[PATCH] D52773: clang-cl: Add /showFilenames option (PR31957)

[Stephen Kelly via Phabricator via cfe-commits]

steveire added inline comments.


================
Comment at: lib/Frontend/CompilerInvocation.cpp:792
   Opts.MainFileName = Args.getLastArgValue(OPT_main_file_name);
+  if (Args.hasArg(OPT_echo_main_file_name))
+    llvm::outs() << Opts.MainFileName << "\n";
----------------
hans wrote:
> zturner wrote:
> > steveire wrote:
> > > I'll have to keep a patch around anyway for myself locally to remove this condition. But maybe someone else will benefit from this.
> > > 
> > > What do you think about changing CMake to so that this is passed by default when using Clang-CL?
> > > 
> > Do you mean llvms cmake?  Or cmake itself?  Which generator are you using?
> Can't you just configure your build to pass the flag to clang-cl?
> 
> I suppose CMake could be made to do that by default when using clang-cl versions that support the flag and using the MSBuild generator, but that's for the CMake community to decide I think. Or perhaps our VS integration could do that, but it gets tricky because it needs to know whether the flag is supported or not.
I mean upstream cmake. My suggestion is independent of the generator, but it would depend on what Brad decides anyway. I don't intend to implement it, just report it.

I only have one clang but I have multiple buildsystems, and I don't want to have to add a new flag too all of them. In each toplevel CMakeLists everyone will need this to make use of the flag:

```

# Have to remember to use "${CMAKE_CXX_SIMULATE_ID}" instead of 
# Undecorated "CMAKE_CXX_SIMULATE_ID" because there is a 
# variable named "MSVC" and
# the way CMake variables and the "if()" command work requires this. 
if (CMAKE_CXX_COMPILER_ID STREQUAL Clang 
        AND ${CMAKE_CXX_SIMULATE_ID} STREQUAL MSVC)
    # CMake does not have explicit Clang-CL support yet.
    # It should have a COMPILER_ID for it.
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /showFilename")
    # etc
endif()
```

Upstream CMake can have the logic to add the flag instead.


https://reviews.llvm.org/D52773