feat(parser): report error for missing initializer in using decl (#19824)

crates/oxc_parser/src/js/declaration.rs

@@ -161,6 +161,8 @@ impl<'a, C: Config> ParserImpl<'a, C> {
             } else if decl.kind == VariableDeclarationKind::Const {
                 // It is a Syntax Error if Initializer is not present and IsConstantDeclaration of the LexicalDeclaration containing this LexicalBinding is true.
                 self.error(diagnostics::missing_initializer_in_const(decl.id.span()));
+            } else if decl.kind.is_using() {
+                self.error(diagnostics::using_declarations_must_be_initialized(decl.id.span()));
             }
         }
     }
@@ -186,8 +188,12 @@ impl<'a, C: Config> ParserImpl<'a, C> {
         // BindingList[?In, ?Yield, ?Await, ~Pattern]
         let mut declarations = self.ast.vec();
         loop {
-            let declaration =
-                self.parse_variable_declarator(VariableDeclarationParent::Statement, kind);
+            let decl_parent = if matches!(statement_ctx, StatementContext::For) {
+                VariableDeclarationParent::For
+            } else {
+                VariableDeclarationParent::Statement
+            };
+            let declaration = self.parse_variable_declarator(decl_parent, kind);
 
             if !matches!(declaration.id, BindingPattern::BindingIdentifier(_)) {
                 self.error(diagnostics::invalid_identifier_in_using_declaration(
@@ -195,13 +201,6 @@ impl<'a, C: Config> ParserImpl<'a, C> {
                 ));
             }
 
-            // Excluding `for` loops, an initializer is required in a UsingDeclaration.
-            if declaration.init.is_none() && !matches!(statement_ctx, StatementContext::For) {
-                self.error(diagnostics::using_declarations_must_be_initialized(
-                    declaration.id.span(),
-                ));
-            }
-
             declarations.push(declaration);
             if !self.eat(Kind::Comma) {
                 break;

tasks/coverage/snapshots/parser_babel.snap

@@ -3,9 +3,7 @@ commit: 308c8d85
 parser_babel Summary:
 AST Parsed     : 2227/2227 (100.00%)
 Positive Passed: 2214/2227 (99.42%)
-Negative Passed: 1675/1692 (99.00%)
-Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/es2026/explicit-resource-management/invalid-for-using-of-no-initializer/input.js
-
+Negative Passed: 1676/1692 (99.05%)
 Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/cast/unparenthesized-assert-and-assign/input.ts
 
 Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/cast/unparenthesized-type-assertion-and-assign/input.ts
@@ -8949,6 +8947,13 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ·               ──
    ╰────
 
+  × Using declarations must have an initializer.
+   ╭─[babel/packages/babel-parser/test/fixtures/es2026/explicit-resource-management/invalid-for-using-of-no-initializer/input.js:1:12]
+ 1 │ for (using of;of.isValid;);
+   ·            ──
+   ╰────
+  help: Add an initializer (e.g. ` = undefined`) here
+
   × Lexical declaration cannot appear in a single-statement context
    ╭─[babel/packages/babel-parser/test/fixtures/es2026/explicit-resource-management/invalid-in-single-statement-context/input.js:2:13]
  1 │ {
@@ -13175,15 +13180,6 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: Try inserting a semicolon here
 
-  × Using declarations must have an initializer.
-   ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-await-using/input.ts:2:15]
- 1 │ declare namespace invalid_namespace_var {
- 2 │   await using A;
-   ·               ─
- 3 │   await using A1 = 0;
-   ╰────
-  help: Add an initializer (e.g. ` = undefined`) here
-
   × TS(1039): Initializers are not allowed in ambient contexts.
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-await-using/input.ts:3:20]
  2 │   await using A;
@@ -13200,33 +13196,6 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
  5 │   await using B, C;
    ╰────
 
-  × Using declarations must have an initializer.
-   ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-await-using/input.ts:5:15]
- 4 │   await using A2: number = 0;
- 5 │   await using B, C;
-   ·               ─
- 6 │ }
-   ╰────
-  help: Add an initializer (e.g. ` = undefined`) here
-
-  × Using declarations must have an initializer.
-   ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-await-using/input.ts:5:18]
- 4 │   await using A2: number = 0;
- 5 │   await using B, C;
-   ·                  ─
- 6 │ }
-   ╰────
-  help: Add an initializer (e.g. ` = undefined`) here
-
-  × Using declarations must have an initializer.
-   ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-using/input.ts:2:9]
- 1 │ declare namespace invalid_namespace_var {
- 2 │   using A;
-   ·         ─
- 3 │   using A1 = 0;
-   ╰────
-  help: Add an initializer (e.g. ` = undefined`) here
-
   × TS(1039): Initializers are not allowed in ambient contexts.
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-using/input.ts:3:14]
  2 │   using A;
@@ -13243,24 +13212,6 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
  5 │   using B, C;
    ╰────
 
