fix(js_semantic_model): handle bogus conditional type (#2619)

CHANGELOG.md

@@ -68,9 +68,9 @@ our [guidelines for writing a good changelog entry](https://github.com/biomejs/b
 
 #### Bug fixes
 
-- Fix [noRedeclare](https://biomejs.dev/linter/rules/no-redeclare/) that missed redeclarations in functions ([#2394](https://github.com/biomejs/biome/issues/2394)).
+- [noRedeclare](https://biomejs.dev/linter/rules/no-redeclare/) now reports redeclarations of parameters in a functions body ([#2394](https://github.com/biomejs/biome/issues/2394)).
 
-  The rule was not able to detected redeclaraions of a parameter or a type parameter in the function body.
+  The rule was unable to detect redeclarations of a parameter or type parameter in the function body.
   The following two redeclarations are now reported:
 
   ```ts
@@ -82,7 +82,7 @@ our [guidelines for writing a good changelog entry](https://github.com/biomejs/b
 
   Contributed by @Conaclos
 
-- Fix [noRedeclare](https://biomejs.dev/linter/rules/no-redeclare/) that wrongly reported overloads in object types ([#2608](https://github.com/biomejs/biome/issues/2608)).
+- [noRedeclare](https://biomejs.dev/linter/rules/no-redeclare/) no longer reports overloads in object types ([#2608](https://github.com/biomejs/biome/issues/2608)).
 
   The rule no longer report redeclarations in the following code:
 
@@ -95,7 +95,7 @@ our [guidelines for writing a good changelog entry](https://github.com/biomejs/b
 
   Contributed by @Conaclos
 
-- Fix [noRedeclare](https://biomejs.dev/linter/rules/no-redeclare/) that didn't merge default function export declarations and types ([#2372](https://github.com/biomejs/biome/issues/2372)).
+- [noRedeclare](https://biomejs.dev/linter/rules/no-redeclare/) now merge default function export declarations and types ([#2372](https://github.com/biomejs/biome/issues/2372)).
 
   The following code is no longer reported as a redeclaration:
 
@@ -106,6 +106,9 @@ our [guidelines for writing a good changelog entry](https://github.com/biomejs/b
 
   Contributed by @Conaclos
 
+- [noUnusedVariables] no longer crash Biome when encountering a malformed conditional type ([#1695](https://github.com/biomejs/biome/issues/1695)).
+  Contributed by @Conaclos
+
 - [useConst](https://biomejs.dev/linter/rules/use-const/) now ignores a variable that is read before its assignment.
 
   Previously, the rule reported the following example:
@@ -120,7 +123,7 @@ our [guidelines for writing a good changelog entry](https://github.com/biomejs/b
 
   Contributed by @Conaclos
 
-- Fix [useShorthandFunctionType](https://biomejs.dev/linter/rules/use-shorthand-function-type/) that suggested invalid code fixes when parentheses are required ([#2595](https://github.com/biomejs/biome/issues/2595)).
+- [useShorthandFunctionType](https://biomejs.dev/linter/rules/use-shorthand-function-type/) now suggests correct code fixes when parentheses are required ([#2595](https://github.com/biomejs/biome/issues/2595)).
 
   Previously, the rule didn't add parentheses when they were needed.
   It now adds parentheses when the function signature is inside an array, a union, or an intersection.
@@ -132,7 +135,7 @@ our [guidelines for writing a good changelog entry](https://github.com/biomejs/b
 
   Contributed by @Conaclos
 
-- Fix [useTemplate](https://biomejs.dev/linter/rules/use-template/) that wrongly escaped strings in some edge cases ([#2580](https://github.com/biomejs/biome/issues/2580)).
+- [useTemplate](https://biomejs.dev/linter/rules/use-template/) now correctly escapes strings ([#2580](https://github.com/biomejs/biome/issues/2580)).
 
   Previously, the rule didn't correctly escape characters preceded by an escaped character.
 

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

@@ -0,0 +1 @@
+export type ToPascalCase<S extends string> = S extends `${infer Prefix}` ? : ;

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

@@ -0,0 +1,22 @@
+---
+source: crates/biome_js_analyze/tests/spec_tests.rs
+expression: unusedInferBogusConditional.ts
+---
+# Input
+```ts
+export type ToPascalCase<S extends string> = S extends `${infer Prefix}` ? : ;
+```
+
+# Diagnostics
+```
+unusedInferBogusConditional.ts:1:65 lint/correctness/noUnusedVariables ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! This variable is unused.
+  
+  > 1 │ export type ToPascalCase<S extends string> = S extends `${infer Prefix}` ? : ;
+      │                                                                 ^^^^^^
+  
+  i Unused variables usually are result of incomplete refactoring, typos and other source of bugs.
+  
+
+```

crates/biome_js_semantic/src/events.rs

@@ -366,7 +366,12 @@ impl SemanticEventExtractor {
 
     fn enter_any_type(&mut self, node: &AnyTsType) {
         if node.in_conditional_true_type() {
-            self.push_conditional_true_scope(node);
+            self.push_scope(
+                node.syntax().text_range(),
+                ScopeHoisting::DontHoistDeclarationsToParent,
+                false,
+            );
+            self.push_infers_in_scope();
             return;
         }
         let node = node.syntax();
@@ -668,6 +673,14 @@ impl SemanticEventExtractor {
         ) {
             self.pop_scope(node.text_range());
         }
+        // FALLBACK
+        // If the conditional type has a bogus true type,
+        // then infer declarations was never pushed into any scope.
+        // To ensure that every declaration has a binding,
+        // we bind the declaration directly in the scope of the conditional type.
+        if matches!(node.kind(), JsSyntaxKind::TS_CONDITIONAL_TYPE) && !self.infers.is_empty() {
+            self.push_infers_in_scope()
+        }
     }
 
     /// Return any previous extracted [SemanticEvent].
@@ -676,13 +689,7 @@ impl SemanticEventExtractor {
         self.stash.pop_front()
     }
 
-    fn push_conditional_true_scope(&mut self, node: &AnyTsType) {
-        self.push_scope(
-            node.syntax().text_range(),
-            ScopeHoisting::DontHoistDeclarationsToParent,
-            false,
-        );
-
+    fn push_infers_in_scope(&mut self) {
         let infers = mem::take(&mut self.infers);
         for infer in infers {
             if let Ok(name_token) = infer.ident_token() {