I'm now ready to "make". I have set up a mk/build.mk with the just following line:

prefix = /home/djs25/testghc

I should then be able to invoke my test ghc as

/home/djs25/testghc/ghc-5.02.2/bin/ghc

I have some questions:

1. How does ghc know where to get its libraries from? Will it pick them up from

/home/djs25/testghc/ghc-5.02.2/bin/ghc

or

/usr/lib/ghc-5.02.2

If you invoke fptools/ghc/compiler/ghc, then it looks for libraries in $(prefix)/lib/ghc-$(version). If you instead invoke fptools/ghc/compiler/ghc-inplace, then it looks for libraries in the source tree (we call this the "in-place" compiler).

2. What do I put in build.mk to change the version? I would like

/home/djs25/testghc/ghc-5.02.2/bin/ghc --version

to give

The Glorious Glasgow Haskell Compilation System, version 5.02.2test

so that I know am picking up my test version rather than the real thing.

You can fiddle with the version in fptools/ghc/mk/version.mk, but I can't guarantee that if you don't use a version of the form A.BB.C or A.BB.<date>, then things will work properly. eg. configure scripts which look for GHC will attempt to parse the version number and fail if it isn't in a recognised form. Cheers, Simon