feat(parser): parse const type parameter from TypeScript v5.0 (#416)

Author: Boshen

crates/oxc_ast/src/ast/ts.rs

@@ -418,6 +418,7 @@ pub struct TSTypeParameter<'a> {
     pub default: Option<TSType<'a>>,
     pub r#in: bool,
     pub out: bool,
+    pub r#const: bool,
 }
 
 #[derive(Debug, Hash)]

crates/oxc_ast/src/ast_builder.rs

@@ -1056,8 +1056,9 @@ impl<'a> AstBuilder<'a> {
         default: Option<TSType<'a>>,
         r#in: bool,
         out: bool,
+        r#const: bool,
     ) -> Box<'a, TSTypeParameter<'a>> {
-        self.alloc(TSTypeParameter { span, name, constraint, default, r#in, out })
+        self.alloc(TSTypeParameter { span, name, constraint, default, r#in, out, r#const })
     }
 
     pub fn ts_type_parameters(

crates/oxc_parser/src/js/function.rs

@@ -400,7 +400,14 @@ impl<'a> Parser<'a> {
                 _ => IsParenthesizedArrowFunction::False,
             },
             Kind::LAngle => {
-                if !self.nth_kind(offset + 1).is_identifier() {
+                let kind = self.nth_kind(offset + 1);
+
+                // `<const` for const type parameter from TypeScript 5.0
+                if kind == Kind::Const {
+                    return IsParenthesizedArrowFunction::Maybe;
+                }
+
+                if !kind.is_identifier() {
                     return IsParenthesizedArrowFunction::False;
                 }
 

crates/oxc_parser/src/ts/types.rs

@@ -152,28 +152,44 @@ impl<'a> Parser<'a> {
     pub(crate) fn parse_ts_type_parameter(&mut self) -> Result<Box<'a, TSTypeParameter<'a>>> {
         let span = self.start_span();
 
-        let r#in = if self.at(Kind::In) && self.peek_kind().is_identifier_name() {
-            self.bump_any();
-            true
-        } else {
-            false
-        };
-        let out = if self.at(Kind::Out) && self.peek_kind().is_identifier_name() {
-            self.bump_any();
-            true
-        } else {
-            false
-        };
+        let mut r#in = false;
+        let mut out = false;
+        let mut r#const = false;
 
-        if self.at(Kind::In) && self.peek_kind().is_identifier_name() {
-            // TODO error
+        match self.cur_kind() {
+            Kind::In if self.peek_kind().is_identifier_name() => {
+                self.bump_any();
+                r#in = true;
+                if self.at(Kind::Out) && self.peek_kind().is_identifier_name() {
+                    // `<in out T>`
+                    self.bump_any();
+                    out = true;
+                }
+            }
+            Kind::Out if self.peek_kind().is_identifier_name() => {
+                self.bump_any();
+                out = true;
+            }
+            Kind::Const if self.peek_kind().is_identifier_name() => {
+                self.bump_any();
+                r#const = true;
+            }
+            _ => {}
         }
 
         let name = self.parse_binding_identifier()?;
         let constraint = self.parse_ts_type_constraint()?;
         let default = self.parse_ts_default_type()?;
 
-        Ok(self.ast.ts_type_parameter(self.end_span(span), name, constraint, default, r#in, out))
+        Ok(self.ast.ts_type_parameter(
+            self.end_span(span),
+            name,
+            constraint,
+            default,
+            r#in,
+            out,
+            r#const,
+        ))
     }
 
     fn parse_ts_type_constraint(&mut self) -> Result<Option<TSType<'a>>> {
@@ -617,6 +633,7 @@ impl<'a> Parser<'a> {
             None,
             false,
             false,
+            false,
         );
 
         let name_type = if self.eat(Kind::As) { Some(self.parse_ts_type()?) } else { None };
@@ -813,6 +830,7 @@ impl<'a> Parser<'a> {
             None,
             false,
             false,
+            false,
         );
 
         Ok(self.ast.ts_infer_type(self.end_span(span), type_parameter))

tasks/coverage/babel

@@ -1,3 +1,3 @@
 formatter_test262 Summary:
-AST Parsed     : 44745/44745 (100.00%)
-Positive Passed: 44745/44745 (100.00%)
+AST Parsed     : 44738/44738 (100.00%)
+Positive Passed: 44738/44738 (100.00%)

tasks/coverage/formatter_test262.snap

@@ -1,3 +1,3 @@
 minifier_test262 Summary:
-AST Parsed     : 44745/44745 (100.00%)
-Positive Passed: 44745/44745 (100.00%)
+AST Parsed     : 44738/44738 (100.00%)
+Positive Passed: 44738/44738 (100.00%)

