Don't try to extract import to a method (#18025)

Author: Andy

src/compiler/utilities.ts

@@ -4951,54 +4951,60 @@ namespace ts {
             || kind === SyntaxKind.NoSubstitutionTemplateLiteral;
     }
 
-    function isLeftHandSideExpressionKind(kind: SyntaxKind): boolean {
-        return kind === SyntaxKind.PropertyAccessExpression
-            || kind === SyntaxKind.ElementAccessExpression
-            || kind === SyntaxKind.NewExpression
-            || kind === SyntaxKind.CallExpression
-            || kind === SyntaxKind.JsxElement
-            || kind === SyntaxKind.JsxSelfClosingElement
-            || kind === SyntaxKind.TaggedTemplateExpression
-            || kind === SyntaxKind.ArrayLiteralExpression
-            || kind === SyntaxKind.ParenthesizedExpression
-            || kind === SyntaxKind.ObjectLiteralExpression
-            || kind === SyntaxKind.ClassExpression
-            || kind === SyntaxKind.FunctionExpression
-            || kind === SyntaxKind.Identifier
-            || kind === SyntaxKind.RegularExpressionLiteral
-            || kind === SyntaxKind.NumericLiteral
-            || kind === SyntaxKind.StringLiteral
-            || kind === SyntaxKind.NoSubstitutionTemplateLiteral
-            || kind === SyntaxKind.TemplateExpression
-            || kind === SyntaxKind.FalseKeyword
-            || kind === SyntaxKind.NullKeyword
-            || kind === SyntaxKind.ThisKeyword
-            || kind === SyntaxKind.TrueKeyword
-            || kind === SyntaxKind.SuperKeyword
-            || kind === SyntaxKind.ImportKeyword
-            || kind === SyntaxKind.NonNullExpression
-            || kind === SyntaxKind.MetaProperty;
-    }
-
     /* @internal */
     export function isLeftHandSideExpression(node: Node): node is LeftHandSideExpression {
-        return isLeftHandSideExpressionKind(skipPartiallyEmittedExpressions(node).kind);
-    }
-
-    function isUnaryExpressionKind(kind: SyntaxKind): boolean {
-        return kind === SyntaxKind.PrefixUnaryExpression
-            || kind === SyntaxKind.PostfixUnaryExpression
-            || kind === SyntaxKind.DeleteExpression
-            || kind === SyntaxKind.TypeOfExpression
-            || kind === SyntaxKind.VoidExpression
-            || kind === SyntaxKind.AwaitExpression
-            || kind === SyntaxKind.TypeAssertionExpression
-            || isLeftHandSideExpressionKind(kind);
+        switch (node.kind) {
+            case SyntaxKind.PropertyAccessExpression:
+            case SyntaxKind.ElementAccessExpression:
+            case SyntaxKind.NewExpression:
+            case SyntaxKind.CallExpression:
+            case SyntaxKind.JsxElement:
+            case SyntaxKind.JsxSelfClosingElement:
+            case SyntaxKind.TaggedTemplateExpression:
+            case SyntaxKind.ArrayLiteralExpression:
+            case SyntaxKind.ParenthesizedExpression:
+            case SyntaxKind.ObjectLiteralExpression:
+            case SyntaxKind.ClassExpression:
+            case SyntaxKind.FunctionExpression:
+            case SyntaxKind.Identifier:
+            case SyntaxKind.RegularExpressionLiteral:
+            case SyntaxKind.NumericLiteral:
+            case SyntaxKind.StringLiteral:
+            case SyntaxKind.NoSubstitutionTemplateLiteral:
+            case SyntaxKind.TemplateExpression:
+            case SyntaxKind.FalseKeyword:
+            case SyntaxKind.NullKeyword:
+            case SyntaxKind.ThisKeyword:
+            case SyntaxKind.TrueKeyword:
+            case SyntaxKind.SuperKeyword:
+            case SyntaxKind.NonNullExpression:
+            case SyntaxKind.MetaProperty:
+                return true;
+            case SyntaxKind.PartiallyEmittedExpression:
+                return isLeftHandSideExpression((node as PartiallyEmittedExpression).expression);
+            case SyntaxKind.ImportKeyword:
+                return node.parent.kind === SyntaxKind.CallExpression;
+            default:
+                return false;
+        }
     }
 
