NFC, use structured binding to simplify the code in SourceManager.cpp.

Author: hokein

clang/lib/Basic/SourceManager.cpp

@@ -1795,9 +1795,8 @@ void SourceManager::associateFileChunkWithMacroArgExp(
     // spelling range and if one is itself a macro argument expansion, recurse
     // and associate the file chunk that it represents.
 
-    FileID SpellFID; // Current FileID in the spelling range.
-    unsigned SpellRelativeOffs;
-    std::tie(SpellFID, SpellRelativeOffs) = getDecomposedLoc(SpellLoc);
+    // Current FileID in the spelling range.
+    auto [SpellFID, SpellRelativeOffs] = getDecomposedLoc(SpellLoc);
     while (true) {
       const SLocEntry &Entry = getSLocEntry(SpellFID);
       SourceLocation::UIntTy SpellFIDBeginOffs = Entry.getOffset();
@@ -1879,9 +1878,7 @@ SourceManager::getMacroArgExpandedLocation(SourceLocation Loc) const {
   if (Loc.isInvalid() || !Loc.isFileID())
     return Loc;
 
-  FileID FID;
-  unsigned Offset;
-  std::tie(FID, Offset) = getDecomposedLoc(Loc);
+  auto [FID, Offset] = getDecomposedLoc(Loc);
   if (FID.isInvalid())
     return Loc;