Segmentation fault when .prof file not writeable

To reproduce:

$ echo 'main = return ()' > Test.hs

$ touch Test.prof

$ chmod -w Test.prof

$ ghc -prof Test.hs
[1 of 1] Compiling Main             ( Test.hs, Test.o )
Linking Test ...

$ ./Test +RTS -hr{} -hc
Can't open profiling report file Test.prof
Segmentation fault (core dumped)

The warning is ok (maybe it should be an error?), but it shouldn't segfault.

Running ./Test +RTS -hr works fine.

http://downloads.haskell.org/~ghc/master/users-guide/profiling.html#rts-options-for-heap-profiling:

• -hc: Breaks down the graph by the cost-centre stack which produced the data.
• -hr⟨cc⟩: Restrict the profile to closures with retainer sets containing cost-centre stacks with one of the specified cost centres at the top.

Bug exists since dbef766c (2002):

- you can now restrict a heap profile to certain retainer sets,
  but still display by cost centre (or type, or closure or
  whatever).

Because it didn't update this code+comment introduced in db61851c (2001):

// The following line was added by Sung; retainer/LDV profiling may need
// two output files, i.e., <program>.prof/hp.
if (RtsFlags.ProfFlags.doHeapProfile == HEAP_BY_RETAINER)
    RtsFlags.ProfFlags.doHeapProfile = 0;

Another relevant commit a4e17de6:

Author: simonmar <unknown>
Date:   Wed Nov 28 15:42:26 2001 +0000

    [project @ 2001-11-28 15:42:26 by simonmar]
    Don't need the .prof file when LDV-profiling.

Trac metadata

Trac field	Value
Version	7.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	low
Resolution	Unresolved
Component	Profiling
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

mentioned in issue #7149 (closed)

changed weight to 3

added Tbug Trac import profiling labels

changed milestone to %8.0.1

assigned to @trac-thomie

Trac metadata

Trac field	Value
Differential revisions	- → D1849

Trac metadata

Trac field	Value
Related	- → #7149 (closed)

mentioned in commit 6d2bdfd8

Might as well merge this, although I don't think anyone will run into it soon.

added 1 deleted label

closed

Merged as 8efe964a.

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedFixed

removed 1 deleted label

mentioned in issue #14706 (closed)

added Plow label