-fhpc assumes original sources relative to the current directory
For the most part, ghc can be invoked in a manner that is independent of the current directory by suitable use of -i
options.
With -fhpc
it appears that the hpc bits always look in the current directory to find original source files.
Consider the following file layout:
Codec/Compression/Zlib/Stream.hsc
dist/build/Codec/Compression/Zlib/Stream.hs
examples/gunzip.hs
Now if we cd
to examples
and run:
ghc --make gunzip.hs -lz -i../ -i../dist/build
then it works fine. It finds Codec/Compression/Zlib/Stream.hs
in ../dist/build
and it never bothers to look for the original source of course.
Now in -fhpc
mode it has to also find the original sources so that it can match things back to them. However just adding -fhpc to the above command fails:
ghc --make gunzip.hs -lz -i../ -i../dist/build -fhpc
[1 of 4] Compiling Codec.Compression.Zlib.Stream ( ../dist/build/Codec/Compression/Zlib/Stream.hs, ../dist/build/Codec/Compression/Zlib/Stream.o )
Codec/Compression/Zlib/Stream.hsc: getModificationTime: does not exist (No such file or directory)
So it's clearly not looking in the directory given by -i..
for the original sources. Also, the failure mode is a bit unfriendly.
Cabal sometimes takes advantage of the fact that ghc can be invoked in a manner that is independent of the current directory, and we would like to add hpc support into Cabal.
Trac metadata
Trac field | Value |
---|---|
Version | 6.10.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |