[SourceKit] Disable labeled trailing closure completion support except code completion

include/swift/Parse/CodeCompletionCallbacks.h

@@ -198,6 +198,10 @@ class CodeCompletionCallbacks {
 
   virtual void completeCallArg(CodeCompletionExpr *E, bool isFirst) {};
 
+  virtual bool canPerformCompleteLabeledTrailingClosure() const {
+    return false;
+  }
+
   virtual void completeLabeledTrailingClosure(CodeCompletionExpr *E,
                                               bool isAtStartOfLine) {};
 

lib/IDE/CodeCompletion.cpp

@@ -1687,6 +1687,10 @@ class CodeCompletionCallbacksImpl : public CodeCompletionCallbacks {
   void completeLabeledTrailingClosure(CodeCompletionExpr *E,
                                       bool isAtStartOfLine) override;
 
+  bool canPerformCompleteLabeledTrailingClosure() const override {
+    return true;
+  }
+
   void completeReturnStmt(CodeCompletionExpr *E) override;
   void completeYieldStmt(CodeCompletionExpr *E,
                          Optional<unsigned> yieldIndex) override;

lib/Parse/ParseExpr.cpp

@@ -3213,6 +3213,13 @@ Parser::parseTrailingClosures(bool isExprBasic, SourceRange calleeRange,
       if (!Tok.is(tok::code_complete))
         break;
 
+      // If the current completion mode doesn't support trailing closure
+      // completion, leave the token here and let "postfix completion" to
+      // handle it.
+      if (CodeCompletion &&
+          !CodeCompletion->canPerformCompleteLabeledTrailingClosure())
+        break;
+
       // foo() {} <token>
       auto CCExpr = new (Context) CodeCompletionExpr(Tok.getLoc());
       if (CodeCompletion)

test/IDE/conforming-methods-afterclosure.swift

@@ -0,0 +1,27 @@
+// RUN: %target-swift-ide-test -conforming-methods -source-filename %s -code-completion-token=AFTER_TRAILINGCLOSURE -module-name MyModule -conforming-methods-expected-types 's:8MyModule7TargetPP' | %FileCheck %s -check-prefix=AFTER_TRAILINGCLOSURE
+
+public protocol TargetP {}
+struct ConcreteP: TargetP {}
+
+public struct MyStruct {
+    init(arg1: Int = 0, fn: () -> Int) {}
+
+    public func returnSomeP -> some TargetP { ConcreteP() }
+    public func returnConcreteP -> ConcreteP { ConcreteP() }
+    public func reutrnInt -> Int { 1 }
+}
+
+func test() {
+    MyStruct {
+        1
+    } #^AFTER_TRAILINGCLOSURE^#
+}
+
+//AFTER_TRAILINGCLOSURE:      -----BEGIN CONFORMING METHOD LIST-----
+//AFTER_TRAILINGCLOSURE-NEXT: - TypeName: MyStruct
+//AFTER_TRAILINGCLOSURE-NEXT: - Members:
+//AFTER_TRAILINGCLOSURE-NEXT:    - Name: returnSomeP()
+//AFTER_TRAILINGCLOSURE-NEXT:      TypeName: some TargetP
+//AFTER_TRAILINGCLOSURE-NEXT:    - Name: returnConcreteP()
+//AFTER_TRAILINGCLOSURE-NEXT:      TypeName: ConcreteP
+//AFTER_TRAILINGCLOSURE-NEXT: -----END CONFORMING METHOD LIST-----