[clang] [MinGW] Pass --no-demangle through to the mingw linker

[mstorsjo]

Summary

Clang has custom handling of --no-demangle, where it is removed
from the input -Wl and -Xlinker options, and readded specifically
by the drivers where it's known to be supported.

Both ld.bfd and lld support the --no-demangle option.

[mstorsjo]

Adding more potential reviewers. For context, see https://github.com/llvm/llvm-project/blob/llvmorg-14-init/clang/lib/Driver/Driver.cpp#L335-L353 where the original option is filtered out.

[Ericson2314]

Not sure what the exact division of labor is between the GNU and MinGW backends, but assuming there is no way to share this between them the patch looks good.

[mstorsjo]

In D114064#3216147, @Ericson2314 wrote:

Not sure what the exact division of labor is between the GNU and MinGW backends, but assuming there is no way to share this between them the patch looks good.

Yeah. Also at this point, this option should probably rather be handled as opt-out for targets that don’t support it, instead of having every single target do manual work to pass it through.

Additionally, this probably doesn’t handle sequences of --no-demangle --demangle correctly, but this just gets this target to the same level as e.g. GNU.

[MaskRay]

LGTM.

clang/lib/Driver/ToolChains/MinGW.cpp

if (Args.hasArg(options::OPT_mdll) || Args.hasArg(options::OPT_shared)) {
     CmdArgs.push_back("-e");
     if (TC.getArch() == llvm::Triple::x86)
       CmdArgs.push_back("_DllMainCRTStartup@12");
     else
       CmdArgs.push_back("DllMainCRTStartup");
     CmdArgs.push_back("--enable-auto-image-base");
   }
 
+  if (Args.hasArg(options::OPT_Z_Xlinker__no_demangle))
+    CmdArgs.push_back("--no-demangle");
+
   CmdArgs.push_back("-o");
   const char *OutputFile = Output.getFilename();
   // GCC implicitly adds an .exe extension if it is given an output file name
   // that lacks an extension.
   // GCC used to do this only when the compiler itself runs on windows, but
   // since GCC 8 it does the same when cross compiling as well.
   if (!llvm::sys::path::has_extension(OutputFile)) {
     CmdArgs.push_back(Args.MakeArgString(Twine(OutputFile) + ".exe"));

clang/test/Driver/Xlinker-args.c

 // Check that we extract --no-demangle from '-Xlinker' and '-Wl,', since that
 // was a collect2 argument.
 
 // RUN: %clang -target i386-apple-darwin9 -### \
 // RUN:   -Xlinker one -Xlinker --no-demangle \
 // RUN:   -Wl,two,--no-demangle,three -Xlinker four -z five -r %s 2> %t
 // RUN: FileCheck -check-prefix=DARWIN < %t %s
 
 /// -T is reordered to the last to make sure -L takes precedence.
 // RUN: %clang -target x86_64-pc-linux-gnu -### \
 // RUN:   -e _start -T a.lds -Xlinker one -Xlinker --no-demangle \
 // RUN:   -Wl,two,--no-demangle,three -Xlinker four -z five -r %s 2> %t
 // RUN: FileCheck -check-prefix=LINUX < %t %s
 
+/// Check that --no-demangle gets forwarded to the mingw linker
+// RUN: %clang -target x86_64-w64-mingw32 -### \
+// RUN:   -Wl,--no-demangle %s 2> %t
+// RUN: FileCheck -check-prefix=MINGW < %t %s
+
 // RUN: %clang -target powerpc-unknown-aix -### \
 // RUN:   -b one -b two %s 2> %t
 // RUN: FileCheck -check-prefix=AIX < %t %s
 
 // RUN: %clang -target powerpc-unknown-linux -### \
 // RUN:   -b one %s 2> %t
 // RUN: FileCheck -check-prefix=NOT-AIX < %t %s
 
 // DARWIN-NOT: --no-demangle
 // DARWIN: "one" "two" "three" "four" "-z" "five" "-r"
 // LINUX: "--no-demangle" "-e" "_start" "one" "two" "three" "four" "-z" "five" "-r" {{.*}} "-T" "a.lds"
+// MINGW: "--no-demangle"
 // AIX: "-b" "one" "-b" "two"
 // NOT-AIX: error: unsupported option '-b' for target 'powerpc-unknown-linux'
 
 // Check that we forward '-Xlinker' and '-Wl,' on Windows.
 // RUN: %clang -target i686-pc-win32 -fuse-ld=link -### \
 // RUN:   -Xlinker one -Wl,two %s 2>&1 | \
 // RUN:   FileCheck -check-prefix=WIN %s
 // WIN: link.exe
 // WIN: "one"
 // WIN: "two"