NFC, use structured binding to simplify the code.

Author: hokein

clang/lib/Frontend/ASTUnit.cpp

@@ -2466,9 +2466,7 @@ void ASTUnit::addFileLevelDecl(Decl *D) {
 
   SourceLocation FileLoc = SM.getFileLoc(Loc);
   assert(SM.isLocalSourceLocation(FileLoc));
-  FileID FID;
-  unsigned Offset;
-  std::tie(FID, Offset) = SM.getDecomposedLoc(FileLoc);
+  auto [FID, Offset] = SM.getDecomposedLoc(FileLoc);
   if (FID.isInvalid())
     return;
 

clang/lib/Lex/Lexer.cpp

@@ -929,9 +929,7 @@ static CharSourceRange makeRangeFromFileLocs(CharSourceRange Range,
   }
 
   // Break down the source locations.
-  FileID FID;
-  unsigned BeginOffs;
-  std::tie(FID, BeginOffs) = SM.getDecomposedLoc(Begin);
+  auto [FID, BeginOffs] = SM.getDecomposedLoc(Begin);
   if (FID.isInvalid())
     return {};
 

clang/lib/Serialization/ASTWriter.cpp

@@ -6968,9 +6968,7 @@ void ASTWriter::associateDeclWithFile(const Decl *D, LocalDeclID ID) {
   SourceManager &SM = PP->getSourceManager();
   SourceLocation FileLoc = SM.getFileLoc(Loc);
   assert(SM.isLocalSourceLocation(FileLoc));
-  FileID FID;
-  unsigned Offset;
-  std::tie(FID, Offset) = SM.getDecomposedLoc(FileLoc);
+  auto [FID, Offset] = SM.getDecomposedLoc(FileLoc);
   if (FID.isInvalid())
     return;
   assert(SM.getSLocEntry(FID).isFile());

clang/tools/libclang/Indexing.cpp

@@ -389,9 +389,7 @@ class IndexingFrontendAction : public ASTFrontendAction {
     if (SM.isInSystemHeader(Loc))
       return true; // always skip bodies from system headers.
 
-    FileID FID;
-    unsigned Offset;
-    std::tie(FID, Offset) = SM.getDecomposedLoc(Loc);
+    auto [FID, Offset] = SM.getDecomposedLoc(Loc);
     // Don't skip bodies from main files; this may be revisited.
     if (SM.getMainFileID() == FID)
       return false;

clang/unittests/Index/IndexTests.cpp

@@ -35,9 +35,7 @@ struct Position {
 
   static Position fromSourceLocation(SourceLocation Loc,
                                      const SourceManager &SM) {
-    FileID FID;
-    unsigned Offset;
-    std::tie(FID, Offset) = SM.getDecomposedSpellingLoc(Loc);
+    auto [FID, Offset] = SM.getDecomposedSpellingLoc(Loc);
     Position P;
     P.Line = SM.getLineNumber(FID, Offset);
     P.Column = SM.getColumnNumber(FID, Offset);