[CodeCompletion] Fix completion in string literal interpolation at top-level

Mostly this was just returning the ParserStatus bits that we got from
parseExprList from parseExprStringLiteral. The rest was just cleaning up
places that didn't handle EOF very well, which is important here because
the code completion token is buried in the string literal, so the
primary lexer will walk past it.

rdar://problem/17101944

Author: benlangmuir

include/swift/Parse/Parser.h

@@ -1110,7 +1110,7 @@ class Parser {
   ParserResult<Expr> parseExprSelector();
   ParserResult<Expr> parseExprSuper();
   ParserResult<Expr> parseExprConfiguration();
-  Expr *parseExprStringLiteral();
+  ParserResult<Expr> parseExprStringLiteral();
 
   /// If the token is an escaped identifier being used as an argument
   /// label, but doesn't need to be, diagnose it.

lib/Parse/ParseDecl.cpp

@@ -1829,7 +1829,7 @@ void Parser::consumeDecl(ParserPosition BeginParserPosition,
   backtrackToPosition(BeginParserPosition);
   SourceLoc BeginLoc = Tok.getLoc();
   // Consume tokens up to code completion token.
-  while (Tok.isNot(tok::code_complete))
+  while (Tok.isNot(tok::code_complete, tok::eof))
     consumeToken();
 
   // Consume the code completion token, if there is one.

lib/Parse/ParseExpr.cpp

@@ -865,7 +865,7 @@ ParserResult<Expr> Parser::parseExprPostfix(Diag<> ID, bool isExprBasic) {
     SWIFT_FALLTHROUGH;
 
   case tok::string_literal:  // "foo"
-    Result = makeParserResult(parseExprStringLiteral());
+    Result = parseExprStringLiteral();
     break;
 
   case tok::kw_nil:
@@ -1383,18 +1383,19 @@ createStringLiteralExprFromSegment(ASTContext &Ctx,
 
 ///   expr-literal:
 ///     string_literal
-Expr *Parser::parseExprStringLiteral() {
+ParserResult<Expr> Parser::parseExprStringLiteral() {
   SmallVector<Lexer::StringSegment, 1> Segments;
   L->getStringLiteralSegments(Tok, Segments);
   SourceLoc Loc = consumeToken();
 
   // The simple case: just a single literal segment.
   if (Segments.size() == 1 &&
       Segments.front().Kind == Lexer::StringSegment::Literal) {
-    return createStringLiteralExprFromSegment(Context, L, Segments.front(),
-                                              Loc);
+    return makeParserResult(
+        createStringLiteralExprFromSegment(Context, L, Segments.front(), Loc));
   }
-    
+
+  ParserStatus Status;
   SmallVector<Expr*, 4> Exprs;
   bool First = true;
   for (auto Segment : Segments) {
@@ -1436,6 +1437,7 @@ Expr *Parser::parseExprStringLiteral() {
       assert(Tok.is(tok::l_paren));
 
       ParserResult<Expr> E = parseExprList(tok::l_paren, tok::r_paren);
+      Status |= E;
       if (E.isNonNull()) {
         Exprs.push_back(E.get());
 
@@ -1449,11 +1451,12 @@ Expr *Parser::parseExprStringLiteral() {
     First = false;
   }
 
-  if (Exprs.empty())
-    return new (Context) ErrorExpr(Loc);
+  if (Exprs.empty()) {
+    Status.setIsParseError();
+    return makeParserResult(Status, new (Context) ErrorExpr(Loc));
+  }
 
-  return new (Context) InterpolatedStringLiteralExpr(Loc,
-                                        Context.AllocateCopy(Exprs));
+  return makeParserResult(Status, new (Context) InterpolatedStringLiteralExpr(Loc, Context.AllocateCopy(Exprs)));
 }
 
 void Parser::diagnoseEscapedArgumentLabel(const Token &tok) {

lib/Parse/ParseStmt.cpp

@@ -168,7 +168,7 @@ void Parser::consumeTopLevelDecl(ParserPosition BeginParserPosition,
   backtrackToPosition(BeginParserPosition);
   SourceLoc BeginLoc = Tok.getLoc();
   // Consume tokens up to code completion token.
-  while (Tok.isNot(tok::code_complete)) {
+  while (Tok.isNot(tok::code_complete, tok::eof)) {
     consumeToken();
   }
   // Consume the code completion token, if there is one.

test/IDE/complete_at_top_level.swift

@@ -118,6 +118,11 @@
 // RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=TOP_LEVEL_GUARD_1 | FileCheck %s -check-prefix=TOP_LEVEL_GUARD
 // RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=TOP_LEVEL_GUARD_2 | FileCheck %s -check-prefix=TOP_LEVEL_GUARD
 
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=STRING_INTERP_1 | FileCheck %s -check-prefix=STRING_INTERP
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=STRING_INTERP_2 | FileCheck %s -check-prefix=STRING_INTERP
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=STRING_INTERP_3 | FileCheck %s -check-prefix=STRING_INTERP
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=STRING_INTERP_4 | FileCheck %s -check-prefix=STRING_INTERP
+
 // Test code completion in top-level code.
 //
 // This test is not meant to test that we can correctly form all kinds of
@@ -420,7 +425,19 @@ func interstitial() {}
 // TOP_LEVEL_GUARD: Decl[LocalVar]/Local: guardedName[#Int#]; name=guardedName
 
 func resyncParserB14() {}
-  
+
+
+"\(#^STRING_INTERP_1^#)"
+"\(1) \(#^STRING_INTERP_2^#) \(2)"
+var stringInterp = "\(#^STRING_INTERP_3^#)"
+_ = "" + "\(#^STRING_INTERP_4^#)" + ""
+// STRING_INTERP: Begin completions
+// STRING_INTERP-DAG: Decl[Struct]/CurrModule: FooStruct[#FooStruct#];
+// STRING_INTERP-DAG: Decl[FreeFunction]/CurrModule: fooFunc1()[#Void#];
+// STRING_INTERP-DAG: Decl[GlobalVar]/Local: fooObject[#FooStruct#];
+// STRING_INTERP: End completions
+func resyncParserC1() {}
+
 
 //
 //===--- DON'T ADD ANY TESTS AFTER THIS LINE.