feat(parser): missing initializer in destructuring declaration inside for loop head (#8222)

closes #8220

crates/oxc_parser/src/js/declaration.rs

@@ -3,7 +3,7 @@ use oxc_ast::{ast::*, NONE};
 use oxc_diagnostics::Result;
 use oxc_span::{GetSpan, Span};
 
-use super::{VariableDeclarationContext, VariableDeclarationParent};
+use super::VariableDeclarationParent;
 use crate::{
     diagnostics,
     lexer::Kind,
@@ -45,7 +45,7 @@ impl<'a> ParserImpl<'a> {
     pub(crate) fn parse_variable_declaration(
         &mut self,
         start_span: Span,
-        decl_ctx: VariableDeclarationContext,
+        decl_parent: VariableDeclarationParent,
         modifiers: &Modifiers<'a>,
     ) -> Result<Box<'a, VariableDeclaration<'a>>> {
         let kind = match self.cur_kind() {
@@ -58,17 +58,14 @@ impl<'a> ParserImpl<'a> {
 
         let mut declarations = self.ast.vec();
         loop {
-            let declaration = self.parse_variable_declarator(decl_ctx, kind)?;
+            let declaration = self.parse_variable_declarator(decl_parent, kind)?;
             declarations.push(declaration);
             if !self.eat(Kind::Comma) {
                 break;
             }
         }
 
-        if matches!(
-            decl_ctx.parent,
-            VariableDeclarationParent::Statement | VariableDeclarationParent::Clause
-        ) {
+        if matches!(decl_parent, VariableDeclarationParent::Statement) {
             self.asi()?;
         }
 
@@ -88,7 +85,7 @@ impl<'a> ParserImpl<'a> {
 
     fn parse_variable_declarator(
         &mut self,
-        decl_ctx: VariableDeclarationContext,
+        decl_parent: VariableDeclarationParent,
         kind: VariableDeclarationKind,
     ) -> Result<VariableDeclarator<'a>> {
         let span = self.start_span();
@@ -115,27 +112,24 @@ impl<'a> ParserImpl<'a> {
         } else {
             (self.ast.binding_pattern(binding_kind, NONE, false), false)
         };
-
         let init =
             self.eat(Kind::Eq).then(|| self.parse_assignment_expression_or_higher()).transpose()?;
+        let decl = self.ast.variable_declarator(self.end_span(span), kind, id, init, definite);
+        if decl_parent == VariableDeclarationParent::Statement {
+            self.check_missing_initializer(&decl);
+        }
+        Ok(decl)
+    }
 
-        if init.is_none()
-            && !self.ctx.has_ambient()
-            && decl_ctx.parent == VariableDeclarationParent::Statement
-        {
-            // LexicalBinding[In, Yield, Await] :
-            //   BindingIdentifier[?Yield, ?Await] Initializer[?In, ?Yield, ?Await] opt
-            //   BindingPattern[?Yield, ?Await] Initializer[?In, ?Yield, ?Await]
-            // the grammar forbids `let []`, `let {}`
-            if !matches!(id.kind, BindingPatternKind::BindingIdentifier(_)) {
-                self.error(diagnostics::invalid_destrucuring_declaration(id.span()));
-            } else if kind == VariableDeclarationKind::Const {
+    pub(crate) fn check_missing_initializer(&mut self, decl: &VariableDeclarator<'a>) {
+        if decl.init.is_none() && !self.ctx.has_ambient() {
+            if !matches!(decl.id.kind, BindingPatternKind::BindingIdentifier(_)) {
+                self.error(diagnostics::invalid_destrucuring_declaration(decl.id.span()));
+            } 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::missinginitializer_in_const(id.span()));
+                self.error(diagnostics::missinginitializer_in_const(decl.id.span()));
             }
         }
-
-        Ok(self.ast.variable_declarator(self.end_span(span), kind, id, init, definite))
     }
 
