[clang][Driver] Fix crash with unsupported architectures in MinGW and CrossWindows.

[k-mana]

Summary

MinGW and CrossWindows crash if the target is an unsupported target architecture.
Changed it to emit an error message.

Fixes https://github.com/llvm/llvm-project/issues/59545

[shafik]

Thank you for this fix. Can you please add a summary in the details explaining the motivation for this fix and a link to the github bug report as well.

[fhahn]

Sorry, I am not familiar at all with this code. Perhaps @shafik could suggest more appropriate reviewers

[mstorsjo]

I think the code changes make sense; these are trivial to hit by a user, so they shouldn't be llvm_unreachable.

clang/test/Driver/unsupported-target-arch.c

33

Separate side note; the suggested option -triple isn't really a clang driver level option, and -arch is only relevant for darwin targets (AFAIK) - so maybe the error message text should be revised?

[mstorsjo]

LGTM. If you don’t have commit access, please say your preferred git author name for the commit, i.e. Real Name <email@address>.

[k-mana]

I don't have commit access.
Please commit at KOMATA Manabu <[e-mail]>.

[MaskRay]

Looks great!

clang/test/Driver/unsupported-target-arch.c

33

The part ", please use -triple or -arch" is almost always wrong.

For cc1, the error is due to a specified but unknown -triple, we should not suggest specifying -triple.
For driver, -triple and -arch are not driver options.

I just removed the hint from the diagnostic.

[mstorsjo]

clang/test/Driver/unsupported-target-arch.c

33

-arch is a driver option, for darwin targets though. But I agree that it's probably best to leave it out since it's more misleading than helping here (and -triple is indeed not a relevant option here).

clang/lib/Driver/ToolChains/CrossWindows.cpp

void tools::CrossWindows::Linker::ConstructJob(
   if (Args.hasArg(options::OPT_rdynamic))
     CmdArgs.push_back("-export-dynamic");
   if (Args.hasArg(options::OPT_s))
     CmdArgs.push_back("--strip-all");
 
   CmdArgs.push_back("-m");
   switch (TC.getArch()) {
   default:
-    llvm_unreachable("unsupported architecture");
+    D.Diag(diag::err_target_unknown_triple) << TC.getEffectiveTriple().str();
+    break;
   case llvm::Triple::arm:
   case llvm::Triple::thumb:
     // FIXME: this is incorrect for WinCE
     CmdArgs.push_back("thumb2pe");
     break;
   case llvm::Triple::aarch64:
     CmdArgs.push_back("arm64pe");
     break;

clang/lib/Driver/ToolChains/MinGW.cpp

void tools::MinGW::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   case llvm::Triple::thumb:
     // FIXME: this is incorrect for WinCE
     CmdArgs.push_back("thumb2pe");
     break;
   case llvm::Triple::aarch64:
     CmdArgs.push_back("arm64pe");
     break;
   default:
-    llvm_unreachable("Unsupported target architecture.");
+    D.Diag(diag::err_target_unknown_triple) << TC.getEffectiveTriple().str();
   }
 
   Arg *SubsysArg =
       Args.getLastArg(options::OPT_mwindows, options::OPT_mconsole);
   if (SubsysArg && SubsysArg->getOption().matches(options::OPT_mwindows)) {
     CmdArgs.push_back("--subsystem");
     CmdArgs.push_back("windows");
   } else if (SubsysArg &&

clang/test/Driver/unsupported-target-arch.c

 //
 // RUN: not %clang --target=noarch-unknown-netbsd -o %t.o %s 2> %t.err
 // RUN: FileCheck --input-file=%t.err --check-prefix=CHECK-NOARCH-NETBSD %s
 // CHECK-NOARCH-NETBSD: error: unknown target triple 'noarch-unknown-netbsd', please use -triple or -arch
 //
 // RUN: not %clang --target=noarch-unknown-nacl -o %t.o %s 2> %t.err
 // RUN: FileCheck --input-file=%t.err --check-prefix=CHECK-NOARCH-NACL %s
 // CHECK-NOARCH-NACL:  error: the target architecture 'noarch' is not supported by the target 'Native Client'
+//
+// RUN: not %clang --target=noarch-unknown-windows-gnu -o %t.o %s 2> %t.err
+// RUN: FileCheck --input-file=%t.err --check-prefix=CHECK-NOARCH-MINGW %s
+// CHECK-NOARCH-MINGW: error: unknown target triple 'noarch-unknown-windows-gnu', please use -triple or -arch
+//
+// RUN: not %clang --target=noarch-unknown-windows-itanium -o %t.o %s 2> %t.err
+// RUN: FileCheck --input-file=%t.err --check-prefix=CHECK-NOARCH-CROSSWINDOWS %s
+// CHECK-NOARCH-CROSSWINDOWS: error: unknown target triple 'noarch-unknown-windows-itanium', please use -triple or -arch