[clang][driver] Fix multiarch output name with -Wl arg

[keith]

Summary

Previously if you passed a -Wl,-foo _before_ the source filename, the
first InputInfos, which is used for the base input name would be an
InputArg kind, which would never have a base input name. Now we use
that by default, but pick the first InputInfo that is of kind
Filename to get the name from if there is one.

[kastiglione]

clang/lib/Driver/Driver.cpp

4700

maybe adjust this comment to emphasize first _file_ input

[keith]

Update comment

[JDevlieghere]

LGTM

clang/lib/Driver/Driver.cpp

for (const Action *Input : Inputs) {
     // FIXME: Clean this up.
     bool SubJobAtTopLevel =
         AtTopLevel && (isa<DsymutilJobAction>(A) || isa<VerifyJobAction>(A));
     InputInfos.push_back(BuildJobsForAction(
         C, Input, TC, BoundArch, SubJobAtTopLevel, MultipleArchs, LinkingOutput,
         CachedResults, A->getOffloadingDeviceKind()));
   }
 
-  // Always use the first input as the base input.
+  // Always use the first file input as the base input.
   const char *BaseInput = InputInfos[0].getBaseInput();
+  for (auto &Info : InputInfos) {
+    if (Info.isFilename()) {
+      BaseInput = Info.getBaseInput();
+      break;
+    }
+  }
 
   // ... except dsymutil actions, which use their actual input as the base
   // input.
   if (JA->getType() == types::TY_dSYM)
     BaseInput = InputInfos[0].getFilename();
 
   // ... and in header module compilations, which use the module name.
   if (auto *ModuleJA = dyn_cast<HeaderModulePrecompileJobAction>(JA))

clang/test/Driver/darwin-dsymutil.c

 //
 // RUN: %clang -target x86_64-apple-darwin10 \
 // RUN:   -arch x86_64 -arch arm64 -ccc-print-bindings %s 2> %t
 // RUN: FileCheck --check-prefix=CHECK-MULTIARCH-OUTPUT-NAME < %t %s
 //
 // CHECK-MULTIARCH-OUTPUT-NAME: "x86_64-apple-darwin10" - "darwin::Linker", inputs: ["{{.*}}{{/|\\}}darwin-dsymutil-x86_64.o"], output: "{{.*}}{{/|\\}}darwin-dsymutil-x86_64.out"
 // CHECK-MULTIARCH-OUTPUT-NAME: "arm64-apple-darwin10" - "darwin::Linker", inputs: ["{{.*}}{{/|\\}}darwin-dsymutil-arm64.o"], output: "{{.*}}{{/|\\}}darwin-dsymutil-arm64.out"
 // CHECK-MULTIARCH-OUTPUT-NAME: "arm64-apple-darwin10" - "darwin::Lipo", inputs: ["{{.*}}{{/|\\}}darwin-dsymutil-x86_64.out", "{{.*}}{{/|\\}}darwin-dsymutil-arm64.out"], output: "a.out"
+//
+// RUN: %clang -target x86_64-apple-darwin10 \
+// RUN:   -Wl,-foo -arch x86_64 -arch arm64 -ccc-print-bindings %s 2> %t
+// RUN: FileCheck --check-prefix=CHECK-MULTIARCH-OUTPUT-NAME-WITH-ARG < %t %s
+//
+// CHECK-MULTIARCH-OUTPUT-NAME-WITH-ARG: "x86_64-apple-darwin10" - "darwin::Linker", inputs: [(input arg), "{{.*}}{{/|\\}}darwin-dsymutil-x86_64.o"], output: "{{.*}}{{/|\\}}darwin-dsymutil-x86_64.out"
+// CHECK-MULTIARCH-OUTPUT-NAME-WITH-ARG: "arm64-apple-darwin10" - "darwin::Linker", inputs: [(input arg), "{{.*}}{{/|\\}}darwin-dsymutil-arm64.o"], output: "{{.*}}{{/|\\}}darwin-dsymutil-arm64.out"
+// CHECK-MULTIARCH-OUTPUT-NAME-WITH-ARG: "arm64-apple-darwin10" - "darwin::Lipo", inputs: ["{{.*}}{{/|\\}}darwin-dsymutil-x86_64.out", "{{.*}}{{/|\\}}darwin-dsymutil-arm64.out"], output: "a.out"
 
 // Check that we only use dsymutil when needed.
 //
 // RUN: touch %t.o
 // RUN: %clang -target x86_64-apple-darwin10 -ccc-print-bindings \
 // RUN:   -o foo %t.o -g 2> %t
 // RUN: not grep "Dsymutil" %t
 
 // Check that we don't crash when translating arguments for dsymutil.
 // RUN: %clang -m32 -arch x86_64 -g %s -###