feat(semantic): report type parameter list cannot be empty (#2315)

crates/oxc_semantic/src/checker/typescript.rs

@@ -21,11 +21,27 @@ impl EarlyErrorTypeScript {
             AstKind::SimpleAssignmentTarget(target) => check_simple_assignment_target(target, ctx),
             AstKind::FormalParameters(params) => check_formal_parameters(params, ctx),
             AstKind::ArrayPattern(pattern) => check_array_pattern(pattern, ctx),
+            AstKind::TSTypeParameterDeclaration(declaration) => {
+                check_ts_type_parameter_declaration(declaration, ctx);
+            }
             _ => {}
         }
     }
 }
 
+fn check_ts_type_parameter_declaration(
+    declaration: &TSTypeParameterDeclaration<'_>,
+    ctx: &SemanticBuilder<'_>,
+) {
+    #[derive(Debug, Error, Diagnostic)]
+    #[error("Type parameter list cannot be empty.")]
+    #[diagnostic()]
+    struct EmptyTypeParameterList(#[label] Span);
+    if declaration.params.is_empty() {
+        ctx.error(EmptyTypeParameterList(declaration.span));
+    }
+}
+
 #[allow(clippy::cast_possible_truncation)]
 fn check_variable_declarator(decl: &VariableDeclarator, ctx: &SemanticBuilder<'_>) {
     #[derive(Debug, Error, Diagnostic)]

tasks/coverage/parser_babel.snap

@@ -1,7 +1,7 @@
 parser_babel Summary:
 AST Parsed     : 2090/2096 (99.71%)
 Positive Passed: 2086/2096 (99.52%)
-Negative Passed: 1358/1500 (90.53%)
+Negative Passed: 1360/1500 (90.67%)
 Expect Syntax Error: "annex-b/disabled/1.1-html-comments-close/input.js"
 Expect Syntax Error: "annex-b/disabled/3.1-sloppy-labeled-functions/input.js"
 Expect Syntax Error: "annex-b/disabled/3.1-sloppy-labeled-functions-if-body/input.js"
@@ -61,7 +61,6 @@ Expect Syntax Error: "typescript/class/declare-readonly-field-initializer-w-anno
 Expect Syntax Error: "typescript/class/duplicate-modifier-1/input.ts"
 Expect Syntax Error: "typescript/class/duplicate-modifier-2/input.ts"
 Expect Syntax Error: "typescript/class/duplicates-accessibility/input.ts"
-Expect Syntax Error: "typescript/class/empty-type-parameters/input.ts"
 Expect Syntax Error: "typescript/class/generator-method-with-modifiers/input.ts"
 Expect Syntax Error: "typescript/class/index-signature-errors/input.ts"
 Expect Syntax Error: "typescript/class/invalid-modifiers-order/input.ts"
@@ -92,7 +91,6 @@ Expect Syntax Error: "typescript/expect-plugin/export-type/input.js"
 Expect Syntax Error: "typescript/expect-plugin/export-type-named/input.js"
 Expect Syntax Error: "typescript/export/double-declare/input.ts"
 Expect Syntax Error: "typescript/export/equals-in-script/input.ts"
-Expect Syntax Error: "typescript/function/empty-type-parameters/input.ts"
 Expect Syntax Error: "typescript/import/equals-in-script/input.ts"
 Expect Syntax Error: "typescript/import/equals-require-in-script/input.ts"
 Expect Syntax Error: "typescript/import/export-import-type/input.ts"
@@ -9733,6 +9731,12 @@ Expect to Parse: "typescript/types/const-type-parameters-babel-7/input.ts"
    ╰────
   help: Try insert a semicolon here
 
+  × Type parameter list cannot be empty.
+   ╭─[typescript/class/empty-type-parameters/input.ts:1:8]
+ 1 │ class C<> {}
+   ·        ──
+   ╰────
+
   × Expected `{` but found `EOF`
    ╭─[typescript/class/extends-empty/input.ts:2:1]
  2 │ }
@@ -9880,6 +9884,12 @@ Expect to Parse: "typescript/types/const-type-parameters-babel-7/input.ts"
    ·                ───
    ╰────
 
+  × Type parameter list cannot be empty.
+   ╭─[typescript/function/empty-type-parameters/input.ts:1:13]
+ 1 │ function foo<>() {}
+   ·             ──
+   ╰────
+
   × A parameter property is only allowed in a constructor implementation.
    ╭─[typescript/function/parameter-properties/input.ts:3:3]
  2 │   readonly r,

