[clang-linker-wrapper] Add error handling for missing linker path (llvm#113613)

In clang-linker-wrapper, we do not explicitly check if --linker-path is
provided.
This PR adds a check to capture this.

Thanks

---------

Signed-off-by: Arvind Sudarsanam <[email protected]>

Author: asudarsa

clang/test/Driver/linker-wrapper.c

@@ -250,3 +250,7 @@ __attribute__((visibility("protected"), used)) int x;
 //       MLLVM-SAME: -Xlinker -mllvm=-pass-remarks=foo,bar
 //  OFFLOAD-OPT-NOT: -Xlinker -mllvm=-pass-remarks=foo,bar
 // OFFLOAD-OPT-SAME: {{$}}
+
+// Error handling when --linker-path is not provided for clang-linker-wrapper
+// RUN: not clang-linker-wrapper 2>&1 | FileCheck --check-prefix=LINKER-PATH-NOT-PROVIDED %s
+// LINKER-PATH-NOT-PROVIDED: linker path missing, must pass 'linker-path'

clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp

@@ -370,6 +370,8 @@ Error runLinker(ArrayRef<StringRef> Files, const ArgList &Args) {
   // Render the linker arguments and add the newly created image. We add it
   // after the output file to ensure it is linked with the correct libraries.
   StringRef LinkerPath = Args.getLastArgValue(OPT_linker_path_EQ);
+  if (LinkerPath.empty())
+    return createStringError("linker path missing, must pass 'linker-path'");
   ArgStringList NewLinkerArgs;
   for (const opt::Arg *Arg : Args) {
     // Do not forward arguments only intended for the linker wrapper.