provide an MSVC-compatible command line interface, similar to zig cc but with MSVC-flavored flags

[andrewrk]

clang already has a "cl mode", and it should be pretty minimal efforts to also support zig cl, given the framework we already have in place for zig cc. Thanks to ihnorton for the idea.

[adontz]

https://clang.llvm.org/docs/MSVCCompatibility.html

I think "drop in replacement" means no compatibility issues, while what CLang tries to achieve is ability to compile Windows SDK headers. I think "ability to compile latest Windows SDK headers" is what the real goal should be, not "drop in replacement", this is simply not a realistic task. MSVC has a lot of language extensions.

[jagt]

Hi!

Does this mean that zig c++ is broken on windows for now?
I've tried a bit that zig cc works and zig c++ seems to error out on Windows with VS2017.

[andrewrk]

On Windows you might want to use -target native-native-gnu so that Zig is not required to integrate with MSVC.

[jagt]

Thanks for the reply.

-target native-native-gnu indeed works. But seems it can compile fine but fails to link a executable.
See example below:

zig cc -o hello_c.exe hello_c.c # works
zig c++ -target native-native-gnu -c foo.cc # works
zig -target native-native-gnu c++ -o hello_cpp.exe hello_cpp.cc  # process won't terminate

I'm runnning zig 0.6.0 on windows.
I think I'll wait a bit for zig cl to work.

[andrewrk]

process won't terminate

It will. Give it a minute while it builds and caches mingw-w64. The terminal progress indicator isn't implemented for Windows terminals yet. It only has to do this the first time.

[jagt]

Yes it indeed work. Might need to print something atleast to stderr so it's less confusing.
I'll play with it a bit. Thanks a lot for your good work!

[andrewrk]

There is a whole progress bar system in place, but it does not yet know how to display on windows terminals. Contribution welcome!

zig/lib/std/progress.zig

Line 102 in 48dc3b6

self.terminal = if (stderr.supportsAnsiEscapeCodes()) stderr else null;

[andrewrk]

@LemonBoy implemented progress for Windows terminals just now in #5133, merged in 173a143.

[GavinRay97]

Is there still interest in this?

I'm unfamiliar with Zig source (and C/C++ in general), but if Clang is in-tree, maybe this could be used?

llvm::opt::DerivedArgList* MSVCToolChain::TranslateArgs(const llvm::opt::DerivedArgList &Args,
                             							StringRef BoundArch,
                             							Action::OffloadKind OFK) {}

https://github.com/llvm/llvm-project/blob/fcf6800506862586e2d409aaa03a1cff818edfcc/clang/lib/Driver/ToolChains/MSVC.cpp#L1490-L1539

If I'm wrong, I think it could still be done with just a mapping/lookup table function (though more tedious and fragile).

I feel a lot of folks would benefit from this. It's not always the most intuitive process to translate MSVC cl.exe flags to clang.exe flags.

Have learned that you can pass -### to clang-cl.exe to print execution commands to stdout, like so:

