Though actually that might not help for the kernel headers because I think they do not declare the regparam calling convention and just rely on gcc flags when compiling.
You are correct - the call convention has to be declared manually. There is no reasonable way for c2hs to learn it.
Do you have any suggestion for that? The information would have to be supplied somehow. I guess as command line parameters to c2hs. I guess we just need to mirror gcc in that respect, to accept some of the gcc flags that globally modify the ABI.
c2hs --gcc-abi-mode=-fregparam=3
This is exactly what I would suggest.
Of course it also needs ghc to support that FFI calling convention, which I understand you've made as a local ghc modification.
The same applies to stdcall vs ccall however, so it's generally useful even if you never contribute the regparam calling convention.
True. Perhaps I'll try pushing the regparm3 patch to HEAD. The main issue is flexibility - it would be much better to support some sort of __attribute__() system so we don't have to manually ad regparmX for all reasonable values of X.
In the end the solution I have is to manually write the above C section and the foreign import call using a regparm3 calling convention. This isn't to say c2hs isn't used - its still hugely helpful (so long as the headers remain easy to convert to ANSI C), but just my quick experience.
BTW, what do you mean about ANSI C?
I meant there exists at least one aspect (perhaps a bug) to the kernel headers that cause an error when c2hs tries to parse the headers. In the FC11 2.6.30 headers they use an enum when declaring an extern function prototype - without declaring the enum (timers.h). The solution is to #include
, which contains the enum declaration. Ah, and gcc accepts this without warning?
Yes
Perhaps you can boil down a test case and submit it. I tried hard when making the C parser to cover all the GNU extensions and I ran it over all the kernel sources for some older kernel release. So it's worth fixing these things to maintain its usability.
I just made this and gcc accepts it without issue: ---- START enum.h ---- extern enum hello hello_fn(int); ---- END enum.h ---- This can be # included in any .c and gcc will compile it without complaint (even with -Wall). OTOH, c2hs will not parse such a file. Thomas