[PATCH] D85998: Add clang-cl "vctoolsdir" option to specify the location of the msvc toolchain

Mon Aug 24 13:00:42 PDT 2020

zahen added inline comments.

================
Comment at: clang/test/Driver/cl-options.c:686
+// vctoolsdir is handled by the driver; just check that we don't error. Pass -c because fakedir isn't a real toolchain path
+// RUN: %clang_cl -c -vctoolsdir fakedir -- %s 2>&1
+
----------------
zahen wrote:
> hans wrote:
> > zahen wrote:
> > > hans wrote:
> > > > aganea wrote:
> > > > > Check that we're not detecting a local installation, and that we fallback to the default triple 19.11, ie.
> > > > > ```
> > > > > // RUN: %clang_cl ... -vctoolsdir "" -### | FileCheck %s --check-prefix VCTOOLSDIR
> > > > > // VCTOOLSDIR: "-cc1" "-triple" "x86_64-pc-windows-msvc19.11.0"
> > > > > ```
> > > > Maybe add a comment explaining the purpose of the test.
> > > > 
> > > > And would it be possible to have a test where -vctoolsdir is set to something, to see that it's picked up correctly?
> > > What's the expectation on the test boxes?  I can author such a test but it would be very brittle unless we have a spec for how VS should be installed.
> > I'd suggest passing -vctoolsdir "/foo" and check that some /foo dir is getting passed as a system include dir to cc1, and that the link.exe invocation is under /foo.
> > 
> > I don't think it would be brittle.
> Clever idea! I'll do it that way and key off the "ignored directory" warning that's emitted.
Did further digging and the path test would depend on other environment variables.  If the %INCLUDE% variable is set, as it is by vcvars.bat, those paths are adopted and VCToolChainPath is not used.  I'm hesitant to change that logic without stronger motivation.

Other ideas for a test that would work run both from a vc command prompt and a vanilla command prompt?  I don't see anything else in the full verbose invocation to key off of:

```
D:\repos\llvm\llvm-project\build\Debug\bin>clang-cl -vctoolsdir "/fake" -v main.cpp
clang version 12.0.0 (https://github.com/llvm/llvm-project 537f5483fe4e09c39ffd7ac837c00b50dd13d676)
Target: x86_64-pc-windows-msvc
Thread model: posix
InstalledDir: D:\repos\llvm\llvm-project\build\Debug\bin
 "D:\\repos\\llvm\\llvm-project\\build\\Debug\\bin\\clang-cl.exe" -cc1 -triple x86_64-pc-windows-msvc19.11.0 -emit-obj -mrelax-all -mincremental-linker-compatible --mrelax-relocations -disable-free -main-file-name main.cpp -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 -D_MT -flto-visibility-public-std --dependent-lib=libcmt --dependent-lib=oldnames -stack-protector 2 -fms-volatile -fdiagnostics-format msvc -v -resource-dir "D:\\repos\\llvm\\llvm-project\\build\\Debug\\lib\\clang\\12.0.0" -internal-isystem "D:\\repos\\llvm\\llvm-project\\build\\Debug\\lib\\clang\\12.0.0\\include" -internal-isystem "C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\Enterprise\\VC\\Tools\\MSVC\\14.27.29110\\ATLMFC\\include" -internal-isystem "C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\Enterprise\\VC\\Tools\\MSVC\\14.27.29110\\include" -internal-isystem "C:\\Program Files (x86)\\Windows Kits\\NETFXSDK\\4.8\\include\\um" -internal-isystem "C:\\Program Files (x86)\\Windows Kits\\10\\include\\10.0.18362.0\\ucrt" -internal-isystem "C:\\Program Files (x86)\\Windows Kits\\10\\include\\10.0.18362.0\\shared" -internal-isystem "C:\\Program Files (x86)\\Windows Kits\\10\\include\\10.0.18362.0\\um" -internal-isystem "C:\\Program Files (x86)\\Windows Kits\\10\\include\\10.0.18362.0\\winrt" -internal-isystem "C:\\Program Files (x86)\\Windows Kits\\10\\include\\10.0.18362.0\\cppwinrt" -fdeprecated-macro -fdebug-compilation-dir "D:\\repos\\llvm\\llvm-project\\build\\Debug\\bin" -ferror-limit 19 -fmessage-length=121 -fno-use-cxa-atexit -fms-extensions -fms-compatibility -fms-compatibility-version=19.11 -std=c++14 -fdelayed-template-parsing -fcolor-diagnostics -faddrsig -o "C:\\Users\\zahen\\AppData\\Local\\Temp\\main-8f329a.obj" -x c++ main.cpp
clang -cc1 version 12.0.0 based upon LLVM 12.0.0git default target x86_64-pc-windows-msvc
#include "..." search starts here:
#include <...> search starts here:
 D:\repos\llvm\llvm-project\build\Debug\lib\clang\12.0.0\include
 C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Tools\MSVC\14.27.29110\ATLMFC\include
 C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Tools\MSVC\14.27.29110\include
 C:\Program Files (x86)\Windows Kits\NETFXSDK\4.8\include\um
 C:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\ucrt
 C:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\shared
 C:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\um
 C:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\winrt
 C:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\cppwinrt
End of search list.
 "link.exe" -out:main.exe -nologo "C:\\Users\\zahen\\AppData\\Local\\Temp\\main-8f329a.obj"
clang-cl: error: unable to execute command: program not executable
clang-cl: error: linker command failed with exit code 1 (use -v to see invocation)
```

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https://reviews.llvm.org/D85998