fix(parser): reject invalid modifiers on import aliases (#26622)

Oxc currently accepts and discards invalid modifiers on TypeScript import aliases. Validate them before constructing the declaration: `declare import X = A.B;` now reports TS1079, and `abstract import X = A.B;` reports TS1242.

Adds regression coverage for modifier combinations and exported, ambient, external, and type-only aliases. Valid aliases retain their existing behavior.

crates/oxc_parser/src/diagnostics.rs

@@ -889,6 +889,11 @@ parser_diagnostics! {
         OxcDiagnostic::error("import() requires a specifier.").with_label(span)
     };
 
+    declare_modifier_on_import(span: Span) => {
+        ts_error("1079", "A 'declare' modifier cannot be used with an import declaration.")
+            .with_label(span)
+    };
+
     modifier_cannot_be_used_here(modifier: Modifier, allowed: Option<ModifierKinds>) => {
         OxcDiagnostic::error(format!("'{}' modifier cannot be used here.", modifier.kind))
             .with_label(modifier.span())

crates/oxc_parser/src/ts/statement.rs

@@ -689,6 +689,20 @@ impl<'a, C: Config> ParserImpl<'a, C> {
                 Declaration::ClassDeclaration(decl)
             }
             Kind::Import => {
+                self.verify_modifiers(
+                    modifiers,
+                    ModifierKinds::new([ModifierKind::Export]),
+                    true,
+                    |modifier, allowed| match modifier.kind {
+                        ModifierKind::Declare => {
+                            diagnostics::declare_modifier_on_import(modifier.span())
+                        }
+                        ModifierKind::Abstract => {
+                            diagnostics::illegal_abstract_modifier(modifier.span())
+                        }
+                        _ => diagnostics::modifier_cannot_be_used_here(modifier, allowed),
+                    },
+                );
                 self.bump_any();
                 let token = self.cur_token();
                 let mut import_kind = ImportOrExportKind::Value;

tasks/coverage/misc/fail/import-equals-modifier-abstract-type-require.ts

@@ -0,0 +1,2 @@
+namespace A { export class B {} }
+abstract import type X = require("external");

tasks/coverage/misc/fail/import-equals-modifier-abstract.ts

@@ -0,0 +1,2 @@
+namespace A { export class B {} }
+abstract import X = A.B;

tasks/coverage/misc/fail/import-equals-modifier-declare-abstract.ts

@@ -0,0 +1,2 @@
+namespace A { export class B {} }
+declare abstract import X = A.B;

tasks/coverage/misc/fail/import-equals-modifier-declare-require.ts

@@ -0,0 +1,2 @@
+namespace A { export class B {} }
+declare import X = require("external");

tasks/coverage/misc/fail/import-equals-modifier-export-abstract.ts

@@ -0,0 +1,2 @@
+namespace A { export class B {} }
+export abstract import X = A.B;

tasks/coverage/misc/fail/import-equals-modifier-export-declare-type-require.ts

@@ -0,0 +1,2 @@
+namespace A { export class B {} }
+export declare import type X = require("external");

tasks/coverage/misc/fail/import-equals-modifier-export-declare.ts

@@ -0,0 +1,2 @@
+namespace A { export class B {} }
+export declare import X = A.B;

tasks/coverage/misc/pass/import-equals-modifiers.ts

@@ -0,0 +1,10 @@
+namespace A { export class B {} }
+import Local = A.B;
+export import Exported = A.B;
+import External = require("external");
+export import ExportedExternal = require("external");
+export import type ExportedType = require("external");
+declare namespace Ambient {
+    import Local = A.B;
+    export import Exported = A.B;
+}

tasks/coverage/snapshots/codegen_misc.snap

@@ -1,3 +1,3 @@
 codegen_misc Summary:
-AST Parsed     : 110/110 (100.00%)
-Positive Passed: 110/110 (100.00%)
+AST Parsed     : 111/111 (100.00%)
+Positive Passed: 111/111 (100.00%)

tasks/coverage/snapshots/formatter_misc.snap

@@ -1,3 +1,3 @@
 formatter_misc Summary:
-AST Parsed     : 110/110 (100.00%)
-Positive Passed: 110/110 (100.00%)
+AST Parsed     : 111/111 (100.00%)
+Positive Passed: 111/111 (100.00%)

tasks/coverage/snapshots/lexer_misc.snap

@@ -1,3 +1,3 @@
 lexer_misc Summary:
-AST Parsed     : 337/337 (100.00%)
-Positive Passed: 337/337 (100.00%)
+AST Parsed     : 345/345 (100.00%)
+Positive Passed: 345/345 (100.00%)

tasks/coverage/snapshots/parser_misc.snap

@@ -1,7 +1,7 @@
 parser_misc Summary:
-AST Parsed     : 110/110 (100.00%)
-Positive Passed: 110/110 (100.00%)
-Negative Passed: 227/227 (100.00%)
+AST Parsed     : 111/111 (100.00%)
+Positive Passed: 111/111 (100.00%)
+Negative Passed: 234/234 (100.00%)
 