     /* @internal */
     export function isUnaryExpression(node: Node): node is UnaryExpression {
-        return isUnaryExpressionKind(skipPartiallyEmittedExpressions(node).kind);
+        switch (node.kind) {
+            case SyntaxKind.PrefixUnaryExpression:
+            case SyntaxKind.PostfixUnaryExpression:
+            case SyntaxKind.DeleteExpression:
+            case SyntaxKind.TypeOfExpression:
+            case SyntaxKind.VoidExpression:
+            case SyntaxKind.AwaitExpression:
+            case SyntaxKind.TypeAssertionExpression:
+                return true;
+            case SyntaxKind.PartiallyEmittedExpression:
+                return isUnaryExpression((node as PartiallyEmittedExpression).expression);
+            default:
+                return isLeftHandSideExpression(node);
+        }
     }
 
     /* @internal */
@@ -5014,21 +5020,22 @@ namespace ts {
         }
     }
 
-    function isExpressionKind(kind: SyntaxKind) {
-        return kind === SyntaxKind.ConditionalExpression
-            || kind === SyntaxKind.YieldExpression
-            || kind === SyntaxKind.ArrowFunction
-            || kind === SyntaxKind.BinaryExpression
-            || kind === SyntaxKind.SpreadElement
-            || kind === SyntaxKind.AsExpression
-            || kind === SyntaxKind.OmittedExpression
-            || kind === SyntaxKind.CommaListExpression
-            || isUnaryExpressionKind(kind);
-    }
-
     /* @internal */
     export function isExpression(node: Node): node is Expression {
-        return isExpressionKind(skipPartiallyEmittedExpressions(node).kind);
+        switch (node.kind) {
+            case SyntaxKind.ConditionalExpression:
+            case SyntaxKind.YieldExpression:
+            case SyntaxKind.ArrowFunction:
+            case SyntaxKind.BinaryExpression:
+            case SyntaxKind.SpreadElement:
+            case SyntaxKind.AsExpression:
+            case SyntaxKind.OmittedExpression:
+            case SyntaxKind.CommaListExpression:
+            case SyntaxKind.PartiallyEmittedExpression:
+                return true;
+            default:
+                return isUnaryExpression(node);
+        }
     }
 
     export function isAssertionExpression(node: Node): node is AssertionExpression {

src/services/refactors/extractMethod.ts

@@ -231,18 +231,7 @@ namespace ts.refactor.extractMethod {
             if (errors) {
                 return { errors };
             }
-
-            // If our selection is the expression in an ExpressionStatement, expand
-            // the selection to include the enclosing Statement (this stops us
-            // from trying to care about the return value of the extracted function
-            // and eliminates double semicolon insertion in certain scenarios)
-            const range = isStatement(start)
-                ? [start]
-                : start.parent && start.parent.kind === SyntaxKind.ExpressionStatement
-                    ? [start.parent as Statement]
-                    : start as Expression;
-
-            return { targetRange: { range, facts: rangeFacts, declarations } };
+            return { targetRange: { range: getStatementOrExpressionRange(start), facts: rangeFacts, declarations } };
         }
 
         function createErrorResult(sourceFile: SourceFile, start: number, length: number, message: DiagnosticMessage): RangeToExtract {
@@ -459,6 +448,20 @@ namespace ts.refactor.extractMethod {
         }
     }
 
+    function getStatementOrExpressionRange(node: Node): Statement[] | Expression {
+        if (isStatement(node)) {
+            return [node];
+        }
+        else if (isExpression(node)) {
+            // If our selection is the expression in an ExpressionStatement, expand
+            // the selection to include the enclosing Statement (this stops us
+            // from trying to care about the return value of the extracted function
+            // and eliminates double semicolon insertion in certain scenarios)
+            return isExpressionStatement(node.parent) ? [node.parent] : node;
+        }
+        return undefined;
+    }
+
     function isValidExtractionTarget(node: Node): node is Scope {
         // Note that we don't use isFunctionLike because we don't want to put the extracted closure *inside* a method
         return (node.kind === SyntaxKind.FunctionDeclaration) || isSourceFile(node) || isModuleBlock(node) || isClassLike(node);

tests/cases/fourslash/extract-method-not-for-import.ts

@@ -0,0 +1,10 @@
+/// <reference path='fourslash.ts' />
+
+// @Filename: /a.ts
+////i/**/mport _ from "./b";
+
+// @Filename: /b.ts
+////export default function f() {}
+
+goTo.marker("");
+verify.not.refactorAvailable('Extract Method');