λ  clang-cl /c /EHa /EHc -### a.c
clang version 12.0.0
Target: x86_64-pc-windows-msvc
Thread model: posix
InstalledDir: C:\Program Files\LLVM\bin
 (in-process)
 "C:\\Program Files\\LLVM\\bin\\clang-cl.exe" "-cc1" "-triple" "x86_64-pc-windows-msvc19.28.29913" "-emit-obj" "-mrelax-all" "-mincremental-linker-compatible" "--mrelax-relocations" "-disable-free" "-main-file-name" "a.c" "-mrelocation-model" "pic" "-pic-level" "2" "-mframe-pointer=none" "-relaxed-aliasing" "-fmath-errno" "-fno-rounding-math" "-mconstructor-aliases" "-munwind-tables" "-target-cpu" "x86-64" "-mllvm" "-x86-asm-syntax=intel" "-tune-cpu" "generic" "-D_MT" "-flto-visibility-public-std" "--dependent-lib=libcmt" "--dependent-lib=oldnames" "-stack-protector" "2" "-fexceptions" "-fms-volatile" "-fdiagnostics-format" "msvc" "-resource-dir" "C:\\Program Files\\LLVM\\lib\\clang\\12.0.0" "-internal-isystem" "C:\\Program Files\\LLVM\\lib\\clang\\12.0.0\\include" "-internal-isystem" "C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\Community\\VC\\Tools\\MSVC\\14.28.29910\\include" "-internal-isystem" "C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\Community\\VC\\Tools\\MSVC\\14.28.29910\\atlmfc\\include" "-internal-isystem" "C:\\Program Files (x86)\\Windows Kits\\10\\Include\\10.0.19041.0\\ucrt" "-internal-isystem" "C:\\Program Files (x86)\\Windows Kits\\10\\include\\10.0.19041.0\\shared" "-internal-isystem" "C:\\Program Files (x86)\\Windows Kits\\10\\include\\10.0.19041.0\\um" "-internal-isystem" "C:\\Program Files (x86)\\Windows Kits\\10\\include\\10.0.19041.0\\winrt" "-fdebug-compilation-dir" "C:\\Users\\rayga" "-ferror-limit" "19" "-fmessage-length=120" "-fno-use-cxa-atexit" "-fms-extensions" "-fms-compatibility" "-fms-compatibility-version=19.28.29913" "-fdelayed-template-parsing" "-fcolor-diagnostics" "-faddrsig" "-o" "a.obj" "-x" "c" "a.c"

So maybe it's possible to script/automate the generation of the conversion by writing an array of all possible flags (with dummy input where needed), and iterating them one-by-one and taking only the diff between each invocation to get the converted output of the flag.

Then you'd have a mapping from clang-cl -> clang flag generated somewhat automatically.

---

Alternatively, something like this could be used as a duct-tape hack maybe:

#!/bin/sh
$clang_flags = $(clang-cl.exe "-###" "$@") # Do some processing on the text too so it's only the clang flags
zig cc $clang_flags

If there's still interest in this or a good way of implementing it, maybe I could try to take a crack it.
Or if it's easy, someone familiar with Zig, the codebase, and the dev workflow could crank it out.

=)

[will-ca]

Wouldn't making this work out-of-the-box require the user to also have the MSVCRT and SDK, which are both huge and not freely licensed/forbidden from redistribution?

E.G. I have followed this as an example and tool for using Clang/CL:

https://jake-shadle.github.io/xwin/

https://github.com/Jake-Shadle/xwin

[safasofuoglu]

possibly related:
https://internals.rust-lang.org/t/pre-rfc-remove-rusts-dependency-on-visual-studio-in-4-complex-steps/16708
microsoft/STL#2046 (comment)

[kassane]

Wouldn't making this work out-of-the-box require the user to also have the MSVCRT and SDK, which are both huge and not freely licensed/forbidden from redistribution?

E.G. I have followed this as an example and tool for using Clang/CL:

https://jake-shadle.github.io/xwin/

https://github.com/Jake-Shadle/xwin

Zig with Xwin test: https://github.com/kassane/xwin-zig-test

[ghost]

note that Xwin is not ideal, as it does not handle (and owner refuses to handle) important parts of MSVC such as cl.exe. I hope that any Zig foray into this area will have that as an option.

[andrewrk]

I am convinced this is not worth it.

Note that this proposal is about the CLI interface of Zig. It has already been possible for a long time to use Zig as a replacement for MSVC.

[ghost]

It has already been possible for a long time to use Zig as a replacement for MSVC.

you mean in the context of headers and libraries. in the context of executables such as cl.exe, Zig currently cannot replace that. If I am wrong about that fact, I will be VERY happy to hear it.

[andrewrk]

Zig supports compiling and linking C/C++ code