When we run into an error parsing or type-checking the left-hand side

of a binary expression, continue on and parse the right-hand side of
the binary expression anyway, but don't call the semantic actions to
type-check. Previously, we would see the error and then, effectively,
skip tokens until the end of the statement. 

The result should be more useful recovery, both in the normal case
(we'll actually see errors beyond the first one in a statement), but
it also helps code completion do a much better job, because we do
"real" code completion on the right-hand side of an invalid binary
expression rather than completing with the recovery completion. For
example, given

  x = p->y

if there is no variable named "x", we can still complete after the p->
as a member expression. Along the recovery path, we would have
completed after the "->" as if we were in an expression context, which
is mostly useless.

llvm-svn: 114225

clang/lib/Parse/ParseExpr.cpp

@@ -177,8 +177,6 @@ static prec::Level getBinOpPrecedence(tok::TokenKind Kind,
 ///
 ExprResult Parser::ParseExpression() {
   ExprResult LHS(ParseAssignmentExpression());
-  if (LHS.isInvalid()) return move(LHS);
-
   return ParseRHSOfBinaryExpression(move(LHS), prec::Comma);
 }
 
@@ -190,8 +188,6 @@ ExprResult Parser::ParseExpression() {
 ExprResult
 Parser::ParseExpressionWithLeadingAt(SourceLocation AtLoc) {
   ExprResult LHS(ParseObjCAtExpression(AtLoc));
-  if (LHS.isInvalid()) return move(LHS);
-
   return ParseRHSOfBinaryExpression(move(LHS), prec::Comma);
 }
 
@@ -206,14 +202,13 @@ Parser::ParseExpressionWithLeadingExtension(SourceLocation ExtLoc) {
     ExtensionRAIIObject O(Diags);
 
     LHS = ParseCastExpression(false);
-    if (LHS.isInvalid()) return move(LHS);
   }
 
-  LHS = Actions.ActOnUnaryOp(getCurScope(), ExtLoc, tok::kw___extension__,
-                             LHS.take());
-  if (LHS.isInvalid()) return move(LHS);
+  if (!LHS.isInvalid())
+    LHS = Actions.ActOnUnaryOp(getCurScope(), ExtLoc, tok::kw___extension__,
+                               LHS.take());
 
-  return ParseRHSOfBinaryExpression(LHS.take(), prec::Comma);
+  return ParseRHSOfBinaryExpression(move(LHS), prec::Comma);
 }
 
 /// ParseAssignmentExpression - Parse an expr that doesn't include commas.
@@ -228,9 +223,7 @@ ExprResult Parser::ParseAssignmentExpression() {
     return ParseThrowExpression();
 
   ExprResult LHS(ParseCastExpression(false));
-  if (LHS.isInvalid()) return move(LHS);
-
-  return ParseRHSOfBinaryExpression(LHS.take(), prec::Assignment);
+  return ParseRHSOfBinaryExpression(move(LHS), prec::Assignment);
 }
 
 /// ParseAssignmentExprWithObjCMessageExprStart - Parse an assignment expression
@@ -251,8 +244,7 @@ Parser::ParseAssignmentExprWithObjCMessageExprStart(SourceLocation LBracLoc,
                                      ReceiverType, ReceiverExpr);
   if (R.isInvalid()) return move(R);
   R = ParsePostfixExpressionSuffix(R.take());
-  if (R.isInvalid()) return move(R);
-  return ParseRHSOfBinaryExpression(R.take(), prec::Assignment);
+  return ParseRHSOfBinaryExpression(R, prec::Assignment);
 }
 
 
@@ -264,9 +256,7 @@ ExprResult Parser::ParseConstantExpression() {
                                                Sema::Unevaluated);
 
   ExprResult LHS(ParseCastExpression(false));
-  if (LHS.isInvalid()) return move(LHS);
-
-  return ParseRHSOfBinaryExpression(LHS.take(), prec::Conditional);
+  return ParseRHSOfBinaryExpression(LHS, prec::Conditional);
 }
 
 /// ParseRHSOfBinaryExpression - Parse a binary expression that starts with
@@ -362,9 +352,10 @@ Parser::ParseRHSOfBinaryExpression(ExprResult LHS, prec::Level MinPrec) {
       RHS = ParseAssignmentExpression();
     else
       RHS = ParseCastExpression(false);
-    if (RHS.isInvalid())
-      return move(RHS);
 
+    if (RHS.isInvalid())
+      LHS = ExprError();
+    
     // Remember the precedence of this operator and get the precedence of the
     // operator immediately to the right of the RHS.
     prec::Level ThisPrec = NextTokPrec;
@@ -384,10 +375,11 @@ Parser::ParseRHSOfBinaryExpression(ExprResult LHS, prec::Level MinPrec) {
       // is okay, to bind exactly as tightly.  For example, compile A=B=C=D as
       // A=(B=(C=D)), where each paren is a level of recursion here.
       // The function takes ownership of the RHS.
-      RHS = ParseRHSOfBinaryExpression(RHS.get(), 
+      RHS = ParseRHSOfBinaryExpression(RHS, 
                             static_cast<prec::Level>(ThisPrec + !isRightAssoc));
+
       if (RHS.isInvalid())
-        return move(RHS);
+        LHS = ExprError();
 
