#16253: Offer a shorthand for `--skip=_build/stage$n/compiler/.dependencies.mk` -------------------------------------+------------------------------------- Reporter: sgraf | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Build System | Version: 8.6.3 (Hadrian) | Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by snowleopard): Looking at the documentation of `ghc -M`, it looks like the current per- package approach is due to a limitation of GHC's dependency analysis. Quoting from https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/separate_com... #makefile-dependencies
In general, `ghc -M Foo` does the following. For each module `M` in the set `Foo` plus all its imports (transitively), it adds to the Makefile [...]
That is, GHC always does **transitive** dependency analysis, which means invoking it separately on each file would be rather inefficient (each time it will likely traverse almost the whole dependency graph). This is why Make and Hadrian choose to perform the analysis just once but for the whole package. Perhaps, it's not too difficult to add a more fine-grain dependency analysis to GHC, i.e. produce only the list of immediate dependencies of a specified module. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16253#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler