Add codefix for 'convert to unknown' diagnostic

src/compiler/diagnosticMessages.json

@@ -4724,5 +4724,13 @@
     "Generate types for all packages without types": {
         "category": "Message",
         "code": 95068
+    },
+    "Add 'unknown' conversion for non-overlapping types": {
+        "category": "Message",
+        "code": 95069
+    },
+    "Add 'unknown' to all conversions of non-overlapping types": {
+        "category": "Message",
+        "code": 95070
     }
 }

src/services/codefixes/addConvertToUnknownForNonOverlappingTypes.ts

@@ -0,0 +1,23 @@
+/* @internal */
+namespace ts.codefix {
+    const fixId = "addConvertToUnknownForNonOverlappingTypes";
+    const errorCodes = [Diagnostics.Conversion_of_type_0_to_type_1_may_be_a_mistake_because_neither_type_sufficiently_overlaps_with_the_other_If_this_was_intentional_convert_the_expression_to_unknown_first.code];
+    registerCodeFix({
+        errorCodes,
+        getCodeActions: (context) => {
+            const changes = textChanges.ChangeTracker.with(context, t => makeChange(t, context.sourceFile, context.span.start));
+            return [createCodeFixAction(fixId, changes, Diagnostics.Add_unknown_conversion_for_non_overlapping_types, fixId, Diagnostics.Add_unknown_to_all_conversions_of_non_overlapping_types)];
+        },
+        fixIds: [fixId],
+        getAllCodeActions: context => codeFixAll(context, errorCodes, (changes, diag) => makeChange(changes, diag.file, diag.start)),
+    });
+
+    function makeChange(changeTracker: textChanges.ChangeTracker, sourceFile: SourceFile, pos: number) {
+        const token = getTokenAtPosition(sourceFile, pos);
+        const assertion = Debug.assertDefined(findAncestor(token, (n): n is AsExpression | TypeAssertion => isAsExpression(n) || isTypeAssertion(n)));
+        const replacement = isAsExpression(assertion)
+            ? createAsExpression(assertion.expression, createKeywordTypeNode(SyntaxKind.UnknownKeyword))
+            : createTypeAssertion(createKeywordTypeNode(SyntaxKind.UnknownKeyword), assertion.expression);
+        changeTracker.replaceNode(sourceFile, assertion.expression, replacement);
+    }
+}

src/services/tsconfig.json

@@ -43,6 +43,7 @@
         "textChanges.ts",
         "codeFixProvider.ts",
         "refactorProvider.ts",
+        "codefixes/addConvertToUnknownForNonOverlappingTypes.ts",
         "codefixes/addMissingInvocationForDecorator.ts",
         "codefixes/annotateWithTypeFromJSDoc.ts",
         "codefixes/convertFunctionToEs6Class.ts",

tests/cases/fourslash/codeFixAddConvertToUnknownForNonOverlappingTypes1.ts

@@ -0,0 +1,8 @@
+/// <reference path='fourslash.ts' />
+
+////0 as string
+
+verify.codeFix({
+    description: "Add 'unknown' conversion for non-overlapping types",
+    newFileContent: `0 as unknown as string`
+});

tests/cases/fourslash/codeFixAddConvertToUnknownForNonOverlappingTypes2.ts

@@ -0,0 +1,8 @@
+/// <reference path='fourslash.ts' />
+
+////0 * (4 + 3) / 100 as string
+
+verify.codeFix({
+    description: "Add 'unknown' conversion for non-overlapping types",
+    newFileContent: `0 * (4 + 3) / 100 as unknown as string`
+});

tests/cases/fourslash/codeFixAddConvertToUnknownForNonOverlappingTypes3.ts

@@ -0,0 +1,8 @@
+/// <reference path='fourslash.ts' />
+
+////["words"] as string
+
+verify.codeFix({
+    description: "Add 'unknown' conversion for non-overlapping types",
+    newFileContent: `["words"] as unknown as string`
+});

tests/cases/fourslash/codeFixAddConvertToUnknownForNonOverlappingTypes4.ts

@@ -0,0 +1,8 @@
+/// <reference path='fourslash.ts' />
+
+////"words" as object
+
+verify.codeFix({
+    description: "Add 'unknown' conversion for non-overlapping types",
+    newFileContent: `"words" as unknown as object`
+});

tests/cases/fourslash/codeFixAddConvertToUnknownForNonOverlappingTypes5.ts

@@ -0,0 +1,8 @@
+/// <reference path='fourslash.ts' />
+
+////<string>0
+
+verify.codeFix({
+    description: "Add 'unknown' conversion for non-overlapping types",
+    newFileContent: `<string><unknown>0`
+});

tests/cases/fourslash/codeFixAddConvertToUnknownForNonOverlappingTypes6.ts

@@ -0,0 +1,8 @@
+/// <reference path='fourslash.ts' />
+
+////<string>0 * (4 + 3) / 100
+
+verify.codeFix({
+    description: "Add 'unknown' conversion for non-overlapping types",
+    newFileContent: `<string><unknown>0 * (4 + 3) / 100`
+});

tests/cases/fourslash/codeFixAddConvertToUnknownForNonOverlappingTypes7.ts

@@ -0,0 +1,8 @@
+/// <reference path='fourslash.ts' />
+
+////<string>["words"]
+
+verify.codeFix({
+    description: "Add 'unknown' conversion for non-overlapping types",
+    newFileContent: `<string><unknown>["words"]`
+});

tests/cases/fourslash/codeFixAddConvertToUnknownForNonOverlappingTypes8.ts

@@ -0,0 +1,8 @@
+/// <reference path='fourslash.ts' />
+
+////<object>"words"
+
+verify.codeFix({
+    description: "Add 'unknown' conversion for non-overlapping types",
+    newFileContent: `<object><unknown>"words"`
+});

tests/cases/fourslash/codeFixAddConvertToUnknownForNonOverlappingTypes_all.ts

@@ -0,0 +1,18 @@
+/// <reference path='fourslash.ts' />
+
+////const s1 = 1 as string;
+////const o1 = s + " word" as object;
+////
+////const s2 = <string>2;
+////const o2 = <object>s2;
+
+verify.codeFixAll({
+    fixId: "addConvertToUnknownForNonOverlappingTypes",
+    fixAllDescription: "Add 'unknown' to all conversions of non-overlapping types",
+    newFileContent:
+`const s1 = 1 as unknown as string;
+const o1 = s + " word" as unknown as object;
+
+const s2 = <string><unknown>2;
+const o2 = <object><unknown>s2;`
+});