peekCString crashes on handling nullPtr

Not quite sure what the 'correct' behaviour here is; but here's a minimal test case:

-bash-3.2$ more TestCase.hs
import Foreign
import Foreign.C

main = do
    str <- peekCString nullPtr
    putStrLn str

-bash-3.2$ ghc --make TestCase.hs 
-bash-3.2$ ./TestCase 
Segmentation fault

I was not expecting a seg fault here. At minimum, peekCString documentation should describe what is meant to happen when you pass it a nullPtr (currently not mentioned at all). Better would be some form of error reporting - I'm integrating with a C library, and it took me a while to track down what the root cause of the seg fault was.

Trac metadata

Trac field	Value
Version	6.12.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (FFI)
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