[clang] Convert ObjCAtTryStmt to llvm::TrailingObjects

[thakis]

Summary

And make it final while here.

No behavior change.

[hans]

Nice!

Do you think the ObjCAtTryStmt::Create and CreateEmpty methods could be simplified by using totalSizeToAlloc()?

[thakis]

Do you think the ObjCAtTryStmt::Create and CreateEmpty methods could be simplified by using totalSizeToAlloc()?

Oh nice. Done :)

[thakis]

more

clang/include/clang/AST/StmtObjC.h

public:
   }
 
   const_child_range children() const {
     return const_child_range(&AtFinallyStmt, &AtFinallyStmt + 1);
   }
 };
 
 /// Represents Objective-C's \@try ... \@catch ... \@finally statement.
-class ObjCAtTryStmt : public Stmt {
-private:
+class ObjCAtTryStmt final
+    : public Stmt,
+      private llvm::TrailingObjects<ObjCAtTryStmt, Stmt *> {
+  friend TrailingObjects;
+  size_t numTrailingObjects(OverloadToken<Stmt *>) const {
+    return 1 + NumCatchStmts + HasFinally;
+  }
+
   // The location of the @ in the \@try.
   SourceLocation AtTryLoc;
 
   // The number of catch blocks in this statement.
   unsigned NumCatchStmts : 16;
 
   // Whether this statement has a \@finally statement.
   bool HasFinally : 1;
 
   /// Retrieve the statements that are stored after this \@try statement.
   ///
   /// The order of the statements in memory follows the order in the source,
   /// with the \@try body first, followed by the \@catch statements (if any)
   /// and, finally, the \@finally (if it exists).
-  Stmt **getStmts() { return reinterpret_cast<Stmt **> (this + 1); }
-  const Stmt* const *getStmts() const {
-    return reinterpret_cast<const Stmt * const*> (this + 1);
-  }
+  Stmt **getStmts() { return getTrailingObjects<Stmt *>(); }
+  Stmt *const *getStmts() const { return getTrailingObjects<Stmt *>(); }
 
   ObjCAtTryStmt(SourceLocation atTryLoc, Stmt *atTryStmt,
                 Stmt **CatchStmts, unsigned NumCatchStmts,
                 Stmt *atFinallyStmt);
 
   explicit ObjCAtTryStmt(EmptyShell Empty, unsigned NumCatchStmts,
                          bool HasFinally)
     : Stmt(ObjCAtTryStmtClass, Empty), NumCatchStmts(NumCatchStmts),
public:
   SourceLocation getBeginLoc() const LLVM_READONLY { return AtTryLoc; }
   SourceLocation getEndLoc() const LLVM_READONLY;
 
   static bool classof(const Stmt *T) {
     return T->getStmtClass() == ObjCAtTryStmtClass;
   }
 
   child_range children() {
-    return child_range(getStmts(),
-                       getStmts() + 1 + NumCatchStmts + HasFinally);
+    return child_range(
+        getStmts(), getStmts() + numTrailingObjects(OverloadToken<Stmt *>()));
   }
 
   const_child_range children() const {
     return const_child_range(const_cast<ObjCAtTryStmt *>(this)->children());
   }
 };
 
 /// Represents Objective-C's \@synchronized statement.

clang/lib/AST/StmtObjC.cpp

ObjCAtTryStmt::ObjCAtTryStmt(SourceLocation atTryLoc, Stmt *atTryStmt,
   if (HasFinally)
     Stmts[NumCatchStmts + 1] = atFinallyStmt;
 }
 
 ObjCAtTryStmt *ObjCAtTryStmt::Create(const ASTContext &Context,
                                      SourceLocation atTryLoc, Stmt *atTryStmt,
                                      Stmt **CatchStmts, unsigned NumCatchStmts,
                                      Stmt *atFinallyStmt) {
-  unsigned Size =
-      sizeof(ObjCAtTryStmt) +
-      (1 + NumCatchStmts + (atFinallyStmt != nullptr)) * sizeof(Stmt *);
+  size_t Size =
+      totalSizeToAlloc<Stmt *>(1 + NumCatchStmts + (atFinallyStmt != nullptr));
   void *Mem = Context.Allocate(Size, alignof(ObjCAtTryStmt));
   return new (Mem) ObjCAtTryStmt(atTryLoc, atTryStmt, CatchStmts, NumCatchStmts,
                                  atFinallyStmt);
 }
 
 ObjCAtTryStmt *ObjCAtTryStmt::CreateEmpty(const ASTContext &Context,
                                           unsigned NumCatchStmts,
                                           bool HasFinally) {
-  unsigned Size =
-      sizeof(ObjCAtTryStmt) + (1 + NumCatchStmts + HasFinally) * sizeof(Stmt *);
+  size_t Size = totalSizeToAlloc<Stmt *>(1 + NumCatchStmts + HasFinally);
   void *Mem = Context.Allocate(Size, alignof(ObjCAtTryStmt));
   return new (Mem) ObjCAtTryStmt(EmptyShell(), NumCatchStmts, HasFinally);
 }
 
 SourceLocation ObjCAtTryStmt::getEndLoc() const {
   if (HasFinally)
     return getFinallyStmt()->getEndLoc();
   if (NumCatchStmts)
     return getCatchStmt(NumCatchStmts - 1)->getEndLoc();
   return getTryBody()->getEndLoc();
 }