tasks/coverage/parser_typescript.snap

@@ -1,7 +1,7 @@
 parser_typescript Summary:
 AST Parsed     : 5239/5243 (99.92%)
 Positive Passed: 5232/5243 (99.79%)
-Negative Passed: 1036/4879 (21.23%)
+Negative Passed: 1038/4879 (21.27%)
 Expect Syntax Error: "compiler/ClassDeclaration10.ts"
 Expect Syntax Error: "compiler/ClassDeclaration11.ts"
 Expect Syntax Error: "compiler/ClassDeclaration13.ts"
@@ -306,7 +306,6 @@ Expect Syntax Error: "compiler/classStaticPropertyAccess.ts"
 Expect Syntax Error: "compiler/classTypeParametersInStatics.ts"
 Expect Syntax Error: "compiler/classUsedBeforeInitializedVariables.ts"
 Expect Syntax Error: "compiler/classWithDuplicateIdentifier.ts"
-Expect Syntax Error: "compiler/classWithEmptyTypeParameter.ts"
 Expect Syntax Error: "compiler/classWithMultipleBaseClasses.ts"
 Expect Syntax Error: "compiler/classWithOverloadImplementationOfWrongName.ts"
 Expect Syntax Error: "compiler/classWithOverloadImplementationOfWrongName2.ts"
@@ -3100,7 +3099,6 @@ Expect Syntax Error: "conformance/parser/ecmascript5/ComputedPropertyNames/parse
 Expect Syntax Error: "conformance/parser/ecmascript5/ComputedPropertyNames/parserES5ComputedPropertyName8.ts"
 Expect Syntax Error: "conformance/parser/ecmascript5/ComputedPropertyNames/parserES5ComputedPropertyName9.ts"
 Expect Syntax Error: "conformance/parser/ecmascript5/ConstructorDeclarations/parserConstructorDeclaration10.ts"
-Expect Syntax Error: "conformance/parser/ecmascript5/ConstructorDeclarations/parserConstructorDeclaration11.ts"
 Expect Syntax Error: "conformance/parser/ecmascript5/ConstructorDeclarations/parserConstructorDeclaration2.ts"
 Expect Syntax Error: "conformance/parser/ecmascript5/ConstructorDeclarations/parserConstructorDeclaration4.ts"
 Expect Syntax Error: "conformance/parser/ecmascript5/ConstructorDeclarations/parserConstructorDeclaration6.ts"
@@ -4821,6 +4819,13 @@ Expect to Parse: "conformance/salsa/plainJSRedeclare3.ts"
     ╰────
   help: Try insert a semicolon here
 
+  × Type parameter list cannot be empty.
+   ╭─[compiler/classWithEmptyTypeParameter.ts:1:8]
+ 1 │ class C<> {
+   ·        ──
+ 2 │ }
+   ╰────
+
   × Cannot assign to 'arguments' in strict mode
    ╭─[compiler/collisionArgumentsClassConstructor.ts:3:31]
  2 │ class c1 {
@@ -8148,6 +8153,70 @@ Expect to Parse: "conformance/salsa/plainJSRedeclare3.ts"
    ·  ─
    ╰────
 
+  × Type parameter list cannot be empty.
+   ╭─[compiler/parserConstructorDeclaration12.ts:2:14]
+ 1 │ class C {
+ 2 │   constructor<>() { }
+   ·              ──
+ 3 │   constructor<> () { }
+   ╰────
+
+  × Type parameter list cannot be empty.
+   ╭─[compiler/parserConstructorDeclaration12.ts:3:14]
+ 2 │   constructor<>() { }
+ 3 │   constructor<> () { }
+   ·              ──
+ 4 │   constructor <>() { }
+   ╰────
+
+  × Type parameter list cannot be empty.
+   ╭─[compiler/parserConstructorDeclaration12.ts:4:15]
+ 3 │   constructor<> () { }
+ 4 │   constructor <>() { }
+   ·               ──
+ 5 │   constructor <> () { }
+   ╰────
+
+  × Type parameter list cannot be empty.
+   ╭─[compiler/parserConstructorDeclaration12.ts:5:15]
+ 4 │   constructor <>() { }
+ 5 │   constructor <> () { }
+   ·               ──
+ 6 │   constructor< >() { }
+   ╰────
+
+  × Type parameter list cannot be empty.
+   ╭─[compiler/parserConstructorDeclaration12.ts:6:14]
+ 5 │   constructor <> () { }
+ 6 │   constructor< >() { }
+   ·              ───
+ 7 │   constructor< > () { }
+   ╰────
+
+  × Type parameter list cannot be empty.
+   ╭─[compiler/parserConstructorDeclaration12.ts:7:14]
+ 6 │   constructor< >() { }
+ 7 │   constructor< > () { }
+   ·              ───
+ 8 │   constructor < >() { }
+   ╰────
+
+  × Type parameter list cannot be empty.
+   ╭─[compiler/parserConstructorDeclaration12.ts:8:15]
+ 7 │   constructor< > () { }
+ 8 │   constructor < >() { }
+   ·               ───
+ 9 │   constructor < > () { }
+   ╰────
+
+  × Type parameter list cannot be empty.
+    ╭─[compiler/parserConstructorDeclaration12.ts:9:15]
+  8 │   constructor < >() { }
+  9 │   constructor < > () { }
+    ·               ───
+ 10 │ }
+    ╰────
+
   × Multiple constructor implementations are not allowed.
    ╭─[compiler/parserConstructorDeclaration12.ts:2:3]
  1 │ class C {
@@ -16202,6 +16271,14 @@ Expect to Parse: "conformance/salsa/plainJSRedeclare3.ts"
    ·                 ╰── `,` expected
    ╰────
 
+  × Type parameter list cannot be empty.
+   ╭─[conformance/parser/ecmascript5/ConstructorDeclarations/parserConstructorDeclaration11.ts:2:14]
+ 1 │ class C {
+ 2 │   constructor<>() { }
+   ·              ──
+ 3 │ }
+   ╰────
+
   × Expected a semicolon or an implicit semicolon after a statement, but found none
    ╭─[conformance/parser/ecmascript5/ConstructorDeclarations/parserConstructorDeclaration3.ts:2:9]
  1 │ class C {