[code-completion] Remove special handling for completion on the RHS of an assignment

This simplifies the code and prevents an assertion failure this code was
hitting computing the type relations between the result types and what it
determined as the expected type.

Resolves rdar://problem/53958454

Author: Nathan Hawes

include/swift/IDE/CodeCompletion.h

@@ -498,7 +498,6 @@ enum class CompletionKind {
   AttributeBegin,
   AttributeDeclParen,
   PoundAvailablePlatform,
-  AssignmentRHS,
   CallArg,
   ReturnStmtExpr,
   YieldStmtExpr,

include/swift/Parse/CodeCompletionCallbacks.h

@@ -200,8 +200,6 @@ class CodeCompletionCallbacks {
   virtual void completeUnresolvedMember(CodeCompletionExpr *E,
                                         SourceLoc DotLoc) {};
 
-  virtual void completeAssignmentRHS(AssignExpr *E) {};
-
   virtual void completeCallArg(CodeCompletionExpr *E, bool isFirst) {};
 
   virtual void completeReturnStmt(CodeCompletionExpr *E) {};

lib/IDE/CodeCompletion.cpp

@@ -1213,7 +1213,6 @@ class CodeCompletionCallbacksImpl : public CodeCompletionCallbacks {
   std::vector<RequestedCachedModule> RequestedModules;
   CodeCompletionConsumer &Consumer;
   CodeCompletionExpr *CodeCompleteTokenExpr = nullptr;
-  AssignExpr *AssignmentExpr;
   CompletionKind Kind = CompletionKind::None;
   Expr *ParsedExpr = nullptr;
   SourceLoc DotLoc;
@@ -1367,7 +1366,6 @@ class CodeCompletionCallbacksImpl : public CodeCompletionCallbacks {
   void completeImportDecl(std::vector<std::pair<Identifier, SourceLoc>> &Path) override;
   void completeUnresolvedMember(CodeCompletionExpr *E,
                                 SourceLoc DotLoc) override;
-  void completeAssignmentRHS(AssignExpr *E) override;
   void completeCallArg(CodeCompletionExpr *E, bool isFirst) override;
   void completeReturnStmt(CodeCompletionExpr *E) override;
   void completeYieldStmt(CodeCompletionExpr *E,
@@ -4671,13 +4669,6 @@ void CodeCompletionCallbacksImpl::completeUnresolvedMember(CodeCompletionExpr *E
   this->DotLoc = DotLoc;
 }
 
-void CodeCompletionCallbacksImpl::completeAssignmentRHS(AssignExpr *E) {
-  AssignmentExpr = E;
-  ParsedExpr = E->getDest();
-  CurDeclContext = P.CurDeclContext;
-  Kind = CompletionKind::AssignmentRHS;
-}
-
 void CodeCompletionCallbacksImpl::completeCallArg(CodeCompletionExpr *E,
                                                   bool isFirst) {
   CurDeclContext = P.CurDeclContext;
@@ -4906,7 +4897,6 @@ void CodeCompletionCallbacksImpl::addKeywords(CodeCompletionResultSink &Sink,
     addDeclKeywords(Sink);
     addStmtKeywords(Sink, MaybeFuncBody);
     LLVM_FALLTHROUGH;
-  case CompletionKind::AssignmentRHS:
   case CompletionKind::ReturnStmtExpr:
   case CompletionKind::YieldStmtExpr:
   case CompletionKind::PostfixExprBeginning:
@@ -5373,14 +5363,6 @@ void CodeCompletionCallbacksImpl::doneParsing() {
     Lookup.getUnresolvedMemberCompletions(ContextInfo.getPossibleTypes());
     break;
   }
-  case CompletionKind::AssignmentRHS : {
-    SourceLoc Loc = P.Context.SourceMgr.getCodeCompletionLoc();
-    if (auto destType = ParsedExpr->getType())
-      Lookup.setExpectedTypes(destType->getRValueType(),
-                              /*isSingleExpressionBody*/ false);
-    Lookup.getValueCompletionsInDeclContext(Loc, DefaultFilter);
-    break;
-  }
   case CompletionKind::CallArg : {
     ExprContextInfo ContextInfo(CurDeclContext, CodeCompleteTokenExpr);
 

lib/Parse/ParseExpr.cpp

@@ -279,28 +279,6 @@ ParserResult<Expr> Parser::parseExprSequence(Diag<> Message,
       auto *assign = new (Context) AssignExpr(equalsLoc);
       SequencedExprs.push_back(assign);
       Message = diag::expected_expr_assignment;
-      if (Tok.is(tok::code_complete)) {
-        if (CodeCompletion) {
-          auto RHS = new (Context) ErrorExpr(
-            SourceRange(Tok.getRange().getStart(), Tok.getRange().getEnd()));
-          assign->setSrc(RHS);
-          SequencedExprs.pop_back();
-          assign->setDest(SequencedExprs.back());
-          SequencedExprs.pop_back();
-          SequencedExprs.push_back(assign);
-          CodeCompletion->completeAssignmentRHS(assign);
-        }
-        consumeToken();
-        if (!SequencedExprs.empty() && (SequencedExprs.size() & 1) == 0) {
-          // Make sure we have odd number of sequence exprs.
-          SequencedExprs.pop_back();
-        }
-        auto Result = SequencedExprs.size() == 1 ?
-          makeParserResult(SequencedExprs[0]):
-          makeParserResult(SequenceExpr::create(Context, SequencedExprs));
-        Result.setHasCodeCompletion();
-        return Result;
-      }
       break;
     }
 

