[Driver] -save-temps issue with files in CWD (#7955)

When using -save-temps against fails in the $CWD, the driver was
avoiding creating the intermediate files in the $CWD and creating them
in /tmp. A previous modification to improve our behaviors with potential
clashing intermediate files when working with llvm-foreach compilations
inadvertently modified the check for the output name matching the base
input name. Put this check back in.

Author: mdtoguchi

clang/lib/Driver/Driver.cpp

@@ -9015,7 +9015,7 @@ const char *Driver::GetNamedOutputPath(Compilation &C, const JobAction &JA,
   if (isSaveTempsEnabled()) {
     // If we're saving temps and the temp file conflicts with any
     // input/resulting file, then avoid overwriting.
-    if (!AtTopLevel) {
+    if (!AtTopLevel && NamedOutput == BaseName) {
       bool SameFile = false;
       SmallString<256> Result;
       llvm::sys::fs::current_path(Result);

clang/test/Driver/save-temps.c

@@ -93,3 +93,11 @@
 // CHECK-SAVE-TEMPS-CMSE: -cc1as
 // CHECK-SAVE-TEMPS-CMSE: +8msecext
 // CHECK-SAVE-TEMPS-CMSE-NOT: '+cmse' is not a recognized feature for this target (ignoring feature)
+
+// Usage of -save-temps with a file in $CWD should create the intermediate
+// files _not_ in /tmp.
+//
+// RUN: touch dummy.c
+// RUN: %clang -save-temps dummy.c -### 2>&1  \
+// RUN:   | FileCheck %s -check-prefix=CHECK-CWD-FILE
+// CHECK-CWD-FILE: clang{{.*}} "-o" "dummy.ii"