Properly remove ! from definite assignment assertions

src/parser/plugins/types.ts

@@ -1,6 +1,6 @@
-import {eat, lookaheadType, match} from "../tokenizer/index";
+import {eatTypeToken, lookaheadType, match} from "../tokenizer/index";
 import {TokenType as tt} from "../tokenizer/types";
-import {isFlowEnabled, isTypeScriptEnabled, state} from "../traverser/base";
+import {isFlowEnabled, isTypeScriptEnabled} from "../traverser/base";
 import {baseParseConditional} from "../traverser/expression";
 import {flowParseTypeAnnotation} from "./flow";
 import {tsParseTypeAnnotation} from "./typescript";
@@ -26,9 +26,7 @@ export function typedParseConditional(noIn: boolean): void {
 // Note: These "type casts" are *not* valid TS expressions.
 // But we parse them here and change them when completing the arrow function.
 export function typedParseParenItem(): void {
-  if (eat(tt.question)) {
-    state.tokens[state.tokens.length - 1].isType = true;
-  }
+  eatTypeToken(tt.question);
   if (match(tt.colon)) {
     if (isTypeScriptEnabled) {
       tsParseTypeAnnotation();

src/parser/tokenizer/index.ts

@@ -189,6 +189,13 @@ export function eat(type: TokenType): boolean {
   }
 }
 
+export function eatTypeToken(tokenType: TokenType): void {
+  const oldIsType = state.isType;
+  state.isType = true;
+  eat(tokenType);
+  state.isType = oldIsType;
+}
+
 export function match(type: TokenType): boolean {
   return state.type === type;
 }

src/parser/traverser/statement.ts

@@ -36,6 +36,7 @@ import {
 } from "../plugins/typescript";
 import {
   eat,
+  eatTypeToken,
   IdentifierRole,
   lookaheadType,
   lookaheadTypeAndKeyword,
@@ -819,7 +820,7 @@ export function parsePostMemberNameModifiers(): void {
 
 export function parseClassProperty(): void {
   if (isTypeScriptEnabled) {
-    eat(tt.bang);
+    eatTypeToken(tt.bang);
     tsTryParseTypeAnnotation();
   } else if (isFlowEnabled) {
     if (match(tt.colon)) {

test/typescript-test.ts

@@ -1074,6 +1074,22 @@ describe("typescript transform", () => {
     );
   });
 
+  it("handles definite assignment assertions in classes with disableESTransforms", () => {
+    assertTypeScriptResult(
+      `
+      class A {
+        foo!: number;
+      }
+    `,
+      `"use strict";
+      class A {
+        foo;
+      }
+    `,
+      {disableESTransforms: true},
+    );
+  });
+
   it("handles definite assignment assertions on variables", () => {
     assertTypeScriptResult(
       `
@@ -1089,6 +1105,37 @@ describe("typescript transform", () => {
     );
   });
 
+  it("handles definite assignment assertions on private fields in classes", () => {
+    assertTypeScriptResult(
+      `
+      class A {
+        #a!: number;
+      }
+    `,
+      `"use strict";
+      class A {
+        #a;
+      }
+    `,
+    );
+  });
+
+  it("handles definite assignment assertions on private fields in classes with disableESTransforms", () => {
+    assertTypeScriptResult(
+      `
+      class A {
+        #a!: number;
+      }
+    `,
+      `"use strict";
+      class A {
+        #a;
+      }
+    `,
+      {disableESTransforms: true},
+    );
+  });
+
   it("handles mapped type modifiers", () => {
     assertTypeScriptResult(
       `