test/IDE/complete_associated_types.swift

@@ -20,6 +20,15 @@
 // RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=BROKEN_CONFORMANCE_1 > %t.types.txt
 // RUN: %FileCheck %s -check-prefix=BROKEN_CONFORMANCE_1 < %t.types.txt
 
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=BROKEN_CONFORMANCE_UNASSIGNABLE > %t.types.txt
+// RUN: %FileCheck %s -check-prefix=BROKEN_CONFORMANCE_UNASSIGNABLE < %t.types.txt
+
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=BROKEN_CONFORMANCE_UNASSIGNABLE_2 > %t.types.txt
+// RUN: %FileCheck %s -check-prefix=BROKEN_CONFORMANCE_UNASSIGNABLE < %t.types.txt
+
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=BROKEN_CONFORMANCE_ASSIGNABLE > %t.types.txt
+// RUN: %FileCheck %s -check-prefix=BROKEN_CONFORMANCE_ASSIGNABLE < %t.types.txt
+
 // FIXME: extensions that introduce conformances?
 
 protocol FooBaseProtocolWithAssociatedTypes {
@@ -300,3 +309,44 @@ func testBrokenConformances1() {
 // BROKEN_CONFORMANCE_1-DAG: Decl[InstanceMethod]/Super:         deduceFooBaseC({#(self): StructWithBrokenConformance#})[#() -> StructWithBrokenConformance.FooBaseDeducedTypeC#]{{; name=.+$}}
 // BROKEN_CONFORMANCE_1-DAG: Decl[InstanceMethod]/Super:         deduceFooBaseD({#(self): StructWithBrokenConformance#})[#() -> StructWithBrokenConformance.FooBaseDeducedTypeD#]{{; name=.+$}}
 // BROKEN_CONFORMANCE_1: End completions
+
+
+protocol MyProto {
+    associatedtype Element
+}
+
+extension MyProto {
+    var matches: (Int, (Int, Int)) { fatalError() }
+    func first() -> Element {
+        fatalError()
+    }
+}
+
+// Does not conform - Element not specified
+struct A<T>: MyProto {
+    func foo() {
+        self.first = #^BROKEN_CONFORMANCE_UNASSIGNABLE^#
+    }
+
+    func foo2() {
+      var (a, b): (Int, Int)
+      let exact = (1, (2, 4))
+      (a, (b, self.first)) = #^BROKEN_CONFORMANCE_UNASSIGNABLE_2^#
+    }
+
+    func foo3() {
+      var (a, b, c): (Int, Int, Int)
+      let exact = (1, (2, 4))
+      (a, (b, c)) = #^BROKEN_CONFORMANCE_ASSIGNABLE^#
+    }
+}
+// BROKEN_CONFORMANCE_UNASSIGNABLE: Begin completions
+// BROKEN_CONFORMANCE_UNASSIGNABLE-NOT: TypeRelation
+// BROKEN_CONFORMANCE_UNASSIGNABLE: Decl[InstanceMethod]/Super:         first()[#MyProto.Element#]; name=first()
+// BROKEN_CONFORMANCE_UNASSIGNABLE-NOT: TypeRelation
+// BROKEN_CONFORMANCE_UNASSIGNABLE: End completions
+
+// BROKEN_CONFORMANCE_ASSIGNABLE: Begin completions
+// BROKEN_CONFORMANCE_ASSIGNABLE-DAG: Decl[LocalVar]/Local/TypeRelation[Identical]: exact[#(Int, (Int, Int))#]; name=exact
+// BROKEN_CONFORMANCE_ASSIGNABLE-DAG: Decl[InstanceVar]/Super/TypeRelation[Identical]: matches[#(Int, (Int, Int))#]; name=matches
+// BROKEN_CONFORMANCE_ASSIGNABLE: End completions

tools/SourceKit/lib/SwiftLang/CodeCompletionOrganizer.cpp

@@ -176,7 +176,6 @@ bool SourceKit::CodeCompletion::addCustomCompletions(
       }
       break;
     case CompletionKind::PostfixExprBeginning:
-    case CompletionKind::AssignmentRHS:
     case CompletionKind::CallArg:
     case CompletionKind::ReturnStmtExpr:
     case CompletionKind::YieldStmtExpr: