Feature request: add option to enable dumping of preprocessed source (.i)

[paradogz]

When clang crashes for some reason, the preprocessed source code is needed for bug report. With clang compiler you can get it by using -save-temps option (and also -E). It would be useful if c2ffi had similar option to enable generation of .i/.ii file.

[rpav]

I will look into this. It sounds like something that should be straightforward.

However, if c2ffi is crashing, please file a separate report with the issue! ;)

[paradogz]

Yes, c2fii crashes, but it happens in clang code (it looks like this: http://llvm.org/bugs/show_bug.cgi?id=20608)

[rpav]

Hmm, if this is not reproducible with clang itself, it's very probably still a c2ffi bug ... e.g., a missing header (the most common thing I encounter) leads to a missing type error which would otherwise stop clang, but c2ffi still tries to extract useful information.

I'm digging through the API ref now to see where to pull the preprocessed source, but it may not be straightforward. Also, have you tried 3.5?

[rpav]

Ah, found PrintPreprocessedOutput but I haven't tested to see what you actually get.

[rpav]

Notably, everything in that file is static, and I'm not yet sure how it's called directly. However, that may be unnecessary; Preprocessor::setPreprocessedOutput looks promising, and I'm adding some code now.

[rpav]

All right, I've added this to master, but it's not in the 3.4 branch yet.

[rpav]

This works in the 3.4 branch as well; once 3.5 rebuilds I'll make -o work with -E and pull that to 3.4 as well. I do recommend upgrading to 3.5 though since not much more work is likely to happen in 3.4, especially since 3.6 looks imminent.

[rpav]

All right, d54f597 should complete this feature. hth.

[paradogz]

I used llvm 3.5 for the last tests (but it was crashing the same way). Thank you for implementation of this feature, I should test again the next week

[paradogz]

Ok, I've tried out c2ffi -E and now I'm getting some error output to the console (the same when running clang with equivalent commandline btw) - see https://gist.github.com/paradogz/993c629d640b866cbb00
(the preprocessed source is generated just fine)

Addressing those errors:

1. I guess I have to ask you to add -std=c++11 option :) (can open a separate feature request if needed)
2. Macros. If I try to run with -M, I get that segmentation fault before anything is written to the generated file. What is the format of the generated file? / is it possible to define those macros manually?

[rpav]

See #12. I've also added a --std option, but I'm not sure it'll end up being necessary.

[paradogz]

it could be -std (with single dash) for clang command line compatibility (but thanx anyway!)