[clang] [MinGW] Tolerate mingw specific linker options during compilation (llvm#67891)

Prior to 591c4b6, the mingw specific
linker options -mthreads, -mconsole, -mwindows and -mdll would be
tolerated also at compile time, but generating a warning about being
unused.

After that commit, they were marked as target specific, which means that
it's an error if they're unused (which would consider them used for the
wrong target). These specific options are only relevant when linking,
but we want to tolerate them at compile time too, like before.

This was fixed for -mthreads in
a79995c, while the other options didn't
seem to be commonly used during compilation.

After the 17.x release, we've got more reports about this actually being
an issue, in llvm#64464. Therefore, apply the same fix for them; marking
them as tolerated for mingw targets during compilation, even if they're
unused. Also add a testcase for -mthreads which was already handled.

Thus, this fixes llvm#64464.

(cherry picked from commit e39de2b)

Adapted from the original commit; the test in the original commit
depended on f39c399. Instead of
using -###, when we're not actually using the printed output of
-###, instead use -fdriver-only.

Author: mstorsjo

clang/lib/Driver/ToolChains/MinGW.cpp

@@ -699,8 +699,11 @@ void toolchains::MinGW::addClangTargetOptions(
     }
   }
 
-  if (Arg *A = DriverArgs.getLastArgNoClaim(options::OPT_mthreads))
-    A->ignoreTargetSpecific();
+  for (auto Opt : {options::OPT_mthreads, options::OPT_mwindows,
+                   options::OPT_mconsole, options::OPT_mdll}) {
+    if (Arg *A = DriverArgs.getLastArgNoClaim(Opt))
+      A->ignoreTargetSpecific();
+  }
 }
 
 void toolchains::MinGW::AddClangCXXStdlibIncludeArgs(

clang/test/Driver/mingw-linker-options.c

@@ -0,0 +1,10 @@
+// RUN: %clang --target=x86_64-windows-gnu -c -mwindows %s -fdriver-only 2>&1 | FileCheck %s --check-prefix=WARNING
+// RUN: %clang --target=x86_64-windows-gnu -c -mconsole %s -fdriver-only 2>&1 | FileCheck %s --check-prefix=WARNING
+// RUN: %clang --target=x86_64-windows-gnu -c -mdll %s -fdriver-only 2>&1 | FileCheck %s --check-prefix=WARNING
+// RUN: %clang --target=x86_64-windows-gnu -c -mthreads %s -fdriver-only 2>&1 | FileCheck %s --check-prefix=WARNING
+// RUN: not %clang --target=x86_64-windows-msvc -c -mwindows %s -fdriver-only 2>&1 | FileCheck %s --check-prefix=ERROR
+// RUN: not %clang --target=x86_64-windows-msvc -c -mconsole %s -fdriver-only 2>&1 | FileCheck %s --check-prefix=ERROR
+// RUN: not %clang --target=x86_64-windows-msvc -c -mdll %s -fdriver-only 2>&1 | FileCheck %s --check-prefix=ERROR
+// RUN: not %clang --target=x86_64-windows-msvc -c -mthreads %s -fdriver-only 2>&1 | FileCheck %s --check-prefix=ERROR
+// WARNING: warning: argument unused during compilation: '{{.*}}' [-Wunused-command-line-argument]
+// ERROR: error: unsupported option '{{.*}}' for target '{{.*}}'