[CodeCompletion] Fallback to nominal member completion after trailing closure

After trailing closure, we perform "Labeled trailing closure" completion
and fall back to other completion depending on the position.

If the completion happens at a newline position, it used to fallback to
global expression completion, but in type context, we should do override
completion instead.

Also, we didn't use to propagate 'hasCodeCompletion()' status properly.

rdar://problem/64650782

Author: rintaro

lib/IDE/CodeCompletion.cpp

@@ -6158,15 +6158,29 @@ void CodeCompletionCallbacksImpl::doneParsing() {
       if (IsAtStartOfLine) {
         //   foo() {}
         //   <HERE>
-        // Global completion.
+
         auto &Sink = CompletionContext.getResultSink();
-        addDeclKeywords(Sink);
-        addStmtKeywords(Sink, MaybeFuncBody);
-        addSuperKeyword(Sink);
-        addLetVarKeywords(Sink);
-        addExprKeywords(Sink);
-        addAnyTypeKeyword(Sink, CurDeclContext->getASTContext().TheAnyType);
-        DoPostfixExprBeginning();
+        if (isa<Initializer>(CurDeclContext))
+          CurDeclContext = CurDeclContext->getParent();
+
+        if (CurDeclContext->isTypeContext()) {
+          // Override completion (CompletionKind::NominalMemberBeginning).
+          addDeclKeywords(Sink);
+          addLetVarKeywords(Sink);
+          SmallVector<StringRef, 0> ParsedKeywords;
+          CompletionOverrideLookup OverrideLookup(Sink, Context, CurDeclContext,
+                                                  ParsedKeywords, SourceLoc());
+          OverrideLookup.getOverrideCompletions(SourceLoc());
+        } else {
+          // Global completion (CompletionKind::PostfixExprBeginning).
+          addDeclKeywords(Sink);
+          addStmtKeywords(Sink, MaybeFuncBody);
+          addSuperKeyword(Sink);
+          addLetVarKeywords(Sink);
+          addExprKeywords(Sink);
+          addAnyTypeKeyword(Sink, Context.TheAnyType);
+          DoPostfixExprBeginning();
+        }
       } else {
         //   foo() {} <HERE>
         // Member completion.

lib/Parse/ParseExpr.cpp

@@ -3225,7 +3225,7 @@ Parser::parseTrailingClosures(bool isExprBasic, SourceRange calleeRange,
       if (CodeCompletion)
         CodeCompletion->completeLabeledTrailingClosure(CCExpr, Tok.isAtStartOfLine());
       consumeToken(tok::code_complete);
-      result.hasCodeCompletion();
+      result.setHasCodeCompletion();
       closures.push_back({Identifier(), SourceLoc(), CCExpr});
       continue;
     }

test/IDE/complete_multiple_trailingclosure.swift

@@ -15,6 +15,8 @@
 // RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=INIT_REQUIRED_NEWLINE_3 | %FileCheck %s -check-prefix=INIT_REQUIRED_NEWLINE_3
 // RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=INIT_FALLBACK_1 | %FileCheck %s -check-prefix=INIT_FALLBACK
 // RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=INIT_FALLBACK_2 | %FileCheck %s -check-prefix=INIT_FALLBACK
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=MEMBERDECL_SAMELINE | %FileCheck %s -check-prefix=MEMBERDECL_SAMELINE
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=MEMBERDECL_NEWLINE | %FileCheck %s -check-prefix=MEMBERDECL_NEWLINE
 
 func globalFunc1(fn1: () -> Int, fn2: () -> String) {}
 func testGlobalFunc() {
@@ -207,3 +209,28 @@ func testFallbackPostfix() {
     1
   } #^INIT_FALLBACK_2^#
 }
+
+protocol P {
+  func foo()
+}
+struct TestNominalMember: P {
+  var value = MyStruct().method1 { 1 } #^MEMBERDECL_SAMELINE^#
+  #^MEMBERDECL_NEWLINE^#
+
+// MEMBERDECL_SAMELINE: Begin completions, 4 items
+// MEMBERDECL_SAMELINE-DAG: Pattern/ExprSpecific:               {#fn2: (() -> String)? {() -> String in|}#}[#(() -> String)?#]; name=fn2: (() -> String)?
+// MEMBERDECL_SAMELINE-DAG: Decl[InstanceMethod]/CurrNominal:   .enumFunc()[#Void#]; name=enumFunc()
+// MEMBERDECL_SAMELINE-DAG: Decl[InfixOperatorFunction]/OtherModule[Swift]/IsSystem: [' ']+ {#SimpleEnum#}[#SimpleEnum#]; name=+ SimpleEnum
+// MEMBERDECL_SAMELINE-DAG: Keyword[self]/CurrNominal:          .self[#SimpleEnum#]; name=self
+// MEMBERDECL_SAMELINE: End completions
+
+// MEMBERDECL_NEWLINE: Begin completions
+// MEMBERDECL_NEWLINE-DAG: Pattern/ExprSpecific:               {#fn2: (() -> String)? {() -> String in|}#}[#(() -> String)?#]; name=fn2: (() -> String)?
+// MEMBERDECL_NEWLINE-DAG: Keyword[enum]/None:                 enum; name=enum
+// MEMBERDECL_NEWLINE-DAG: Keyword[func]/None:                 func; name=func
+// MEMBERDECL_NEWLINE-DAG: Keyword[private]/None:              private; name=private
+// MEMBERDECL_NEWLINE-DAG: Keyword/None:                       lazy; name=lazy
+// MEMBERDECL_NEWLINE-DAG: Keyword[var]/None:                  var; name=var
+// MEMBERDECL_NEWLINE-DAG: Decl[InstanceMethod]/Super:         func foo() {|}; name=foo()
+// MEMBERDECL_NEWLINE: End completions
+}