[Rewrite] Use auto (NFC)

I'm planning to change the type of BlockByCopyDecls and
BlockByRefDecls to SetVector.  Declaring these iterators with auto
makes it easier to migrate to the new type.

Author: kazutakahirata

clang/lib/Frontend/Rewrite/RewriteObjC.cpp

@@ -3292,8 +3292,8 @@ std::string RewriteObjC::SynthesizeBlockFunc(BlockExpr *CE, int i,
 
   // Create local declarations to avoid rewriting all closure decl ref exprs.
   // First, emit a declaration for all "by ref" decls.
-  for (SmallVectorImpl<ValueDecl *>::iterator I = BlockByRefDecls.begin(),
-       E = BlockByRefDecls.end(); I != E; ++I) {
+  for (auto I = BlockByRefDecls.begin(), E = BlockByRefDecls.end(); I != E;
+       ++I) {
     S += "  ";
     std::string Name = (*I)->getNameAsString();
     std::string TypeString;
@@ -3303,8 +3303,8 @@ std::string RewriteObjC::SynthesizeBlockFunc(BlockExpr *CE, int i,
     S += Name + " = __cself->" + (*I)->getNameAsString() + "; // bound by ref\n";
   }
   // Next, emit a declaration for all "by copy" declarations.
-  for (SmallVectorImpl<ValueDecl *>::iterator I = BlockByCopyDecls.begin(),
-       E = BlockByCopyDecls.end(); I != E; ++I) {
+  for (auto I = BlockByCopyDecls.begin(), E = BlockByCopyDecls.end(); I != E;
+       ++I) {
     S += "  ";
     // Handle nested closure invocation. For example:
     //
@@ -3400,8 +3400,8 @@ std::string RewriteObjC::SynthesizeBlockImpl(BlockExpr *CE, std::string Tag,
 
   if (BlockDeclRefs.size()) {
     // Output all "by copy" declarations.
-    for (SmallVectorImpl<ValueDecl *>::iterator I = BlockByCopyDecls.begin(),
-         E = BlockByCopyDecls.end(); I != E; ++I) {
+    for (auto I = BlockByCopyDecls.begin(), E = BlockByCopyDecls.end(); I != E;
+         ++I) {
       S += "  ";
       std::string FieldName = (*I)->getNameAsString();
       std::string ArgName = "_" + FieldName;
@@ -3429,8 +3429,8 @@ std::string RewriteObjC::SynthesizeBlockImpl(BlockExpr *CE, std::string Tag,
       S += FieldName + ";\n";
     }
     // Output all "by ref" declarations.
-    for (SmallVectorImpl<ValueDecl *>::iterator I = BlockByRefDecls.begin(),
-         E = BlockByRefDecls.end(); I != E; ++I) {
+    for (auto I = BlockByRefDecls.begin(), E = BlockByRefDecls.end(); I != E;
+         ++I) {
       S += "  ";
       std::string FieldName = (*I)->getNameAsString();
       std::string ArgName = "_" + FieldName;
@@ -3448,8 +3448,8 @@ std::string RewriteObjC::SynthesizeBlockImpl(BlockExpr *CE, std::string Tag,
     Constructor += ", int flags=0)";
     // Initialize all "by copy" arguments.
     bool firsTime = true;
-    for (SmallVectorImpl<ValueDecl *>::iterator I = BlockByCopyDecls.begin(),
-         E = BlockByCopyDecls.end(); I != E; ++I) {
+    for (auto I = BlockByCopyDecls.begin(), E = BlockByCopyDecls.end(); I != E;
+         ++I) {
       std::string Name = (*I)->getNameAsString();
         if (firsTime) {
           Constructor += " : ";
@@ -3463,8 +3463,8 @@ std::string RewriteObjC::SynthesizeBlockImpl(BlockExpr *CE, std::string Tag,
           Constructor += Name + "(_" + Name + ")";
     }
     // Initialize all "by ref" arguments.
-    for (SmallVectorImpl<ValueDecl *>::iterator I = BlockByRefDecls.begin(),
-         E = BlockByRefDecls.end(); I != E; ++I) {
+    for (auto I = BlockByRefDecls.begin(), E = BlockByRefDecls.end(); I != E;
+         ++I) {
       std::string Name = (*I)->getNameAsString();
       if (firsTime) {
         Constructor += " : ";
@@ -4439,8 +4439,8 @@ Stmt *RewriteObjC::SynthBlockInitExpr(BlockExpr *Exp,
   if (BlockDeclRefs.size()) {
     Expr *Exp;
     // Output all "by copy" declarations.
-    for (SmallVectorImpl<ValueDecl *>::iterator I = BlockByCopyDecls.begin(),
-         E = BlockByCopyDecls.end(); I != E; ++I) {
+    for (auto I = BlockByCopyDecls.begin(), E = BlockByCopyDecls.end(); I != E;
+         ++I) {
       if (isObjCType((*I)->getType())) {
         // FIXME: Conform to ABI ([[obj retain] autorelease]).
         FD = SynthBlockInitFunctionDecl((*I)->getName());
@@ -4476,8 +4476,8 @@ Stmt *RewriteObjC::SynthBlockInitExpr(BlockExpr *Exp,
       InitExprs.push_back(Exp);
     }
     // Output all "by ref" declarations.
-    for (SmallVectorImpl<ValueDecl *>::iterator I = BlockByRefDecls.begin(),
-         E = BlockByRefDecls.end(); I != E; ++I) {
+    for (auto I = BlockByRefDecls.begin(), E = BlockByRefDecls.end(); I != E;
+         ++I) {
       ValueDecl *ND = (*I);
       std::string Name(ND->getNameAsString());
       std::string RecName;