Heap profiling restricted with retainers (+RTS -hrfoo -hc) segfaults

[akio]

Steps to reproduce:

% cat hello.hs
main = print $ last [0..]
% ghc hello.hs -prof
[1 of 1] Compiling Main             ( hello.hs, hello.o )
Linking hello ...
% ./hello +RTS -hrfoo -hc
zsh: segmentation fault  ./hello +RTS -hrfoo -hc

[akio]

A proposed patch

[akio]

The issue seems to be that the retainer profiling code tries to write to a NULL file pointer.

[pcapriotti]

Applied, thanks.

commit 4e0a957758af94bc39ff51814bad54faf96a94b9
Author: Takano Akio <aljee@hyper.cx>
Date:   Wed Aug 15 11:16:40 2012 +0900

    Profiling: open .prof when -hr<cc> is specified
    
    The code for retainer profiling is used with e.g. +RTS -hc -hrfoo -RTS,
    as well as with +RTS -hr -RTS.

[pcapriotti]

Merged as 66cb7e7293709d573c0d5e320507214e64127fde.