build system

Reid Barton rwbarton at
Tue Jul 21 21:16:23 UTC 2015

On Tue, Jul 21, 2015 at 4:21 PM, Simon Peyton Jones <simonpj at>

>  Friends
> With the new build system I get this kind of output
>   HC [stage 1] compiler/stage2/build/SPARC/AddrMode.o
>   HC [stage 1] compiler/stage2/build/CmmContFlowOpt.o
>   HC [stage 1] compiler/stage2/build/CmmImplementSwitchPlans.o
>   AR
> libraries/Cabal/Cabal/dist-install/build/libHSCabal-
> C:\fp\HP-2014-\mingw\bin\ar.exe: creating
> libraries/Cabal/Cabal/dist-install/build/libHSCabal-
>   LD
> libraries/Cabal/Cabal/dist-install/build/HSCabal-
>   HC [stage 1] utils/ghc-cabal/dist-install/build/Main.o
> *WARNING*: file compiler\specialise\Specialise.hs, line 724
I assume this is when you run validate?

>  But I have no idea which module caused the WARNING, nor do I have a
> command-line to copy/paste to reproduce it.  (With the old module-at-a-time
> system I could copy/paste the command line for the specific module.)
> Is there a way to
> ·        make things sequential so I can tell which warnings from which
> module
make -j1, which is make's default, but validate invokes make with -j2 or
higher (depending on how many CPUs it thinks your system has).

> ·        get a command line to copy/paste to compile that module?
validate sets the GHC build system variable V=0 in mk/
You can override it from the make command line with make V=1.

So, you can run "make V=1" to restart the build serially and with the
command to build each file displayed. Note that serial make may build
modules in a different order than parallel make, so it may take a while for
make to get around to building the module that failed.

Reid Barton
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