fix(rome_js_analyze): skip this reference identifier in the semantic analyzer

CHANGELOG.md

@@ -266,6 +266,10 @@ if no error diagnostics are emitted.
 
   This rule's code action emits an invalid AST, so I fixed using JsxString instead of JsStringLiteral
 
+- Fix [noUndeclaredVariables](https://docs.rome.tools/lint/rules/noundeclaredvariables/)'s false positive diagnostics ([#4675](https://github.com/rome/tools/issues/4675))
+
+  The semantic analyzer no longer handles `this` reference identifier in the semantic analyzer.
+
 ### Parser
 
 - Add support for decorators in class method parameters, example:

crates/rome_js_analyze/tests/specs/correctness/noUndeclaredVariables/noUndeclaredVariables.ts

@@ -11,5 +11,16 @@ export type WhateverDefault<S extends number = 2> = `Hello ${S}`
 // Const assertions are valid
 const fruits = ["banana"] as const;
 
+class X {
+  f() {
+    this.g;
+    type T1 = typeof this.g;
+    type T2 = X['g'];
+  }
+
+  g() {
+  }
+}
+
 // Invalid
-export type Invalid<S extends number> = `Hello ${T}`
+export type Invalid<S extends number> = `Hello ${T}`

crates/rome_js_analyze/tests/specs/correctness/noUndeclaredVariables/noUndeclaredVariables.ts.snap

@@ -17,19 +17,32 @@ export type WhateverDefault<S extends number = 2> = `Hello ${S}`
 // Const assertions are valid
 const fruits = ["banana"] as const;
 
+class X {
+  f() {
+    this.g;
+    type T1 = typeof this.g;
+    type T2 = X['g'];
+  }
+
+  g() {
+  }
+}
+
 // Invalid
 export type Invalid<S extends number> = `Hello ${T}`
+
 ```
 
 # Diagnostics
 ```
-noUndeclaredVariables.ts:15:50 lint/correctness/noUndeclaredVariables ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+noUndeclaredVariables.ts:26:50 lint/correctness/noUndeclaredVariables ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
   ! The T variable is undeclared
 
-    14 │ // Invalid
-  > 15 │ export type Invalid<S extends number> = `Hello ${T}`
+    25 │ // Invalid
+  > 26 │ export type Invalid<S extends number> = `Hello ${T}`
        │                                                  ^
+    27 │ 
 
 
 ```

crates/rome_js_semantic/src/events.rs

@@ -479,6 +479,10 @@ impl SemanticEventExtractor {
                 // SAFETY: kind check above
                 let reference = JsReferenceIdentifier::unwrap_cast(node.clone());
                 let name_token = reference.value_token().ok()?;
+                // skip `this` reference representing the class instance
+                if name_token.token_text_trimmed() == "this" {
+                    return None;
+                }
                 (
                     name_token.token_text_trimmed(),
                     self.is_js_reference_identifier_exported(node),