     /// Section 14.3.1 Let, Const, and Using Declarations
@@ -168,7 +162,7 @@ impl<'a> ParserImpl<'a> {
         let mut declarations: oxc_allocator::Vec<'_, VariableDeclarator<'_>> = self.ast.vec();
         loop {
             let declaration = self.parse_variable_declarator(
-                VariableDeclarationContext::new(VariableDeclarationParent::Statement),
+                VariableDeclarationParent::Statement,
                 VariableDeclarationKind::Var,
             )?;
 

crates/oxc_parser/src/js/mod.rs

@@ -34,16 +34,4 @@ pub enum FunctionKind {
 pub enum VariableDeclarationParent {
     For,
     Statement,
-    Clause,
-}
-
-#[derive(Debug, Clone, Copy, Eq, PartialEq)]
-pub struct VariableDeclarationContext {
-    pub parent: VariableDeclarationParent,
-}
-
-impl VariableDeclarationContext {
-    pub(crate) fn new(parent: VariableDeclarationParent) -> Self {
-        Self { parent }
-    }
 }

crates/oxc_parser/src/js/module.rs

@@ -354,13 +354,15 @@ impl<'a> ParserImpl<'a> {
         // For tc39/proposal-decorators
         // For more information, please refer to <https://babeljs.io/docs/babel-plugin-proposal-decorators#decoratorsbeforeexport>
         self.eat_decorators()?;
+        let reserved_ctx = self.ctx;
         let modifiers =
             if self.is_ts { self.eat_modifiers_before_declaration()? } else { Modifiers::empty() };
+        self.ctx = self.ctx.union_ambient_if(modifiers.contains_declare());
 
         let declaration = self.parse_declaration(decl_span, &modifiers)?;
-        let span = self.end_span(span);
+        self.ctx = reserved_ctx;
         Ok(self.ast.alloc_export_named_declaration(
-            span,
+            self.end_span(span),
             Some(declaration),
             self.ast.vec(),
             None,

crates/oxc_parser/src/js/statement.rs

@@ -3,7 +3,7 @@ use oxc_ast::ast::*;
 use oxc_diagnostics::Result;
 use oxc_span::{Atom, GetSpan, Span};
 
-use super::{grammar::CoverGrammar, VariableDeclarationContext, VariableDeclarationParent};
+use super::{grammar::CoverGrammar, VariableDeclarationParent};
 use crate::{
     diagnostics, lexer::Kind, modifiers::Modifiers, Context, ParserImpl, StatementContext,
 };
@@ -174,7 +174,7 @@ impl<'a> ParserImpl<'a> {
         let start_span = self.start_span();
         let decl = self.parse_variable_declaration(
             start_span,
-            VariableDeclarationContext::new(VariableDeclarationParent::Statement),
+            VariableDeclarationParent::Statement,
             &Modifiers::empty(),
         )?;
 
@@ -309,7 +309,7 @@ impl<'a> ParserImpl<'a> {
     ) -> Result<Statement<'a>> {
         let start_span = self.start_span();
         let init_declaration = self.context(Context::empty(), Context::In, |p| {
-            let decl_ctx = VariableDeclarationContext::new(VariableDeclarationParent::For);
+            let decl_ctx = VariableDeclarationParent::For;
             p.parse_variable_declaration(start_span, decl_ctx, &Modifiers::empty())
         })?;
 
@@ -358,6 +358,11 @@ impl<'a> ParserImpl<'a> {
         r#await: bool,
     ) -> Result<Statement<'a>> {
         self.expect(Kind::Semicolon)?;
+        if let Some(ForStatementInit::VariableDeclaration(decl)) = &init {
+            for d in &decl.declarations {
+                self.check_missing_initializer(d);
+            }
+        }
         let test = if !self.at(Kind::Semicolon) && !self.at(Kind::RParen) {
             Some(self.context(Context::In, Context::empty(), ParserImpl::parse_expr)?)
         } else {

crates/oxc_parser/src/ts/statement.rs

@@ -5,7 +5,7 @@ use oxc_span::{GetSpan, Span};
 
 use crate::{
     diagnostics,
-    js::{FunctionKind, VariableDeclarationContext, VariableDeclarationParent},
+    js::{FunctionKind, VariableDeclarationParent},
     lexer::Kind,
     modifiers::{ModifierFlags, ModifierKind, Modifiers},
     ParserImpl,
@@ -379,7 +379,7 @@ impl<'a> ParserImpl<'a> {
             kind if kind.is_variable_declaration() => self
                 .parse_variable_declaration(
                     start_span,
-                    VariableDeclarationContext::new(VariableDeclarationParent::Clause),
+                    VariableDeclarationParent::Statement,
                     modifiers,
                 )
                 .map(Declaration::VariableDeclaration),