-  × Using declarations must have an initializer.
-   ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-using/input.ts:5:9]
- 4 │   using A2: number = 0;
- 5 │   using B, C;
-   ·         ─
- 6 │ }
-   ╰────
-  help: Add an initializer (e.g. ` = undefined`) here
-
-  × Using declarations must have an initializer.
-   ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-using/input.ts:5:12]
- 4 │   using A2: number = 0;
- 5 │   using B, C;
-   ·            ─
- 6 │ }
-   ╰────
-  help: Add an initializer (e.g. ` = undefined`) here
-
   × TS(1039): Initializers are not allowed in ambient contexts.
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-var/input.ts:2:11]
  1 │ declare namespace invalid_namespace_var {

tasks/coverage/snapshots/parser_typescript.snap

@@ -3,7 +3,7 @@ commit: 34725489
 parser_typescript Summary:
 AST Parsed     : 9831/9834 (99.97%)
 Positive Passed: 9820/9834 (99.86%)
-Negative Passed: 1528/2578 (59.27%)
+Negative Passed: 1527/2578 (59.23%)
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/FunctionDeclaration3.ts
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/FunctionDeclaration4.ts
@@ -1954,9 +1954,11 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/scanner/e
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.14.ts
 
+Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.16.ts
+
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarationsInForOf.4.ts
 
-Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/usingDeclarationsInForOf.4.ts
+Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/usingDeclarations.16.ts
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/statements/for-inStatements/for-inStatementsArrayErrors.ts
 
@@ -25842,42 +25844,6 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/parser/ecmasc
    ╰────
   help: Wrap this code in a block or use a module
 
-  × Using declarations must have an initializer.
-   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.16.ts:2:17]
- 1 │ declare namespace N {
- 2 │     await using x: { [Symbol.asyncDispose](): Promise<void> };
-   ·                 ─
- 3 │     await using y: null;
-   ╰────
-  help: Add an initializer (e.g. ` = undefined`) here
-
-  × Using declarations must have an initializer.
-   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.16.ts:3:17]
- 2 │     await using x: { [Symbol.asyncDispose](): Promise<void> };
- 3 │     await using y: null;
-   ·                 ─
- 4 │ }
-   ╰────
-  help: Add an initializer (e.g. ` = undefined`) here
-
-  × Using declarations must have an initializer.
-   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.16.ts:6:17]
- 5 │ declare module 'M' {
- 6 │     await using x: { [Symbol.asyncDispose](): Promise<void> };
-   ·                 ─
- 7 │     await using y: null;
-   ╰────
-  help: Add an initializer (e.g. ` = undefined`) here
-
-  × Using declarations must have an initializer.
-   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.16.ts:7:17]
- 6 │     await using x: { [Symbol.asyncDispose](): Promise<void> };
- 7 │     await using y: null;
-   ·                 ─
- 8 │ }
-   ╰────
-  help: Add an initializer (e.g. ` = undefined`) here
-
   × Using declaration cannot appear in the bare case statement.
    ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.17.ts:3:9]
  2 │     case 0:
@@ -25993,15 +25959,6 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/parser/ecmasc
    ╰────
   help: Did you mean to use a for...of statement?
 
-  × Missing initializer in destructuring declaration
-   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarationsInForOf.3.ts:2:22]
- 1 │ async function main() {
- 2 │     for (await using {} of []) {
-   ·                      ──
- 3 │     }
-   ╰────
-  help: Add an initializer (e.g. ` = undefined`) here
-
   × Using declarations may not have binding patterns.
    ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarationsInForOf.3.ts:2:22]
  1 │ async function main() {
@@ -26043,42 +26000,6 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/parser/ecmasc
    ╰────
   help: Remove the `export` here and add `export { x }` as a separate statement to export the declaration
 
-  × Using declarations must have an initializer.
-   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/usingDeclarations.16.ts:2:11]
- 1 │ declare namespace N {
- 2 │     using x: { [Symbol.dispose](): void };
-   ·           ─
- 3 │     using y: null;
-   ╰────
-  help: Add an initializer (e.g. ` = undefined`) here
-
-  × Using declarations must have an initializer.
-   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/usingDeclarations.16.ts:3:11]
- 2 │     using x: { [Symbol.dispose](): void };
- 3 │     using y: null;
-   ·           ─
- 4 │ }
-   ╰────
-  help: Add an initializer (e.g. ` = undefined`) here
-
-  × Using declarations must have an initializer.
-   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/usingDeclarations.16.ts:6:11]
- 5 │ declare module 'M' {
- 6 │     using x: { [Symbol.dispose](): void };
-   ·           ─
- 7 │     using y: null;
-   ╰────
-  help: Add an initializer (e.g. ` = undefined`) here
-
-  × Using declarations must have an initializer.
-   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/usingDeclarations.16.ts:7:11]
- 6 │     using x: { [Symbol.dispose](): void };
- 7 │     using y: null;
-   ·           ─
- 8 │ }
-   ╰────
-  help: Add an initializer (e.g. ` = undefined`) here
-
   × Using declaration cannot appear in the bare case statement.
    ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/usingDeclarations.17.ts:3:9]
  2 │     case 0:
@@ -26180,6 +26101,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/parser/ecmasc
  2 │ }
    ╰────
 
+  × Using declarations must have an initializer.
+   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/usingDeclarationsInForOf.4.ts:3:12]
+ 2 │ for (using of: null = null;;) break;
+ 3 │ for (using of;;) break;
+   ·            ──
+   ╰────
+  help: Add an initializer (e.g. ` = undefined`) here
+
   × Illegal break statement
    ╭─[typescript/tests/cases/conformance/statements/breakStatements/invalidDoWhileBreakStatements.ts:4:1]
  3 │ // naked break not allowed