clang-cl support?

[nico]

Since the beta now has MSVC (yay!), maybe it could offer clang-cl too? clang-cl is part of the normal clang distribution, it runs clang in a driver mode that understands cl.exe-like options and it enables a few language extensions so that the MSVC headers can be parsed.

[nico]

If I wanted to help with this, what would I have to do?

[mattgodbolt]

Hi there: grab the source, get it running (should be as per the README) and start hacking! To start with edit the etc/config/c++.local.properties and override the compiler list (see etc/config/c++.defaults.properties etc). to be something like

compilers=clang-cl390
compiler.clang-cl390.exe=/path/to/clang/cl
compiler.clang-cl390.name=Clang CL 3.9.0

...and then see how it goes! If you need to start overriding behaviour for clang-cl specifically, you can set the compiler.clang-390.type=somethingnew and then create a file in lib/compilers/somethingnew.js in the same vein as the other files in that directory.

And the send a PR :) (NB the .local. files don't go into source control, so you'll need to give me an example) I can generalise anything that doesn't fit spefically into the CE AWS setup!

And of course: email or message me (email is as per Help menu; messaging is best on the cpplang slack) if I can help unblock you!

[nico]

I played with this a bit. (Took a while 'cause compiler-explorer needed a newer node than available on my system.)

This makes the compiler show up and makes it kind of functional:

$ cat etc/config/c++.local.properties 
compilers=clang-cl
defaultCompiler=clang_cl

compiler.clang-cl.exe=/usr/local/google/home/thakis/src/llvm-build-nolibcxx/bin/clang-cl
compiler.clang-cl.name=clang-cl
compiler.clang-cl.compilerType=CL
compiler.clang-cl.versionFlag=/?
compiler.clang-cl.versionRe=^USAGE: clang-\S* \[options\] <inputs>$

However, clang-cl is a native linux binary (on linux; on Windows it's a native Windows binary of course) and doesn't have to run under wine. CL.js always passes 'Z:' + fn as temp file, which doesn't work without wine. So I hacked that up to

diff --git a/lib/compilers/CL.js b/lib/compilers/CL.js
index b165773..55fda82 100644
--- a/lib/compilers/CL.js
+++ b/lib/compilers/CL.js
@@ -39,16 +39,19 @@ function compileCl(info, env) {
             }
             return origExec(command, args, options);
         };
-        compile.filename = function (fn) {
-            return 'Z:' + fn;
-        };
+        // FIXME: Only do this when wine is actually needed (it isn't for
+        // clang-cl)
+        //compile.filename = function (fn) {
+            //return 'Z:' + fn;
+        //};
     }
     compile.supportsObjdump = function () {
         return false;

With this, I can pass CL-style options to clang-cl and I even get disassembly if I click the buttons just right. One issue is that clang-cl produces regular clang-style assembly and it also doesn't support /FAsc (it does support /FA), so the CL assembly parser gets kind of confused.

It probably makes sense to add something like

group.cl19.options=/I/opt/compiler-explorer/windows/10.0.10240.0/ucrt/ /I/opt/compiler-explorer/windows/14.0.24629/lib/native/include/

to the .properties file. (Even better: If we use -imsvc instead of /I, then the system directories will be treated as system include directories and clang-cl won't emit warnings for them -- see https://docs.google.com/presentation/d/1oxNHaVjA9Gn_rTzX6HIpJHP7nXRua_0URXxxJ3oYRq0/edit#slide=id.g71ecd450e_2_831 for some details) but I couldn't test that since I don't have these files on my Linux box.

So it's fairly easy to get something that kind-of works. I'm not sure if you'd prefer if there was a lib/compilers/clang-cl.js that's kind-of-but-not-quite like lib/compilers/CL.js (similar flags, but no need for wine, and has clang-style disassembly output instead of MSVC-style) or if you prefer tweaking CL.js to work for both.

[mattgodbolt]

Great progress: thanks so much!

[timmy-ms]

Using #1967 to track this.