From 17d66a1d4cf13c745dc19416d24138a01749cef4 Mon Sep 17 00:00:00 2001
From: Daiki Nishikawa <nd.12021218@gmail.com>
Date: Mon, 10 Jul 2023 21:16:57 +0900
Subject: [PATCH] fix(rome_js_analyze): skip `this` reference identifier in the
 semantic analyzer (#4675)

---
 CHANGELOG.md                                  |  4 ++++
 .../noUndeclaredVariables.ts                  | 13 ++++++++++++-
 .../noUndeclaredVariables.ts.snap             | 19 ++++++++++++++++---
 crates/rome_js_semantic/src/events.rs         |  4 ++++
 4 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6eb46e4efb5..0485a7666d2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -272,6 +272,10 @@ 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:
diff --git a/crates/rome_js_analyze/tests/specs/correctness/noUndeclaredVariables/noUndeclaredVariables.ts b/crates/rome_js_analyze/tests/specs/correctness/noUndeclaredVariables/noUndeclaredVariables.ts
index 353e59722e2..97ab9fda490 100644
--- a/crates/rome_js_analyze/tests/specs/correctness/noUndeclaredVariables/noUndeclaredVariables.ts
+++ b/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}`
\ No newline at end of file
+export type Invalid<S extends number> = `Hello ${T}`
diff --git a/crates/rome_js_analyze/tests/specs/correctness/noUndeclaredVariables/noUndeclaredVariables.ts.snap b/crates/rome_js_analyze/tests/specs/correctness/noUndeclaredVariables/noUndeclaredVariables.ts.snap
index 832a398abe2..b0621477a65 100644
--- a/crates/rome_js_analyze/tests/specs/correctness/noUndeclaredVariables/noUndeclaredVariables.ts.snap
+++ b/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 │ 
   
 
 ```
diff --git a/crates/rome_js_semantic/src/events.rs b/crates/rome_js_semantic/src/events.rs
index b3700a4f197..b410cdefe2c 100644
--- a/crates/rome_js_semantic/src/events.rs
+++ b/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),