#5878: main-is is too conservative
---------------------------------+------------------------------------------
Reporter: simonpj | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 7.4.1
Keywords: | Os: Unknown/Multiple
Architecture: Unknown/Multiple | Failure: None/Unknown
Difficulty: Unknown | Testcase:
Blockedby: | Blocking:
Related: |
---------------------------------+------------------------------------------
Conrad Parker writes: We have a project with around 200 Haskell source
files, and around 20
executables which import these (as well as importing third-party
libraries). We first build all the non-main files using a makefile
generated with `ghc -M`. We then build the executables using a separate
invocation of "`ghc --make --main-is foo.hs`", for each foo.hs. This
worked fine with ghc-7.2.1; each final "`ghc --make`" would simply link
the pre-built object files -- but with ghc-7.4.1 all these files are
recompiled for each target executable. As a result our full build
takes around '''10-20x longer with ghc-7.4.1 than ghc-7.2.1'''.
Looking at `compiler/iface/FlagChecker.hs`, it seems that the `--main-is`
flag is used as an input to the recompilation checker. It would make
sense that `--main-is` should force recompilation of the particular file
that exports '`main`', but it also forces recompilation of its
dependencies. Is this a bug or is there a good reason to recompile
everything?
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5878>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
_______________________________________________
Glasgow-haskell-bugs mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