tasks/coverage/snapshots/parser_typescript.snap

@@ -3,7 +3,7 @@ commit: d85767ab
 parser_typescript Summary:
 AST Parsed     : 6494/6503 (99.86%)
 Positive Passed: 6483/6503 (99.69%)
-Negative Passed: 1275/5747 (22.19%)
+Negative Passed: 1277/5747 (22.22%)
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/ClassDeclaration24.ts
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/ExportAssignment7.ts
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/ExportAssignment8.ts
@@ -3182,7 +3182,6 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/externalM
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/externalModules/exportClassNameWithObjectSystem.ts
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/externalModules/exportClassNameWithObjectUMD.ts
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/externalModules/exportDefaultClassNameWithObject.ts
-Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/externalModules/exportNonInitializedVariablesInIfThenStatementNoCrash1.ts
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/externalModules/exportNonLocalDeclarations.ts
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/externalModules/importNonExternalModule.ts
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/externalModules/importTsBeforeDTs.ts
@@ -4080,7 +4079,6 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/statement
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/statements/for-ofStatements/ES5For-ofTypeCheck9.ts
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/statements/forStatements/forStatementsMultipleInvalidDecl.ts
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/statements/ifDoWhileStatements/ifDoWhileStatements.ts
-Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/statements/labeledStatements/labeledStatementExportDeclarationNoCrash1.ts
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/statements/returnStatements/invalidReturnStatements.ts
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/statements/switchStatements/switchStatements.ts
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/any/anyAsConstructor.ts
@@ -6772,6 +6770,21 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/salsa/private
  5 │ 
    ╰────
 
+  × Missing initializer in const declaration
+    ╭─[typescript/tests/cases/compiler/constDeclarations-errors.ts:12:11]
+ 11 │ // error, can not be unintalized
+ 12 │ for(const c9; c9 < 1;) { }
+    ·           ──
+ 13 │ 
+    ╰────
+
+  × Missing initializer in const declaration
+    ╭─[typescript/tests/cases/compiler/constDeclarations-errors.ts:15:20]
+ 14 │ // error, can not be unintalized
+ 15 │ for(const c10 = 0, c11; c10 < 1;) { }
+    ·                    ───
+    ╰────
+
   × Lexical declaration cannot appear in a single-statement context
    ╭─[typescript/tests/cases/compiler/constDeclarations-invalidContexts.ts:3:5]
  2 │ if (true) 
@@ -19457,6 +19470,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/salsa/private
  2 │ let;
    ╰────
 
+  × Missing initializer in const declaration
+   ╭─[typescript/tests/cases/conformance/externalModules/exportNonInitializedVariablesInIfThenStatementNoCrash1.ts:4:14]
+ 3 │ if (true)
+ 4 │ export const cssExports: CssExports;
+   ·              ──────────────────────
+ 5 │ export default cssExports;
+   ╰────
+
   × Unexpected token
    ╭─[typescript/tests/cases/conformance/externalModules/exportNonInitializedVariablesSystem.ts:1:4]
  1 │ var;
@@ -24001,6 +24022,21 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/salsa/private
  14 │           `height: var foo`,
     ╰────
 
+  × Missing initializer in const declaration
+   ╭─[typescript/tests/cases/conformance/statements/labeledStatements/labeledStatementExportDeclarationNoCrash1.ts:3:14]
+ 2 │ 
+ 3 │ export const box: string
+   ·              ───────────
+ 4 │ subTitle:
+   ╰────
+
+  × Missing initializer in const declaration
+   ╭─[typescript/tests/cases/conformance/statements/labeledStatements/labeledStatementExportDeclarationNoCrash1.ts:5:14]
+ 4 │ subTitle:
+ 5 │ export const title: string
+   ·              ─────────────
+   ╰────
+
   × Generators can only be declared at the top level or inside a block
    ╭─[typescript/tests/cases/conformance/statements/labeledStatements/labeledStatementWithLabel.ts:2:8]
  1 │ label: function fn() { }