tasks/coverage/minifier_test262.snap

@@ -1,7 +1,7 @@
 parser_babel Summary:
 AST Parsed     : 2072/2078 (99.71%)
 Positive Passed: 2069/2078 (99.57%)
-Negative Passed: 1332/1507 (88.39%)
+Negative Passed: 1330/1507 (88.25%)
 Expect Syntax Error: "annex-b/disabled/1.1-html-comments-close/input.js"
 Expect Syntax Error: "annex-b/disabled/3.1-sloppy-labeled-functions-if-body/input.js"
 Expect Syntax Error: "annex-b/disabled/3.1-sloppy-labeled-functions-multiple-labels/input.js"
@@ -161,6 +161,8 @@ Expect Syntax Error: "typescript/type-arguments/empty-type-ref/input.ts"
 Expect Syntax Error: "typescript/type-arguments/instantiation-expression-property-access/input.ts"
 Expect Syntax Error: "typescript/type-only-import-export-specifiers/export-invalid-type-in-type/input.ts"
 Expect Syntax Error: "typescript/type-only-import-export-specifiers/import-invalid-type-in-type/input.ts"
+Expect Syntax Error: "typescript/types/const-type-parameters-invalid-babel-7/input.ts"
+Expect Syntax Error: "typescript/types/const-type-parameters-invalid/input.ts"
 Expect Syntax Error: "typescript/types/import-type-declaration-error/input.ts"
 Expect Syntax Error: "typescript/types/import-type-dynamic-errors/input.ts"
 Expect Syntax Error: "typescript/types/intrinsic-keyword-error/input.ts"
@@ -250,19 +252,21 @@ Expect to Parse: "typescript/regression/nested-extends-in-arrow-type-param/input
 
 Expect to Parse: "typescript/types/const-type-parameters-babel-7/input.ts"
   × Unexpected token
-   ╭─[typescript/types/const-type-parameters-babel-7/input.ts:1:1]
- 1 │ function a<const T>() {}
-   ·            ─────
- 2 │ function b<const T extends U>() {}
-   ╰────
+    ╭─[typescript/types/const-type-parameters-babel-7/input.ts:13:1]
+ 13 │ class C<T, const U> {}
+ 14 │ class D<in const T> {}
+    ·            ─────
+ 15 │ class E<const in T> {}
+    ╰────
 
 Expect to Parse: "typescript/types/const-type-parameters/input.ts"
   × Unexpected token
-   ╭─[typescript/types/const-type-parameters/input.ts:1:1]
- 1 │ function a<const T>() {}
-   ·            ─────
- 2 │ function b<const T extends U>() {}
-   ╰────
+    ╭─[typescript/types/const-type-parameters/input.ts:13:1]
+ 13 │ class C<T, const U> {}
+ 14 │ class D<in const T> {}
+    ·            ─────
+ 15 │ class E<const in T> {}
+    ╰────
 
   × Identifier `f` has already been declared
    ╭─[annex-b/disabled/3.4-var-redeclaration-catch-binding/input.js:1:1]
@@ -10123,18 +10127,6 @@ Expect to Parse: "typescript/types/const-type-parameters/input.ts"
  1 │ type F = ({
    ╰────
 
-  × Unexpected token
-   ╭─[typescript/types/const-type-parameters-invalid-babel-7/input.ts:1:1]
- 1 │ type T<const U> = {};
-   ·        ─────
-   ╰────
-
-  × Unexpected token
-   ╭─[typescript/types/const-type-parameters-invalid/input.ts:1:1]
- 1 │ type T<const U> = {};
-   ·        ─────
-   ╰────
-
   × Keywords cannot contain escape characters
    ╭─[typescript/types/import-type-escaped-error/input.ts:1:1]
  1 │ import typ\u{65} typescript from "typescript";

tasks/coverage/parser_babel.snap

@@ -1,6 +1,6 @@
 parser_test262 Summary:
-AST Parsed     : 44226/44226 (100.00%)
-Positive Passed: 44226/44226 (100.00%)
+AST Parsed     : 44219/44219 (100.00%)
+Positive Passed: 44219/44219 (100.00%)
 Negative Passed: 3919/3947 (99.29%)
 Expect Syntax Error: "built-ins/RegExp/prototype/unicodeSets/breaking-change-from-u-to-v-01.js"
 Expect Syntax Error: "built-ins/RegExp/prototype/unicodeSets/breaking-change-from-u-to-v-02.js"

