fix(noUnusedVariables): don't report params in contructor types

CHANGELOG.md

@@ -59,6 +59,16 @@ our [guidelines for writing a good changelog entry](https://github.com/biomejs/b
 
 - [noEmptyInterface](https://biomejs.dev/linter/rules/no-empty-interface/) now ignores empty interfaces in ambient modules ([#3110](https://github.com/biomejs/biome/issues/3110)). Contributed by @Conaclos
 
+- [noUnusedVariables](https://biomejs.dev/linter/rules/no-unused-variables/) and [noUnusedFunctionParameters](https://biomejs.dev/linter/rules/no-unused-function-parameters/) no longer report the parameters of a constructor type ([#3135](https://github.com/biomejs/biome/issues/3135)).
+
+  Previously, `arg` was reported as unused in a constructor type like:
+
+  ```ts
+  export type Classlike = new (arg: unknown) => string;
+  ```
+
+  Contributed by @Conaclos
+
 ### Parser
 
 #### New features

crates/biome_js_analyze/src/lint/correctness/no_unused_variables.rs

@@ -7,7 +7,7 @@ use biome_analyze::{
 use biome_console::markup;
 use biome_js_semantic::ReferencesExtensions;
 use biome_js_syntax::binding_ext::{
-    AnyJsBindingDeclaration, AnyJsIdentifierBinding, JsAnyParameterParentFunction,
+    AnyJsBindingDeclaration, AnyJsIdentifierBinding, AnyJsParameterParentFunction,
 };
 use biome_js_syntax::declaration_ext::is_in_ambient_context;
 use biome_js_syntax::{
@@ -114,23 +114,26 @@ pub enum SuggestedFix {
 }
 
 fn is_function_that_is_ok_parameter_not_be_used(
-    parent_function: &Option<JsAnyParameterParentFunction>,
+    parent_function: &Option<AnyJsParameterParentFunction>,
 ) -> bool {
     matches!(
         parent_function,
         Some(
             // bindings in signatures are ok to not be used
-            JsAnyParameterParentFunction::TsMethodSignatureClassMember(_)
-            | JsAnyParameterParentFunction::TsCallSignatureTypeMember(_)
-            | JsAnyParameterParentFunction::TsConstructSignatureTypeMember(_)
-            | JsAnyParameterParentFunction::TsConstructorSignatureClassMember(_)
-            | JsAnyParameterParentFunction::TsMethodSignatureTypeMember(_)
-            | JsAnyParameterParentFunction::TsSetterSignatureClassMember(_)
-            | JsAnyParameterParentFunction::TsSetterSignatureTypeMember(_)
+            AnyJsParameterParentFunction::TsMethodSignatureClassMember(_)
+            | AnyJsParameterParentFunction::TsCallSignatureTypeMember(_)
+            | AnyJsParameterParentFunction::TsConstructSignatureTypeMember(_)
+            | AnyJsParameterParentFunction::TsConstructorSignatureClassMember(_)
+            | AnyJsParameterParentFunction::TsMethodSignatureTypeMember(_)
+            | AnyJsParameterParentFunction::TsSetterSignatureClassMember(_)
+            | AnyJsParameterParentFunction::TsSetterSignatureTypeMember(_)
+            | AnyJsParameterParentFunction::TsIndexSignatureClassMember(_)
             // bindings in function types are ok to not be used
-            | JsAnyParameterParentFunction::TsFunctionType(_)
+            | AnyJsParameterParentFunction::TsFunctionType(_)
+            | AnyJsParameterParentFunction::TsConstructorType(_)
             // binding in declare are ok to not be used
-            | JsAnyParameterParentFunction::TsDeclareFunctionDeclaration(_)
+            | AnyJsParameterParentFunction::TsDeclareFunctionDeclaration(_)
+            | AnyJsParameterParentFunction::TsDeclareFunctionExportDefaultDeclaration(_)
         )
     )
 }
@@ -285,10 +288,8 @@ impl Rule for NoUnusedVariables {
         }
 
         let binding = ctx.query();
-        let name = binding.name_token().ok()?;
-        let name = name.text_trimmed();
 
-        if name.starts_with('_') {
+        if binding.name_token().ok()?.text_trimmed().starts_with('_') {
             return None;
         }
 

crates/biome_js_analyze/src/lint/nursery/no_unused_function_parameters.rs

@@ -4,7 +4,7 @@ use biome_analyze::{
 use biome_console::markup;
 use biome_js_semantic::ReferencesExtensions;
 use biome_js_syntax::{
-    binding_ext::{AnyJsBindingDeclaration, JsAnyParameterParentFunction},
+    binding_ext::{AnyJsBindingDeclaration, AnyJsParameterParentFunction},
     JsIdentifierBinding,
 };
 use biome_rowan::{AstNode, BatchMutationExt};
@@ -65,23 +65,26 @@ pub enum SuggestedFix {
 }
 
