ghc has a stack space leak when prints warnings

Found on a crash when ghc tried to print a warning in a huge assembly file.

I've simplified it to autogenerated C file with an error:

# generate 10 million lines file
# and put an error into the very end of file
$ { for i in `seq 1 $((10 * 1000 * 1000))`; do echo "// a comment number $i"; done; echo 'static int foo = ;'; } > a.c

$ LANG=C powerpc64le-unknown-linux-gnu-ghc -c a.c +RTS -K128M

stack overflow: use +RTS -K<size> to increase it

C compiler tried to output something like the following to stderr:

a.c:10000001:0: error:
     error: expected expression before ';' token
     static int foo = ;

GHC finds 'a.c:10000001' location and tries to pretty-print the line. We get a space leak somewhere.

Trac metadata

Trac field	Value
Version	8.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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