tasks/coverage/parser_test262.snap

@@ -1,7 +1,7 @@
 parser_typescript Summary:
-AST Parsed     : 5065/5069 (99.92%)
-Positive Passed: 5056/5069 (99.74%)
-Negative Passed: 989/4751 (20.82%)
+AST Parsed     : 5068/5071 (99.94%)
+Positive Passed: 5059/5071 (99.76%)
+Negative Passed: 986/4751 (20.75%)
 Expect Syntax Error: "compiler/ClassDeclaration10.ts"
 Expect Syntax Error: "compiler/ClassDeclaration11.ts"
 Expect Syntax Error: "compiler/ClassDeclaration13.ts"
@@ -79,6 +79,7 @@ Expect Syntax Error: "compiler/argumentsPropertyNameInJsMode1.ts"
 Expect Syntax Error: "compiler/argumentsReferenceInConstructor4_Js.ts"
 Expect Syntax Error: "compiler/argumentsReferenceInMethod4_Js.ts"
 Expect Syntax Error: "compiler/argumentsReferenceInObjectLiteral_Js.ts"
+Expect Syntax Error: "compiler/argumentsSpreadRestIterables.tsx"
 Expect Syntax Error: "compiler/arithAssignTyping.ts"
 Expect Syntax Error: "compiler/arithmeticOnInvalidTypes.ts"
 Expect Syntax Error: "compiler/arithmeticOnInvalidTypes2.ts"
@@ -1567,6 +1568,7 @@ Expect Syntax Error: "compiler/strictNullEmptyDestructuring.ts"
 Expect Syntax Error: "compiler/strictNullNotNullIndexTypeNoLib.ts"
 Expect Syntax Error: "compiler/strictOptionalProperties1.ts"
 Expect Syntax Error: "compiler/strictOptionalProperties3.ts"
+Expect Syntax Error: "compiler/strictSubtypeAndNarrowing.ts"
 Expect Syntax Error: "compiler/stringIndexerAndConstructor.ts"
 Expect Syntax Error: "compiler/stringIndexerAndConstructor1.ts"
 Expect Syntax Error: "compiler/stringIndexerAssignments1.ts"
@@ -3617,6 +3619,7 @@ Expect Syntax Error: "conformance/types/typeParameters/typeParameterAsBaseType.t
 Expect Syntax Error: "conformance/types/typeParameters/typeParameterLists/propertyAccessOnTypeParameterWithConstraints4.ts"
 Expect Syntax Error: "conformance/types/typeParameters/typeParameterLists/propertyAccessOnTypeParameterWithConstraints5.ts"
 Expect Syntax Error: "conformance/types/typeParameters/typeParameterLists/staticMembersUsingClassTypeParameter.ts"
+Expect Syntax Error: "conformance/types/typeParameters/typeParameterLists/typeParameterConstModifiers.ts"
 Expect Syntax Error: "conformance/types/typeParameters/typeParameterLists/typeParameterDirectlyConstrainedToItself.ts"
 Expect Syntax Error: "conformance/types/typeParameters/typeParameterLists/typeParameterIndirectlyConstrainedToItself.ts"
 Expect Syntax Error: "conformance/types/typeParameters/typeParameterLists/typesWithDuplicateTypeParameters.ts"
@@ -3798,15 +3801,6 @@ Expect to Parse: "compiler/emitBundleWithShebangAndPrologueDirectives1.ts"
  7 │ "use strict"
    ╰────
 
-Expect to Parse: "compiler/spreadsAndContextualTupleTypes.ts"
-  × Unexpected token
-    ╭─[compiler/spreadsAndContextualTupleTypes.ts:26:1]
- 26 │ 
- 27 │ declare function foo<const T>(path: T): T;
-    ·                      ─────
- 28 │ 
-    ╰────
-
 Expect to Parse: "compiler/withStatementInternalComments.ts"
   × 'with' statements are not allowed
    ╭─[compiler/withStatementInternalComments.ts:1:1]
@@ -4075,14 +4069,6 @@ Expect to Parse: "conformance/salsa/plainJSRedeclare3.ts"
    ·                         ╰── `:` expected
    ╰────
 
-  × Unexpected token
-    ╭─[compiler/argumentsSpreadRestIterables.tsx:10:1]
- 10 │ 
- 11 │ declare function fn1<const T extends readonly unknown[]>(...args: T): T;
-    ·                      ─────
- 12 │ const res1 = fn1(..."hello");
-    ╰────
-
   × 'arguments' is not allowed in class field initializer
    ╭─[compiler/argumentsUsedInClassFieldInitializerOrStaticInitializationBlock.ts:2:1]
  2 │   return class T {
@@ -8568,14 +8554,6 @@ Expect to Parse: "conformance/salsa/plainJSRedeclare3.ts"
    ·        ──────
    ╰────
 
-  × Unexpected token
-     ╭─[compiler/strictSubtypeAndNarrowing.ts:187:1]
- 187 │     ObjT extends object,
- 188 │     const DeepPathT extends ReadonlyArray<number | string>,
-     ·     ─────
- 189 │     ValueT,
-     ╰────
-
   × Unterminated string
    ╭─[compiler/stringLiteralsErrors.ts:1:1]
  1 │ // Srtings missing line terminator
@@ -19046,14 +19024,6 @@ Expect to Parse: "conformance/salsa/plainJSRedeclare3.ts"
  22 │ const a9 = (f<number>)<number>;  // Error, no applicable signatures
     ╰────
 
-  × Unexpected token
-   ╭─[conformance/types/typeParameters/typeParameterLists/typeParameterConstModifiers.ts:2:1]
- 2 │ 
- 3 │ declare function f1<const T>(x: T): T;
-   ·                     ─────
- 4 │ 
-   ╰────
-
   × Expected `,` but found `Identifier`
     ╭─[conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts:97:1]
  97 │