       NextTokPrec = getBinOpPrecedence(Tok.getKind(), GreaterThanIsOperator,
                                        getLang().CPlusPlus0x);
@@ -426,9 +418,9 @@ ExprResult Parser::ParseCastExpression(bool isUnaryExpression,
                                                      ParsedType TypeOfCast) {
   bool NotCastExpr;
   ExprResult Res = ParseCastExpression(isUnaryExpression,
-                                             isAddressOfOperand,
-                                             NotCastExpr,
-                                             TypeOfCast);
+                                       isAddressOfOperand,
+                                       NotCastExpr,
+                                       TypeOfCast);
   if (NotCastExpr)
     Diag(Tok, diag::err_expected_expression);
   return move(Res);

clang/test/FixIt/fixit-unrecoverable.cpp

@@ -6,6 +6,7 @@
 // RUN: %clang_cc1 -fsyntax-only -verify %s
 
 float f(int y) {
-  return static_cst<float>(y); // expected-error{{use of undeclared identifier 'static_cst'; did you mean 'static_cast'?}}
+  return static_cst<float>(y); // expected-error{{use of undeclared identifier 'static_cst'; did you mean 'static_cast'?}} \
+  // expected-error{{for function-style cast or type construction}}
 }
 

clang/test/Index/complete-recovery.m

@@ -7,7 +7,9 @@
 @implementation A
 - (void)method:(int)x {
   A *a = [A method:1];
-  blarg * blah = wibble
+  blarg * blah = wibble;
+  A *a2;
+  z = [a2 method:1];
 }
 @end
 
@@ -23,3 +25,5 @@
 // CHECK-CC2: NotImplemented:{TypedText _Bool}
 // CHECK-CC2: VarDecl:{ResultType A *}{TypedText a}
 // CHECK-CC2: NotImplemented:{TypedText sizeof}{LeftParen (}{Placeholder expression-or-type}{RightParen )}
+// RUN: c-index-test -code-completion-at=%s:12:11 -Xclang -code-completion-patterns %s | FileCheck -check-prefix=CHECK-CC3 %s
+// CHECK-CC3: ObjCInstanceMethodDecl:{ResultType void}{TypedText method:}{Placeholder (int)} (17)

clang/test/SemaCXX/destructor.cpp

@@ -67,7 +67,7 @@ struct Y {
 namespace PR6421 {
   class T; // expected-note{{forward declaration}}
 
-  class QGenericArgument
+  class QGenericArgument // expected-note{{declared here}}
   {
     template<typename U>
     void foo(T t) // expected-error{{variable has incomplete type}}
@@ -76,7 +76,8 @@ namespace PR6421 {
     void disconnect()
     {
       T* t;
-      bob<QGenericArgument>(t); // expected-error{{undeclared identifier 'bob'}}
+      bob<QGenericArgument>(t); // expected-error{{undeclared identifier 'bob'}} \
+      // expected-error{{does not refer to a value}}
     }
   };
 }

clang/test/SemaCXX/elaborated-type-specifier.cpp

@@ -35,7 +35,8 @@ namespace NS {
 }
 
 void test_S5_scope() {
-  S4 *s4; // expected-error{{use of undeclared identifier 'S4'}}
+  S4 *s4; // expected-error{{use of undeclared identifier 'S4'}} \
+  // expected-error{{use of undeclared identifier 's4'}}
 }
 
 int test_funcparam_scope(struct S5 * s5) {

clang/test/SemaObjC/crash-label.m

@@ -7,4 +7,4 @@ Exit:  [nilArgs release]; // expected-error {{use of undeclared identifier}}
 - (NSDictionary *) _setupKernelStandardMode:(NSString *)source { // expected-error 2 {{expected a type}} \
 expected-error {{missing context for method declaration}} \
 expected-note{{to match this '{'}}
-  Exit:   if(_ciKernel && !success ) { // expected-error {{use of undeclared identifier}} // expected-error 2 {{expected}} expected-note{{to match this '{'}}
+  Exit:   if(_ciKernel && !success ) { // expected-error {{use of undeclared identifier}} // expected-error 2 {{expected}} expected-note{{to match this '{'}} expected-error{{use of undeclared identifier 'success'}}

clang/test/SemaTemplate/dependent-base-classes.cpp

@@ -105,7 +105,9 @@ namespace PR6081 {
     void f0(const X & k)
     {
       this->template f1<int>()(k); // expected-error{{'f1' following the 'template' keyword does not refer to a template}} \
-      // FIXME: expected-error{{unqualified-id}}
+      // FIXME: expected-error{{unqualified-id}} \
+      // expected-error{{function-style cast or type construction}} \
+      // expected-error{{expected expression}}
     }
   };
 }