two

When the --project-file option is used, the file name is included:

$ cat some.project 
packages: pkg-one pkg-two

$ cabal repl --project-file=some.project
...
Error: [Cabal-7076]
With a project, the REPL command requires a single target. The packages in this
project, 'some.project', are:
 - pkg-one
 - pkg-two

When the project has no packages, this is mentioned in the message:

$ cat empty.project

$ cabal repl --project-file=empty.project
...
Error: [Cabal-7076]
There are no packages in 'empty.project'. Please add a package to the project and pick a
single [package:][ctype:]component as target for the REPL command.

Before the fix the message mentioned a fake-package-0. This was confusing:

$ ~/.ghcup/bin/cabal-3.12.1.0 repl --project-file=some.project
...
Error: [Cabal-7076]
Internal error when trying to open a repl for the package fake-package-0. The
package is not in the set of available targets for the project plan, which would
suggest an inconsistency between readTargetSelectors and resolveTargets.

Earlier cabal-install:exe:cabal versions mentioned using all as the target but this won't work for the REPL command:

$ ~/.ghcup/bin/cabal-3.10.3.0 repl --project-file=some.project
Error: cabal-3.10.3.0: No targets given and there is no package in the current
directory. Use the target 'all' for all packages in the project or specify
packages or components by name or location. See 'cabal build --help' for more
details on target options.

Patches conform to the coding conventions.
Any changes that could be relevant to users have been recorded in the changelog.
- Is the change significant? If so, remember to add significance: significant in the changelog file.
The documentation has been updated, if necessary.
Manual QA notes have been included.
Tests have been added.

philderbeast · 2025-06-16T20:04:19Z

This pull request will be easier to review once the cfgVerbosity changes are merged.

geekosaur

Approving despite suggestions because they're not functional changes.

cabal-install/src/Distribution/Client/CmdRepl.hs

changelog.d/pr-10684.md

cabal-install/src/Distribution/Client/CmdRepl.hs

ulysses4ever

Thanks for this patch and the test! I have a couple questions...

@mpickering could you take a brief look at this (it's a small patch)? Especially my comment under the -- NOTE:.

changelog.d/pr-10684.md

cabal-install/src/Distribution/Client/CmdRepl.hs

ulysses4ever · 2025-06-18T17:47:44Z

cabal-install/src/Distribution/Client/CmdRepl.hs

+                    text "There are no packages in"
+                      <+> (project <> char '.')
+                      <+> text "Please add a package to the project and pick a component to use as the target of the REPL command."


the no-packages case is certainly already handled in other places today, right? (people keep forgetting packages:... and get an error message.) Is it possible to not duplicate this logic?

After removing the target string manipulation, the current behaviour (#9983) is bad and doesn't cover this case:

$ ~/.ghcup/bin/cabal --numeric-version 3.14.2.0 $ ~/.ghcup/bin/cabal repl --project-dir=cabal-testsuite/PackageTests/ReplProjectTarget --project-file=empty.project Configuration is affected by the following files: - empty.project Warning: There are no packages or optional-packages in the project Resolving dependencies... Error: [Cabal-7076] Internal error when trying to open a repl for the package fake-package-0. The package is not in the set of available targets for the project plan, which would suggest an inconsistency between readTargetSelectors and resolveTargets.

Also I'd be curious to know how to get better output from a debug build of cabal-install with assertions enabled because that version gives me a poorer error report with no line number:

$ cabal repl --project-dir=cabal-testsuite/PackageTests/ReplProjectTarget --project-file=empty.project Warning: this is a debug build of cabal-install with assertions enabled. Configuration is affected by the following files: - empty.project Warning: There are no packages or optional-packages in the project Resolving dependencies... Assertion failed

Warning: There are no packages or optional-packages in the project

is a different issue, I think, (#8679 probably) so it may be wise to try to avoid solving it here.

assertion failure is bad but also looks like a future work. We're minutes from cutting the 3.16 branch and all backporting will have to go through extra careful consideration (mostly deciding the tradeoff: scarse resource for the release vs profit from performing the backport)

The assertion bothers me. I could cut back on the scope of this pull request or dig in more about the assertion.

the no-packages case is certainly already handled in other places today, right? (people keep forgetting packages:... and get an error message.) Is it possible to not duplicate this logic?

@ulysses4ever, it is handled elsewhere but as a warning:

cabal/cabal-install/src/Distribution/Client/ProjectOrchestration.hs

Lines 312 to 314 in 27593dc

-- https://github.com/haskell/cabal/issues/6013

when (null (projectPackages projectConfig) && null (projectPackagesOptional projectConfig)) $

warn verbosity "There are no packages or optional-packages in the project"

So in the meantime (as I'm not suppressing the warning) we get both a warning and an error:

$ cabal repl --project-file=empty.project Warning: this is a debug build of cabal-install with assertions enabled. Warning: There are no packages or optional-packages in the project Error: [Cabal-7076] There are no packages in 'empty.project'. Please add a package to the project and pick a single [package:][ctype:]component as target for the REPL command.

Given the warning (unless there's already some way to suppress it, shouldn't the error message change to be a follow-on to it?

I'm OK with the warning and then the error. Scolding, I warned you and now look what has happened, an error!

I feel the better way to fix this would be to suppress the warning.

ulysses4ever · 2026-01-12T00:45:36Z

Is this not superceded by #11237?

philderbeast · 2026-01-12T13:38:39Z

Is this not superceded by #11237?