   × TS(1275): 'accessor' modifier can only appear on a property declaration.
    ╭─[misc/fail/accessor-modifier-abstract-method.ts:1:29]
@@ -936,6 +936,62 @@ Negative Passed: 227/227 (100.00%)
    ·                  ╰── `from` expected
    ╰────
 
+  × TS(1242): 'abstract' modifier can only appear on a class, method, or property declaration.
+   ╭─[misc/fail/import-equals-modifier-abstract-type-require.ts:2:1]
+ 1 │ namespace A { export class B {} }
+ 2 │ abstract import type X = require("external");
+   · ────────
+   ╰────
+
+  × TS(1242): 'abstract' modifier can only appear on a class, method, or property declaration.
+   ╭─[misc/fail/import-equals-modifier-abstract.ts:2:1]
+ 1 │ namespace A { export class B {} }
+ 2 │ abstract import X = A.B;
+   · ────────
+   ╰────
+
+  × TS(1079): A 'declare' modifier cannot be used with an import declaration.
+   ╭─[misc/fail/import-equals-modifier-declare-abstract.ts:2:1]
+ 1 │ namespace A { export class B {} }
+ 2 │ declare abstract import X = A.B;
+   · ───────
+   ╰────
+
+  × TS(1242): 'abstract' modifier can only appear on a class, method, or property declaration.
+   ╭─[misc/fail/import-equals-modifier-declare-abstract.ts:2:9]
+ 1 │ namespace A { export class B {} }
+ 2 │ declare abstract import X = A.B;
+   ·         ────────
+   ╰────
+
+  × TS(1079): A 'declare' modifier cannot be used with an import declaration.
+   ╭─[misc/fail/import-equals-modifier-declare-require.ts:2:1]
+ 1 │ namespace A { export class B {} }
+ 2 │ declare import X = require("external");
+   · ───────
+   ╰────
+
+  × TS(1242): 'abstract' modifier can only appear on a class, method, or property declaration.
+   ╭─[misc/fail/import-equals-modifier-export-abstract.ts:2:8]
+ 1 │ namespace A { export class B {} }
+ 2 │ export abstract import X = A.B;
+   ·        ────────
+   ╰────
+
+  × TS(1079): A 'declare' modifier cannot be used with an import declaration.
+   ╭─[misc/fail/import-equals-modifier-export-declare-type-require.ts:2:8]
+ 1 │ namespace A { export class B {} }
+ 2 │ export declare import type X = require("external");
+   ·        ───────
+   ╰────
+
+  × TS(1079): A 'declare' modifier cannot be used with an import declaration.
+   ╭─[misc/fail/import-equals-modifier-export-declare.ts:2:8]
+ 1 │ namespace A { export class B {} }
+ 2 │ export declare import X = A.B;
+   ·        ───────
+   ╰────
+
   × Identifier expected. 'this' is a reserved word that cannot be used here.
    ╭─[misc/fail/import-equals-this.ts:2:12]
  1 │ // `this` is not valid in import equals declaration

tasks/coverage/snapshots/parser_typescript.snap

@@ -3,7 +3,7 @@ commit: b465fdbf
 parser_typescript Summary:
 AST Parsed     : 9783/9783 (100.00%)
 Positive Passed: 9783/9783 (100.00%)
-Negative Passed: 1649/2636 (62.56%)
+Negative Passed: 1651/2636 (62.63%)
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/FunctionDeclaration3.ts
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/FunctionDeclaration4.ts
@@ -202,8 +202,6 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/declarationE
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/declarationEmitUsingTypeAlias1.ts
 
-Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/declareModifierOnImport1.ts
-
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/decoratorsOnComputedProperties.ts
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/defaultArgsInOverloads.ts
@@ -450,8 +448,6 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/importAndVar
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/importAssertionsDeprecated.ts
 
-Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/importDeclWithClassModifiers.ts
-
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/importTypeAssertionDeprecation.ts
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/importWithTrailingSlash.ts
@@ -5863,6 +5859,12 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/wit
    ╰────
   help: Remove the duplicate modifier.
 
