[clang][Driver] Make multiarch output file basenames reproducible

[keith]

Summary

When building a multiarch MachO binary, previously the intermediate
output file names would contain random characters. On macOS this
filename, since it's used when linking, ended up being used as a
stable-ish identifier for the adhoc codesignature of the binary, leading
to non-reproducible binaries. This change uses the architecture, when
available, to create a stable, but unique, basename for the file.

[keith]

Remove debug comment

[JDevlieghere]

LGTM

[keith]

Fix format

[keith]

Fix slashes for windows

[keith]

Fix windows test paths

clang/lib/Driver/Driver.cpp

if (CCGenDiagnostics && A) {
       const char *Middle = Suffix ? "-%%%%%%." : "-%%%%%%";
       std::error_code EC = llvm::sys::fs::createUniqueFile(
           CrashDirectory + Middle + Suffix, TmpName);
       if (EC) {
         Diag(clang::diag::err_unable_to_make_temp) << EC.message();
         return "";
       }
     } else {
+      if (MultipleArchs && !BoundArch.empty()) {
+        TmpName = GetTemporaryDirectory(Split.first);
+        llvm::sys::path::append(TmpName,
+                                Split.first + "-" + BoundArch + "." + Suffix);
+      } else {
         TmpName = GetTemporaryPath(Split.first, Suffix);
       }
+    }
     return C.addTempFile(C.getArgs().MakeArgString(TmpName));
   }
 
   SmallString<128> BasePath(BaseInput);
   SmallString<128> ExternalPath("");
   StringRef BaseName;
 
   // Dsymutil actions should use the full path.

clang/test/Driver/darwin-dsymutil.c

 // RUN: %clang -target x86_64-apple-darwin10 -ccc-print-bindings \
 // RUN:   -o bar/foo -dsym-dir external %s -g 2> %t
 // RUN: FileCheck -Doutfile=bar/foo -Ddsymfile=external/foo.dSYM \
 // RUN:           -check-prefix=CHECK-OUTPUT-NAME < %t %s
 //
 // CHECK-OUTPUT-NAME: "x86_64-apple-darwin10" - "darwin::Linker", inputs: [{{.*}}], output: "[[outfile]]"
 // CHECK-OUTPUT-NAME: "x86_64-apple-darwin10" - "darwin::Dsymutil", inputs: ["[[outfile]]"], output: "[[dsymfile]]"
 
+// Check output name derivation for multiple -arch options.
+//
+// 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"
+
 // 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 -###