Add code fix for importsNotUsedAsValues error (#37468)

Author: andrewbranch

src/services/codefixes/convertToTypeOnlyImport.ts

@@ -0,0 +1,52 @@
+/* @internal */
+namespace ts.codefix {
+    const errorCodes = [Diagnostics.This_import_is_never_used_as_a_value_and_must_use_import_type_because_the_importsNotUsedAsValues_is_set_to_error.code];
+    const fixId = "convertToTypeOnlyImport";
+    registerCodeFix({
+        errorCodes,
+        getCodeActions: context => {
+            const changes = textChanges.ChangeTracker.with(context, t => {
+                const importDeclaration = getImportDeclarationForDiagnosticSpan(context.span, context.sourceFile);
+                fixSingleImportDeclaration(t, importDeclaration, context);
+            });
+            if (changes.length) {
+                return [createCodeFixAction(fixId, changes, Diagnostics.Convert_to_type_only_import, fixId, Diagnostics.Convert_all_imports_not_used_as_a_value_to_type_only_imports)];
+            }
+        },
+        fixIds: [fixId],
+        getAllCodeActions: context => {
+            return codeFixAll(context, errorCodes, (changes, diag) => {
+                const importDeclaration = getImportDeclarationForDiagnosticSpan(diag, context.sourceFile);
+                fixSingleImportDeclaration(changes, importDeclaration, context);
+            });
+        }
+    });
+
+    function getImportDeclarationForDiagnosticSpan(span: TextSpan, sourceFile: SourceFile) {
+        return tryCast(getTokenAtPosition(sourceFile, span.start).parent, isImportDeclaration);
+    }
+
+    function fixSingleImportDeclaration(changes: textChanges.ChangeTracker, importDeclaration: ImportDeclaration | undefined, context: CodeFixContextBase) {
+        if (!importDeclaration?.importClause) {
+            return;
+        }
+
+        const { importClause } = importDeclaration;
+        // `changes.insertModifierBefore` produces a range that might overlap further changes
+        changes.insertText(context.sourceFile, importDeclaration.getStart() + "import".length, " type");
+
+        // `import type foo, { Bar }` is not allowed, so move `foo` to new declaration
+        if (importClause.name && importClause.namedBindings) {
+            changes.deleteNodeRangeExcludingEnd(context.sourceFile, importClause.name, importDeclaration.importClause.namedBindings);
+            changes.insertNodeBefore(context.sourceFile, importDeclaration, updateImportDeclaration(
+                importDeclaration,
+                /*decorators*/ undefined,
+                /*modifiers*/ undefined,
+                createImportClause(
+                    importClause.name,
+                    /*namedBindings*/ undefined,
+                    /*isTypeOnly*/ true),
+                importDeclaration.moduleSpecifier));
+        }
+    }
+}

src/services/tsconfig.json

@@ -60,6 +60,7 @@
         "codefixes/convertToEs6Module.ts",
         "codefixes/correctQualifiedNameToIndexedAccessType.ts",
         "codefixes/convertToTypeOnlyExport.ts",
+        "codefixes/convertToTypeOnlyImport.ts",
         "codefixes/fixClassIncorrectlyImplementsInterface.ts",
         "codefixes/importFixes.ts",
         "codefixes/fixImplicitThis.ts",

tests/cases/fourslash/codeFixConvertToTypeOnlyImport1.ts

@@ -0,0 +1,32 @@
+/// <reference path="fourslash.ts" />
+
+// @importsNotUsedAsValues: error
+
+// @Filename: exports.ts
+////export default class A {}
+////export class B {}
+////export class C {}
+
+// @Filename: imports.ts
+////import {
+////  B,
+////  C,
+////} from './exports';
+////
+////declare const b: B;
+////declare const c: C;
+////console.log(b, c);
+
+goTo.file("imports.ts");
+verify.codeFix({
+  index: 0,
+  description: ts.Diagnostics.Convert_to_type_only_import.message,
+  newFileContent: `import type {
+  B,
+  C,
+} from './exports';
+
+declare const b: B;
+declare const c: C;
+console.log(b, c);`
+});

tests/cases/fourslash/codeFixConvertToTypeOnlyImport2.ts

@@ -0,0 +1,29 @@
+/// <reference path="fourslash.ts" />
+
+// @importsNotUsedAsValues: error
+
+// @Filename: exports.ts
+////export default class A {}
+////export class B {}
+////export class C {}
+
+// @Filename: imports.ts
+////import A, { B, C } from './exports';
+////
+////declare const a: A;
+////declare const b: B;
+////declare const c: C;
+////console.log(a, b, c);
+
+goTo.file("imports.ts");
+verify.codeFix({
+  index: 0,
+  description: ts.Diagnostics.Convert_to_type_only_import.message,
+  newFileContent: `import type A from './exports';
+import type { B, C } from './exports';
+
+declare const a: A;
+declare const b: B;
+declare const c: C;
+console.log(a, b, c);`
+});

tests/cases/fourslash/codeFixConvertToTypeOnlyImport3.ts

@@ -0,0 +1,41 @@
+/// <reference path="fourslash.ts" />
+
+// @importsNotUsedAsValues: error
+
+// @Filename: exports1.ts
+////export default class A {}
+////export class B {}
+////export class C {}
+
+// @Filename: exports2.ts
+////export default class D {}
+////export class E {}
+////export class F {}
+
+// @Filename: imports.ts
+////import A, { B, C } from './exports1';
+////import D, * as others from "./exports2";
+////
+////declare const a: A;
+////declare const b: B;
+////declare const c: C;
+////declare const d: D;
+////declare const o: typeof others;
+////console.log(a, b, c, d, o);
+
+goTo.file("imports.ts");
+verify.codeFixAll({
+  fixId: "convertToTypeOnlyImport",
+  fixAllDescription: ts.Diagnostics.Convert_all_imports_not_used_as_a_value_to_type_only_imports.message,
+  newFileContent: `import type A from './exports1';
+import type { B, C } from './exports1';
+import type D from "./exports2";
+import type * as others from "./exports2";
+
+declare const a: A;
+declare const b: B;
+declare const c: C;
+declare const d: D;
+declare const o: typeof others;
+console.log(a, b, c, d, o);`
+});