Error messages when mixing profiled and unprofiled code

[Alastair Reid]

I just went through an interesting (== painful) remote debugging
session with one of my clients which could be avoided by improving 
an error message.

If you compile a program for profiling but don't have profiling
versions of the standard libraries, then the linker generates reports
like:

  ghc-5.04.1: can't find module `List' (while processing "./../Flattener.hs")

This is utterly baffling since:

1) It is unthinkable that a standard GHC installation would lack 'List'
2) The code compiles fine on other machines (which I later realised
   had the profiling libs installed).

A much better error message would be:

  ghc-5.04.1: can't find profiling version of module `List' (while ...)
                         ^^^^^^^^^^^^^^^^^^^^

I leave it to you whether it would add these extra words only if it
had an ordinary version of List.


--
Alastair Reid                 alastair at reid-consulting-uk.ltd.uk  
Reid Consulting (UK) Limited  http://www.reid-consulting-uk.ltd.uk/alastair/