cabal run --dry-run runs executable if it has been built before

[adamgundry]

Suppose the current project has a foo executable that has been built already (e.g. via cabal v2-build foo). Then cabal v2-run foo --dry-run will re-run dependency solving and display a "the following would be built" message without actually building anything (as expected), but then will run the existing executable.

Is this intended? I would expect cabal v2-run foo --dry-run to behave like cabal v2-build foo --dry-run, i.e. print out the dependencies to be built but not actually run anything. I can't see documentation in the manual for --dry-run, and the --help text says

    --dry-run  Do not install anything, only print what would be installed.

Tested with cabal 3.4 on Linux.

[phadej]

That looks like a bug.

% /opt/cabal/3.2/bin/cabal run initialization --dry-run
Resolving dependencies...
Build profile: -w ghc-8.6.5 -O1
In order, the following would be built (use -v for more details):
 - splitmix-0.1.0.3 (lib) (cannot read state cache)
 - splitmix-0.1.0.3 (test:initialization) (first run)
/code/public-haskell/splitmix/dist-newstyle/build/x86_64-linux/ghc-8.6.5/splitmix-0.1.0.3/t/initialization/build/initialization/initialization: createProcess: runInteractiveProcess: exec: does not exist (No such file or directory)

I.e. it indeed doesn't build, but it runs (and if there's something, it will succeed).

I can imagine the use case for that, but --dry-run is not a flag I'd imagine for that. Also because, cabal test --dry-run doesn't run test suites...

% /opt/cabal/3.2/bin/cabal test initialization --dry-run
Resolving dependencies...
Build profile: -w ghc-8.6.5 -O1
In order, the following would be built (use -v for more details):
 - splitmix-0.1.0.3 (lib) (cannot read state cache)
 - splitmix-0.1.0.3 (test:initialization) (first run)

---

That said, cabal v2-build, cabal v2-run, cabal v2-test with --dry-run would all do the same, so if v2-build works, use that for now.

[fgaz]

Closing in favor of the bigger #7379. PRs still welcome :)