Not totally, we can pick a default but don't when there is one package in a project, #11237 (comment).

philderbeast · 2026-01-19T20:43:05Z

I'll need to raise another pull request for the remaining changes, won't I, if only to avoid a conflict with the changelog entry, in changelog.d/pr-10684.md deleted in 8656465?

Most of the changes of this pull request were added with a changelog entry referring to pr-10684 in #11237.

- Show packages when no --project-file is given - Handle the case with no packages in the project - Add a changelog - Add tests - Satisfy hlint - Satisfy fourmolu - Don't need a target when there is one package - Adjust target strings for sole package - Add alt.project tests for ReplOptions - Silence the 1st withCtx call's verbosity - Don't repeat configuration is affected by - Satisfy whitespace - Fixups after rebase - Remove punct variable - Review comment changes - Comma with but joining indep' clauses - Use single package - Update tests, adding more assertions - Improve test descriptions - Mention [package:][ctype:]component - Don't repeat [package:][ctype:]component - Lift validatedTargets, rename r as replFlags - Don't use -XRecordWildCards for configFlags - Add a one.project one pkg test - Remove target string manipulation - Make reportProjectNoTarget a function - Redo ReplProjectTarget tests - Redo ReplProjectNoneTarget tests - Satisfy fix-whitespace - Error whether or not project has packages - Guard against triggering an assertion if targets are null - Skip if Windows - Repl commands mentioning the fake-package - Don't yet automatically pick only choice - Autopick the one package - Split ReplProjectTarget test - Add tests for repl all target - Default target to all with multireplh - Add a retargetting message - Add test for default "all" target when multirepl - Add type synonym TargetPick - Add targetedRepl - RejectNoTargets if target strings not null Co-Authored-By: brandon s allbery kf8nh <[email protected]>

- Update expected fake-package-0 message

philderbeast · 2026-01-21T15:42:55Z

Closing in favour of #11452.

mergify · 2026-01-21T15:43:03Z

⚠️ The sha of the head commit of this PR conflicts with #11452. Mergify cannot evaluate rules on this PR. ⚠️

philderbeast · 2026-01-21T16:03:14Z

⚠️ The sha of the head commit of this PR conflicts with #11452. Mergify cannot evaluate rules on this PR. ⚠️

@geekosaur sorry to have done that to mergify.

geekosaur · 2026-01-21T17:00:05Z

Mergify's too dumb to realize that the PR is closed so it doesn't matter.

mergify · 2026-01-23T15:20:13Z

⚠️ The sha of the head commit of this PR conflicts with #11452. Mergify cannot evaluate rules on this PR. ⚠️

philderbeast marked this pull request as draft December 28, 2024 13:20

philderbeast force-pushed the fix/repl-project-null-target branch 4 times, most recently from 09fcf06 to 6dd178f Compare December 28, 2024 16:31

philderbeast marked this pull request as ready for review December 28, 2024 16:31

philderbeast added attention: needs-review cabal-install: cmd/repl labels Dec 28, 2024

philderbeast marked this pull request as draft December 28, 2024 19:48

philderbeast removed the attention: needs-review label Dec 28, 2024

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philderbeast force-pushed the fix/repl-project-null-target branch 2 times, most recently from 35477a0 to 1b8edc1 Compare January 12, 2025 12:37

philderbeast force-pushed the fix/repl-project-null-target branch from 1b8edc1 to 2a587e3 Compare March 22, 2025 20:31

philderbeast force-pushed the fix/repl-project-null-target branch from 2a587e3 to 59869f3 Compare April 19, 2025 12:42

philderbeast force-pushed the fix/repl-project-null-target branch from 59869f3 to d34ecf2 Compare June 16, 2025 19:24

philderbeast mentioned this pull request Jun 16, 2025

Add cfgVerbosity #10688

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philderbeast force-pushed the fix/repl-project-null-target branch from d34ecf2 to 80875e2 Compare June 16, 2025 19:52

philderbeast mentioned this pull request Jun 16, 2025

make cabal less chatty w.r.t. project files in use #10940

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philderbeast marked this pull request as ready for review June 16, 2025 20:01

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geekosaur approved these changes Jun 16, 2025

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ulysses4ever reviewed Jun 18, 2025

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philderbeast marked this pull request as draft January 11, 2026 21:28

philderbeast force-pushed the fix/repl-project-null-target branch 2 times, most recently from 0835a09 to 9efb34b Compare January 11, 2026 22:28

ulysses4ever removed a link to an issue Jan 15, 2026

cabal repl (more or less) silently fails since 3.16.0.0 #11107

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philderbeast force-pushed the fix/repl-project-null-target branch 12 times, most recently from 2216929 to 84a58e9 Compare January 18, 2026 14:54

philderbeast and others added 5 commits January 21, 2026 09:44

Unfail REPL tests with default targets

8578f30

- Update expected fake-package-0 message

Guard against infinite retargeting & null pkgs

b9a1cda

Redo the changelog.

845d421

Remove TargetPick type synonym

d56b579

philderbeast mentioned this pull request Jan 21, 2026

Default package name and all targets for REPL #11452

Merged

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	-- https://github.com/haskell/cabal/issues/6013
	when (null (projectPackages projectConfig) && null (projectPackagesOptional projectConfig)) $
	warn verbosity "There are no packages or optional-packages in the project"

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