Fix code completion for custom attributes.

Author: DougGregor

include/swift/Parse/Parser.h

@@ -656,7 +656,7 @@ class Parser {
   /// Read tokens until we get to one of the specified tokens, then
   /// return without consuming it.  Because we cannot guarantee that the token
   /// will ever occur, this skips to some likely good stopping point.
-  void skipUntil(tok T1, tok T2 = tok::NUM_TOKENS);
+  ParserStatus skipUntil(tok T1, tok T2 = tok::NUM_TOKENS);
   void skipUntilAnyOperator();
 
   /// Skip until a token that starts with '>', and consume it if found.
@@ -680,7 +680,10 @@ class Parser {
   /// Note: this does \em not match angle brackets ("<" and ">")! These are
   /// matched in the source when they refer to a generic type,
   /// but not when used as comparison operators.
-  void skipSingle();
+  ///
+  /// Returns a parser status that can capture whether a code completion token
+  /// was returned.
+  ParserStatus skipSingle();
 
   /// Skip until the next '#else', '#endif' or until eof.
   void skipUntilConditionalBlockClose();

lib/Parse/ParseDecl.cpp

@@ -2821,7 +2821,8 @@ static PatternBindingInitializer *findAttributeInitContent(
 
 bool Parser::isCustomAttributeArgument() {
   BacktrackingScope backtrack(*this);
-  skipSingle();
+  if (skipSingle().hasCodeCompletion())
+    return true;
 
   // If we have any keyword, identifier, or token that follows a function
   // type's parameter list, this is a parameter list and not an attribute.

lib/Parse/Parser.cpp

@@ -647,49 +647,58 @@ SourceLoc Parser::consumeStartingGreater() {
   return consumeStartingCharacterOfCurrentToken(tok::r_angle);
 }
 
-void Parser::skipSingle() {
+ParserStatus Parser::skipSingle() {
+  ParserStatus status;
   switch (Tok.getKind()) {
   case tok::l_paren:
     consumeToken();
-    skipUntil(tok::r_paren, tok::r_brace);
+    status |= skipUntil(tok::r_paren, tok::r_brace);
     consumeIf(tok::r_paren);
     break;
   case tok::l_brace:
     consumeToken();
-    skipUntil(tok::r_brace);
+    status |= skipUntil(tok::r_brace);
     consumeIf(tok::r_brace);
     break;
   case tok::l_square:
     consumeToken();
-    skipUntil(tok::r_square, tok::r_brace);
+    status |= skipUntil(tok::r_square, tok::r_brace);
     consumeIf(tok::r_square);
     break;
   case tok::pound_if:
   case tok::pound_else:
   case tok::pound_elseif:
     consumeToken();
     // skipUntil also implicitly stops at tok::pound_endif.
-    skipUntil(tok::pound_else, tok::pound_elseif);
+    status |= skipUntil(tok::pound_else, tok::pound_elseif);
 
     if (Tok.isAny(tok::pound_else, tok::pound_elseif))
-      skipSingle();
+      status |= skipSingle();
     else
       consumeIf(tok::pound_endif);
     break;
 
   default:
+    if (Tok.is(tok::code_complete))
+      status.setHasCodeCompletionAndIsError();
     consumeToken();
     break;
   }
+
+  return status;
 }
 
-void Parser::skipUntil(tok T1, tok T2) {
+ParserStatus Parser::skipUntil(tok T1, tok T2) {
+  ParserStatus status;
+
   // tok::NUM_TOKENS is a sentinel that means "don't skip".
-  if (T1 == tok::NUM_TOKENS && T2 == tok::NUM_TOKENS) return;
+  if (T1 == tok::NUM_TOKENS && T2 == tok::NUM_TOKENS) return status;
 
   while (Tok.isNot(T1, T2, tok::eof, tok::pound_endif, tok::pound_else,
                    tok::pound_elseif))
-    skipSingle();
+    status |= skipSingle();
+
+  return status;
 }
 
