final edits, needs better docstring in expectedAssignStmtTypes

gopls/internal/golang/completion/completion.go

@@ -2303,7 +2303,10 @@ Nodes:
 				break Nodes
 			}
 		case *ast.AssignStmt:
-			return expectedAssignStmtCandidate(c, node, inf)
+			objType, assignees := expectedAssignStmtTypes(c, node)
+			inf.objType = objType
+			inf.assignees = assignees
+			return inf
 		case *ast.ValueSpec:
 			inf.objType = expectedValueSpecType(c, node)
 			return
@@ -2506,12 +2509,11 @@ func inferExpectedResultTypes(c *completer, callNodeIdx int) []types.Type {
 			expectedResults = append(expectedResults, expectedCompositeLiteralType(enclosingCompositeLiteral, c.pos))
 		}
 	case *ast.AssignStmt:
-		inf := expectedAssignStmtCandidate(c, node, candidateInference{})
-		if len(inf.assignees) > 0 {
-			expectedResults = make([]types.Type, len(inf.assignees))
-			copy(expectedResults, inf.assignees)
-		} else if inf.objType != nil {
-			expectedResults = append(expectedResults, inf.objType)
+		objType, assignees := expectedAssignStmtTypes(c, node)
+		if len(assignees) > 0 {
+			return assignees
+		} else if objType != nil {
+			expectedResults = append(expectedResults, objType)
 		}
 	case *ast.ValueSpec:
 		if resultType := expectedValueSpecType(c, node); resultType != nil {
@@ -2576,34 +2578,33 @@ func expectedValueSpecType(c *completer, node *ast.ValueSpec) types.Type {
 	return nil
 }
 
-// expectedAssignStmtCandidate returns information about the expected candidate
-// for a AssignStmt at the query position.
-func expectedAssignStmtCandidate(c *completer, node *ast.AssignStmt, inf candidateInference) candidateInference {
+// expectedAssignStmtTypes returns the inference objType and assignees for the assignment.
+func expectedAssignStmtTypes(c *completer, node *ast.AssignStmt) (objType types.Type, assignees []types.Type) {
 	// Only rank completions if you are on the right side of the token.
 	if c.pos > node.TokPos {
 		i := exprAtPos(c.pos, node.Rhs)
 		if i >= len(node.Lhs) {
 			i = len(node.Lhs) - 1
 		}
 		if tv, ok := c.pkg.TypesInfo().Types[node.Lhs[i]]; ok {
-			inf.objType = tv.Type
+			objType = tv.Type
 		}
 
 		// If we have a single expression on the RHS, record the LHS
 		// assignees so we can favor multi-return function calls with
 		// matching result values.
 		if len(node.Rhs) <= 1 {
 			for _, lhs := range node.Lhs {
-				inf.assignees = append(inf.assignees, c.pkg.TypesInfo().TypeOf(lhs))
+				assignees = append(assignees, c.pkg.TypesInfo().TypeOf(lhs))
 			}
 		} else {
 			// Otherwise, record our single assignee, even if its type is
 			// not available. We use this info to downrank functions
 			// with the wrong number of result values.
-			inf.assignees = append(inf.assignees, c.pkg.TypesInfo().TypeOf(node.Lhs[i]))
+			assignees = append(assignees, c.pkg.TypesInfo().TypeOf(node.Lhs[i]))
 		}
 	}
-	return inf
+	return objType, assignees
 }
 
 // expectedReturnStmtType returns the expected type of a return statement.