+  × TS(1079): A 'declare' modifier cannot be used with an import declaration.
+   ╭─[typescript/tests/cases/compiler/declareModifierOnImport1.ts:1:1]
+ 1 │ declare import a = b;
+   · ───────
+   ╰────
+
   × Expected `,` or `)` but found `:`
    ╭─[typescript/tests/cases/compiler/decoratorInJsFile.ts:3:10]
  2 │ class SomeClass {
@@ -7774,6 +7776,33 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/wit
    ╰────
   help: Wrap this with quotes
 
+  × 'public' modifier cannot be used here.
+   ╭─[typescript/tests/cases/compiler/importDeclWithClassModifiers.ts:5:8]
+ 4 │ }
+ 5 │ export public import a = x.c;
+   ·        ──────
+ 6 │ export private import b = x.c;
+   ╰────
+  help: Only 'export' modifier is allowed here.
+
+  × 'private' modifier cannot be used here.
+   ╭─[typescript/tests/cases/compiler/importDeclWithClassModifiers.ts:6:8]
+ 5 │ export public import a = x.c;
+ 6 │ export private import b = x.c;
+   ·        ───────
+ 7 │ export static import c = x.c;
+   ╰────
+  help: Only 'export' modifier is allowed here.
+
+  × 'static' modifier cannot be used here.
+   ╭─[typescript/tests/cases/compiler/importDeclWithClassModifiers.ts:7:8]
+ 6 │ export private import b = x.c;
+ 7 │ export static import c = x.c;
+   ·        ──────
+ 8 │ var b: a;
+   ╰────
+  help: Only 'export' modifier is allowed here.
+
   × TS(1029): 'export' modifier must precede 'declare' modifier.
    ╭─[typescript/tests/cases/compiler/importDeclWithDeclareModifier.ts:5:9]
  4 │ }
@@ -7782,6 +7811,14 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/wit
  6 │ var b: a;
    ╰────
 
+  × TS(1079): A 'declare' modifier cannot be used with an import declaration.
+   ╭─[typescript/tests/cases/compiler/importDeclWithDeclareModifier.ts:5:1]
+ 4 │ }
+ 5 │ declare export import a = x.c;
+   · ───────
+ 6 │ var b: a;
+   ╰────
+
   × TS(1029): 'export' modifier must precede 'declare' modifier.
    ╭─[typescript/tests/cases/compiler/importDeclWithDeclareModifierInAmbientContext.ts:6:13]
  5 │     }
@@ -7793,6 +7830,14 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/wit
   × TS(1038): A 'declare' modifier cannot be used in an already ambient context.
    ╭─[typescript/tests/cases/compiler/importDeclWithDeclareModifierInAmbientContext.ts:6:5]
  5 │     }
+ 6 │     declare export import a = x.c;
+   ·     ───────
+ 7 │     var b: a;
+   ╰────
+
+  × TS(1079): A 'declare' modifier cannot be used with an import declaration.
+   ╭─[typescript/tests/cases/compiler/importDeclWithDeclareModifierInAmbientContext.ts:6:5]
+ 5 │     }
  6 │     declare export import a = x.c;
    ·     ───────
  7 │     var b: a;
@@ -17752,6 +17797,15 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/wit
     ╰────
   help: Allowed modifiers are: declare, async
 
+  × 'accessor' modifier cannot be used here.
+    ╭─[typescript/tests/cases/conformance/classes/propertyMemberDeclarations/autoAccessorDisallowedModifiers.ts:34:1]
+ 33 │ accessor function F1() {}
+ 34 │ accessor import "x";
+    · ────────
+ 35 │ accessor import {} from "x";
+    ╰────
+  help: Only 'export' modifier is allowed here.
+
   × Unexpected token
     ╭─[typescript/tests/cases/conformance/classes/propertyMemberDeclarations/autoAccessorDisallowedModifiers.ts:34:17]
  33 │ accessor function F1() {}

tasks/coverage/snapshots/semantic_misc.snap

@@ -1,11 +1,19 @@
 semantic_misc Summary:
-AST Parsed     : 110/110 (100.00%)
-Positive Passed: 105/110 (95.45%)
+AST Parsed     : 111/111 (100.00%)
+Positive Passed: 105/111 (94.59%)
 semantic Error: tasks/coverage/misc/pass/declare-let-private.ts
 Bindings mismatch:
 after transform: ScopeId(0): ["private"]
 rebuilt        : ScopeId(0): []
 
+semantic Error: tasks/coverage/misc/pass/import-equals-modifiers.ts
+Bindings mismatch:
+after transform: ScopeId(0): ["A", "Ambient", "Exported", "ExportedExternal", "ExportedType"]
+rebuilt        : ScopeId(0): ["A", "Exported", "ExportedExternal"]
+Symbol reference IDs mismatch for "A":
+after transform: SymbolId(0): [ReferenceId(1), ReferenceId(2), ReferenceId(3), ReferenceId(6), ReferenceId(7)]
+rebuilt        : SymbolId(0): [ReferenceId(2), ReferenceId(3), ReferenceId(4)]
+
 semantic Error: tasks/coverage/misc/pass/oxc-11593.ts
 Scope parent mismatch:
 after transform: ScopeId(2): Some(ScopeId(1))

tasks/coverage/snapshots/transformer_misc.snap

@@ -1,3 +1,3 @@
 transformer_misc Summary:
-AST Parsed     : 110/110 (100.00%)
-Positive Passed: 110/110 (100.00%)
+AST Parsed     : 111/111 (100.00%)
+Positive Passed: 111/111 (100.00%)