 fn is_function_that_is_ok_parameter_not_be_used(
-    parent_function: &Option<JsAnyParameterParentFunction>,
+    parent_function: &Option<AnyJsParameterParentFunction>,
 ) -> bool {
     matches!(
         parent_function,
         Some(
             // bindings in signatures are ok to not be used
-            JsAnyParameterParentFunction::TsMethodSignatureClassMember(_)
-            | JsAnyParameterParentFunction::TsCallSignatureTypeMember(_)
-            | JsAnyParameterParentFunction::TsConstructSignatureTypeMember(_)
-            | JsAnyParameterParentFunction::TsConstructorSignatureClassMember(_)
-            | JsAnyParameterParentFunction::TsMethodSignatureTypeMember(_)
-            | JsAnyParameterParentFunction::TsSetterSignatureClassMember(_)
-            | JsAnyParameterParentFunction::TsSetterSignatureTypeMember(_)
+            AnyJsParameterParentFunction::TsMethodSignatureClassMember(_)
+            | AnyJsParameterParentFunction::TsCallSignatureTypeMember(_)
+            | AnyJsParameterParentFunction::TsConstructSignatureTypeMember(_)
+            | AnyJsParameterParentFunction::TsConstructorSignatureClassMember(_)
+            | AnyJsParameterParentFunction::TsMethodSignatureTypeMember(_)
+            | AnyJsParameterParentFunction::TsSetterSignatureClassMember(_)
+            | AnyJsParameterParentFunction::TsSetterSignatureTypeMember(_)
+            | AnyJsParameterParentFunction::TsIndexSignatureClassMember(_)
             // bindings in function types are ok to not be used
-            | JsAnyParameterParentFunction::TsFunctionType(_)
+            | AnyJsParameterParentFunction::TsFunctionType(_)
+            | AnyJsParameterParentFunction::TsConstructorType(_)
             // binding in declare are ok to not be used
-            | JsAnyParameterParentFunction::TsDeclareFunctionDeclaration(_)
+            | AnyJsParameterParentFunction::TsDeclareFunctionDeclaration(_)
+            | AnyJsParameterParentFunction::TsDeclareFunctionExportDefaultDeclaration(_)
         )
     )
 }

crates/biome_js_analyze/tests/specs/correctness/noUnusedVariables/validType.ts

@@ -0,0 +1 @@
+export type Classlike = new (arg: unknown) => string;

crates/biome_js_analyze/tests/specs/correctness/noUnusedVariables/validType.ts.snap

@@ -0,0 +1,8 @@
+---
+source: crates/biome_js_analyze/tests/spec_tests.rs
+expression: validType.ts
+---
+# Input
+```ts
+export type Classlike = new (arg: unknown) => string;
+```

crates/biome_js_analyze/tests/specs/nursery/noUnusedFunctionParameters/valid.ts

@@ -0,0 +1 @@
+type Classlike = new (arg: unknown) => string;

crates/biome_js_analyze/tests/specs/nursery/noUnusedFunctionParameters/valid.ts.snap

@@ -0,0 +1,8 @@
+---
+source: crates/biome_js_analyze/tests/spec_tests.rs
+expression: valid.ts
+---
+# Input
+```ts
+type Classlike = new (arg: unknown) => string;
+```

crates/biome_js_syntax/src/binding_ext.rs

@@ -410,7 +410,7 @@ impl TsIdentifierBinding {
 }
 
 declare_node_union! {
-    pub JsAnyParameterParentFunction =
+    pub AnyJsParameterParentFunction =
         JsFunctionDeclaration
         | JsFunctionExpression
         | JsArrowFunctionExpression
@@ -440,41 +440,41 @@ declare_node_union! {
         | TsCallSignatureTypeMember
 }
 
-fn parent_function(node: &JsSyntaxNode) -> Option<JsAnyParameterParentFunction> {
+fn parent_function(node: &JsSyntaxNode) -> Option<AnyJsParameterParentFunction> {
     let parent = node.parent()?;
 
     match parent.kind() {
         JsSyntaxKind::JS_PARAMETER_LIST => {
             // SAFETY: kind check above
             let parameters = JsParameterList::unwrap_cast(parent).parent::<JsParameters>()?;
             let parent = parameters.syntax.parent()?;
-            JsAnyParameterParentFunction::cast(parent)
+            AnyJsParameterParentFunction::cast(parent)
         }
         JsSyntaxKind::JS_CONSTRUCTOR_PARAMETER_LIST => {
             // SAFETY: kind check above
             let parameters = JsConstructorParameterList::unwrap_cast(parent)
                 .parent::<JsConstructorParameters>()?;
             let parent = parameters.syntax().parent()?;
-            JsAnyParameterParentFunction::cast(parent)
+            AnyJsParameterParentFunction::cast(parent)
         }
-        _ => JsAnyParameterParentFunction::cast(parent),
+        _ => AnyJsParameterParentFunction::cast(parent),
     }
 }
 
 impl JsFormalParameter {
-    pub fn parent_function(&self) -> Option<JsAnyParameterParentFunction> {
+    pub fn parent_function(&self) -> Option<AnyJsParameterParentFunction> {
         parent_function(&self.syntax)
     }
 }
 
 impl JsRestParameter {
-    pub fn parent_function(&self) -> Option<JsAnyParameterParentFunction> {
+    pub fn parent_function(&self) -> Option<AnyJsParameterParentFunction> {
         parent_function(&self.syntax)
     }
 }
 
 impl TsPropertyParameter {
-    pub fn parent_function(&self) -> Option<JsAnyParameterParentFunction> {
+    pub fn parent_function(&self) -> Option<AnyJsParameterParentFunction> {
         parent_function(&self.syntax)
     }
 }