[PATCH] D80876: [clang] Default to windows response files when running on windows

[Sam Clegg via Phabricator via cfe-commits]

sbc100 marked an inline comment as done.
sbc100 added inline comments.


================
Comment at: clang/tools/driver/driver.cpp:391
+    if (ClangCLMode ||
+        llvm::Triple(llvm::sys::getProcessTriple()).isOSWindows())
+      Tokenizer = &llvm::cl::TokenizeWindowsCommandLine;
----------------
probinson wrote:
> Testing the triple is a functional change.  I should think the test for CL mode is sufficient.  Note that for PS4 we run on Windows but use a GNU-compatible command line and response-file style.  If you want Windows-style on Windows, invoke the compiler as "clang-cl" instead of "clang".
Yes this is a functional change.  It changes the default when running on windows.    I will see if I can write a (windows-only) test for it.

Some more background for why I think this change is right way to go:

In the emscripten toolchain we run clang as a cross compiler, we don't want cl.exe emulation.

We drive the compiler and other tools from a python script and we create response files whenever a command line is tool long.

 It doesn't make sense to me that we should use windows response files for all other tools except for `clang`.     In particular, `llvm-ar`, `llc`, `opt`, `wasm-ld` all default to windows response files on windows.  

The function in question in our toolchain looks like this:

```
def generate_response_file(command):
    if is_windows:
       use_windows_style
    else:
       use_gnu_style

```

Without this change I have to write something like this:

```
def generate_response_file(command):
   # On windows all the tools we run use windows style response files.
   # Except for clang (for some reason?).
    if is_windows and 'clang.exe' not in command[0] :
       use_windows_style
    else:
       use_gnu_style

```

I don't see why clang would want to be different here.     Can you think of any reason?



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https://reviews.llvm.org/D80876