 void Parser::skipUntilAnyOperator() {

test/Syntax/Outputs/round_trip_parse_gen.swift.withkinds

@@ -145,7 +145,7 @@ typealias G <TypeInitializerClause>= <FunctionType>(<TupleTypeElement>a x: <Simp
 typealias H <TypeInitializerClause>= <FunctionType>() rethrows -> <TupleType>()</TupleType></FunctionType></TypeInitializerClause></TypealiasDecl><TypealiasDecl>
 typealias I <TypeInitializerClause>= <FunctionType>(<TupleTypeElement><CompositionType><CompositionTypeElement><SimpleTypeIdentifier>A </SimpleTypeIdentifier>& </CompositionTypeElement><CompositionTypeElement><SimpleTypeIdentifier>B<GenericArgumentClause><<GenericArgument><SimpleTypeIdentifier>C</SimpleTypeIdentifier></GenericArgument>></GenericArgumentClause></SimpleTypeIdentifier></CompositionTypeElement></CompositionType></TupleTypeElement>) -> <CompositionType><CompositionTypeElement><SimpleTypeIdentifier>C </SimpleTypeIdentifier>& </CompositionTypeElement><CompositionTypeElement><SimpleTypeIdentifier>D</SimpleTypeIdentifier></CompositionTypeElement></CompositionType></FunctionType></TypeInitializerClause></TypealiasDecl><TypealiasDecl>
 typealias J <TypeInitializerClause>= <AttributedType>inout <Attribute>@autoclosure </Attribute><FunctionType>() -> <SimpleTypeIdentifier>Int</SimpleTypeIdentifier></FunctionType></AttributedType></TypeInitializerClause></TypealiasDecl><TypealiasDecl>
-typealias K <TypeInitializerClause>= <FunctionType>(<TupleTypeElement><Attribute>@invalidAttr </Attribute><SimpleTypeIdentifier>Int</SimpleTypeIdentifier>, </TupleTypeElement><TupleTypeElement><AttributedType>inout <SimpleTypeIdentifier>Int</SimpleTypeIdentifier></AttributedType>, </TupleTypeElement><TupleTypeElement><AttributedType>__shared <SimpleTypeIdentifier>Int</SimpleTypeIdentifier></AttributedType>, </TupleTypeElement><TupleTypeElement><AttributedType>__owned <SimpleTypeIdentifier>Int</SimpleTypeIdentifier></AttributedType></TupleTypeElement>) -> <TupleType>()</TupleType></FunctionType></TypeInitializerClause></TypealiasDecl><TypealiasDecl><Attribute>
+typealias K <TypeInitializerClause>= <FunctionType>(<TupleTypeElement><AttributedType><CustomAttribute>@<SimpleTypeIdentifier>invalidAttr </SimpleTypeIdentifier></CustomAttribute><SimpleTypeIdentifier>Int</SimpleTypeIdentifier></AttributedType>, </TupleTypeElement><TupleTypeElement><AttributedType>inout <SimpleTypeIdentifier>Int</SimpleTypeIdentifier></AttributedType>, </TupleTypeElement><TupleTypeElement><AttributedType>__shared <SimpleTypeIdentifier>Int</SimpleTypeIdentifier></AttributedType>, </TupleTypeElement><TupleTypeElement><AttributedType>__owned <SimpleTypeIdentifier>Int</SimpleTypeIdentifier></AttributedType></TupleTypeElement>) -> <TupleType>()</TupleType></FunctionType></TypeInitializerClause></TypealiasDecl><TypealiasDecl><Attribute>
 
 @objc </Attribute><DeclModifier>private </DeclModifier>typealias T<GenericParameterClause><<GenericParameter>a,</GenericParameter><GenericParameter>b</GenericParameter>> </GenericParameterClause><TypeInitializerClause>= <SimpleTypeIdentifier>Int</SimpleTypeIdentifier></TypeInitializerClause></TypealiasDecl><TypealiasDecl><Attribute>
 @objc </Attribute><DeclModifier>private </DeclModifier>typealias T<GenericParameterClause><<GenericParameter>a,</GenericParameter><GenericParameter>b</GenericParameter>></GenericParameterClause></TypealiasDecl><ClassDecl>