Windows interface for clang

I’ve finally developed what I think is a general solution to the problem of building existing Windows programs with clang:

https://github.com/russellw/wic

Using this, I’ve managed to run attempted builds of Python, Ruby and Perl.

Python 2.7 works - it generates a python.exe that at least passes a preliminary smoke test.

Perl generates an executable that crashes partway through the build. I’ll try to narrow it down further.

Ruby fails with an error message at the configuration step. I’m trying to find out why; it might be something easily fixable.

This seems more relevant to cfe-dev.

I’ve finally developed what I think is a general solution to the problem of building existing Windows programs with clang:

https://github.com/russellw/wic

You seem to be struggling with the need to name the binary ‘cl.exe’. Last time I checked, we installed clang-cl.exe under that name in a specialized director specifically so you can use build systems relying on that name.

-Chandler

This seems more relevant to cfe-dev.

Okay.

You seem to be struggling with the need to name the binary 'cl.exe'. Last
time I checked, we installed clang-cl.exe under that name in a specialized
director specifically so you can use build systems relying on that name.

Right, but:

1. The existence of a binary named cl.exe isn't enough; depending on the
circumstances, the build system may look specifically in the visual studio
directory. Of course, you could do the rename/copy by hand, but it's better
to have it automated, particularly since in practice there is a need to
switch back and forth.

2. Python at least needs to have it switchable specifically for 32-bit or
64-bit builds.

3. wic also supplies the option -Wno-invalid-token-paste which is necessary
for compatibility with the Microsoft preprocessor. I intend adding other
options as needed.

4. Hopefully can also substitute calls to the llvm linke when that's ready
for prime time.

This seems more relevant to cfe-dev.

Okay.

You seem to be struggling with the need to name the binary 'cl.exe'. Last
time I checked, we installed clang-cl.exe under that name in a specialized
director specifically so you can use build systems relying on that name.

Right, but:

1. The existence of a binary named cl.exe isn't enough; depending on the
circumstances, the build system may look specifically in the visual studio
directory. Of course, you could do the rename/copy by hand, but it's better
to have it automated, particularly since in practice there is a need to
switch back and forth.

For MSBuild, you can pass along /p:PlatformToolset=LLVM-vs2013 (or edit the
project file for the same effect) to bypass this. I know Python's build is
based on VS projects, so I would've expected this to work there. I wouldn't
know about Ruby or other builds, and I imagine swapping the binary is
useful for particularly inflexible systems.

2. Python at least needs to have it switchable specifically for 32-bit or

64-bit builds.

3. wic also supplies the option -Wno-invalid-token-paste which is
necessary for compatibility with the Microsoft preprocessor. I intend
adding other options as needed.

Was the issue here in user code or a system header? If the invalid token
paste came from a system header, we shouldn't have errored. If it's in user
code, it's up to them to decide if they want to suppress the issue by
adding the flag themselves or fix it for conformance.

Different users have different needs, so it's not clear where the default
level of conformance diagnostics vs. compatibility should be. I guess we
should probably downgrade this to a -Wmicrosoft warning or something when
MS compatibility is on.

For MSBuild, you can pass along /p:PlatformToolset=LLVM-vs2013 (or edit

the project file for the same effect) to bypass this. I know Python's build
is based on VS projects, so I would've expected this to work there. I
wouldn't know about Ruby or other builds, and I imagine swapping the binary
is useful for particularly inflexible systems.

Right, as you say, msbuild is relatively flexible and Python uses it, so
you would expect such techniques to work there, but unfortunately they
don't - I didn't use that particular flag, but I used similar ones that
allow pointing msbuild at a different compiler and it failed because
regardless of whether you select a 32 or 64 bit build, Python for some
reason requires some object file to be compiled 32-bit and some other one
to be compiled 64-bit.

Was the issue here in user code or a system header? If the invalid token

paste came from a system header, we shouldn't have errored. If it's in user
code, it's up to them to decide if they want to suppress the issue by
adding the flag themselves or fix it for conformance.

User code, Python again. Mind you, I'm not disagreeing with you about the
scenario where one is writing new code with a view to making sure it works
with clang from the start. It's just that I'm dealing with the trickier
scenario where one is trying to compile a large quantity of code that has
already been written by other people without regard to clang.

Different users have different needs, so it's not clear where the default
level of conformance diagnostics vs. compatibility should be. I guess we
should probably downgrade this to a -Wmicrosoft warning or something when
MS compatibility is on.

I think so, yes. Greenfield projects can easily add flags for tighter
conformance checking if so desired.