#7027: Lots of unnecessary recompilation
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Reporter: selinger | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.4.2 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: None/Unknown | Testcase:
Blockedby: | Blocking:
Related: |
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The release notes for 7.4 state:
"The recompilation checker now takes into account what flags were used
when compiling. For example, if you first run ghc -c Foo.hs, and then ghc
-DBAR -c Foo.hs, then GHC will now recompile Foo.hs."
This has some undesired side effects. For example, I have a project with
over 100 source files. Sometimes I like to try a different main function
with -main-is, just for testing. This worked fine with 7.2, but ghc 7.4,
in this situation, recompiles the whole world - including the 99 source
files that are unaffected by this option.
Since this new behavior involves a - sometimes substantial - tradeoff
between safety and efficiency, can there please be a command line option
to turn it off? At least until someone figures out a way to do it smartly.
To reproduce: recompile any already compiled multi-module program with
-main-is.
Thanks, -- Peter
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7027>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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