From a20c69e8df295e52165ed3d65a2cba7038031509 Mon Sep 17 00:00:00 2001
From: TypeScript Bot <ts_bot@rcavanaugh.com>
Date: Fri, 14 Jun 2024 06:51:53 -0700
Subject: [PATCH] =?UTF-8?q?=F0=9F=A4=96=20Pick=20PR=20#58514=20(Fixed=20a?=
 =?UTF-8?q?=20regression=20with=20reporting=20u...)=20into=20release-5.5?=
 =?UTF-8?q?=20(#58841)?=
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Co-authored-by: Mateusz Burzyński <mateuszburzynski@gmail.com>
---
 src/compiler/utilities.ts                     |  7 ++++--
 ...s_potentialPredicateUnusedParam.errors.txt | 10 ++++++++
 ...cals_potentialPredicateUnusedParam.symbols | 13 ++++++++++
 ...Locals_potentialPredicateUnusedParam.types | 24 +++++++++++++++++++
 ...sedLocals_potentialPredicateUnusedParam.ts |  8 +++++++
 5 files changed, 60 insertions(+), 2 deletions(-)
 create mode 100644 tests/baselines/reference/noUnusedLocals_potentialPredicateUnusedParam.errors.txt
 create mode 100644 tests/baselines/reference/noUnusedLocals_potentialPredicateUnusedParam.symbols
 create mode 100644 tests/baselines/reference/noUnusedLocals_potentialPredicateUnusedParam.types
 create mode 100644 tests/cases/compiler/noUnusedLocals_potentialPredicateUnusedParam.ts

diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index c7170af2355a4..a16c2a9bb3b00 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -11439,7 +11439,7 @@ export function createNameResolver({
                     }
                     break;
             }
-            if (isSelfReferenceLocation(location)) {
+            if (isSelfReferenceLocation(location, lastLocation)) {
                 lastSelfReferenceLocation = location;
             }
             lastLocation = location;
@@ -11573,6 +11573,7 @@ export function createNameResolver({
     }
 
     type SelfReferenceLocation =
+        | ParameterDeclaration
         | FunctionDeclaration
         | ClassDeclaration
         | InterfaceDeclaration
@@ -11580,8 +11581,10 @@ export function createNameResolver({
         | TypeAliasDeclaration
         | ModuleDeclaration;
 
-    function isSelfReferenceLocation(node: Node): node is SelfReferenceLocation {
+    function isSelfReferenceLocation(node: Node, lastLocation: Node | undefined): node is SelfReferenceLocation {
         switch (node.kind) {
+            case SyntaxKind.Parameter:
+                return !!lastLocation && lastLocation === (node as ParameterDeclaration).name;
             case SyntaxKind.FunctionDeclaration:
             case SyntaxKind.ClassDeclaration:
             case SyntaxKind.InterfaceDeclaration:
diff --git a/tests/baselines/reference/noUnusedLocals_potentialPredicateUnusedParam.errors.txt b/tests/baselines/reference/noUnusedLocals_potentialPredicateUnusedParam.errors.txt
new file mode 100644
index 0000000000000..929eb5a565a75
--- /dev/null
+++ b/tests/baselines/reference/noUnusedLocals_potentialPredicateUnusedParam.errors.txt
@@ -0,0 +1,10 @@
+noUnusedLocals_potentialPredicateUnusedParam.ts(1,40): error TS6133: 'a' is declared but its value is never read.
+
+
+==== noUnusedLocals_potentialPredicateUnusedParam.ts (1 errors) ====
+    function potentialPredicateUnusedParam(a: unknown) {
+                                           ~
+!!! error TS6133: 'a' is declared but its value is never read.
+      return !!Math.random();
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/noUnusedLocals_potentialPredicateUnusedParam.symbols b/tests/baselines/reference/noUnusedLocals_potentialPredicateUnusedParam.symbols
new file mode 100644
index 0000000000000..3decedaf23158
--- /dev/null
+++ b/tests/baselines/reference/noUnusedLocals_potentialPredicateUnusedParam.symbols
@@ -0,0 +1,13 @@
+//// [tests/cases/compiler/noUnusedLocals_potentialPredicateUnusedParam.ts] ////
+
+=== noUnusedLocals_potentialPredicateUnusedParam.ts ===
+function potentialPredicateUnusedParam(a: unknown) {
+>potentialPredicateUnusedParam : Symbol(potentialPredicateUnusedParam, Decl(noUnusedLocals_potentialPredicateUnusedParam.ts, 0, 0))
+>a : Symbol(a, Decl(noUnusedLocals_potentialPredicateUnusedParam.ts, 0, 39))
+
+  return !!Math.random();
+>Math.random : Symbol(Math.random, Decl(lib.es5.d.ts, --, --))
+>Math : Symbol(Math, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>random : Symbol(Math.random, Decl(lib.es5.d.ts, --, --))
+}
+
diff --git a/tests/baselines/reference/noUnusedLocals_potentialPredicateUnusedParam.types b/tests/baselines/reference/noUnusedLocals_potentialPredicateUnusedParam.types
new file mode 100644
index 0000000000000..090e1ae0fb609
--- /dev/null
+++ b/tests/baselines/reference/noUnusedLocals_potentialPredicateUnusedParam.types
@@ -0,0 +1,24 @@
+//// [tests/cases/compiler/noUnusedLocals_potentialPredicateUnusedParam.ts] ////
+
+=== noUnusedLocals_potentialPredicateUnusedParam.ts ===
+function potentialPredicateUnusedParam(a: unknown) {
+>potentialPredicateUnusedParam : (a: unknown) => boolean
+>                              : ^ ^^       ^^^^^^^^^^^^
+>a : unknown
+>  : ^^^^^^^
+
+  return !!Math.random();
+>!!Math.random() : boolean
+>                : ^^^^^^^
+>!Math.random() : boolean
+>               : ^^^^^^^
+>Math.random() : number
+>              : ^^^^^^
+>Math.random : () => number
+>            : ^^^^^^      
+>Math : Math
+>     : ^^^^
+>random : () => number
+>       : ^^^^^^      
+}
+
diff --git a/tests/cases/compiler/noUnusedLocals_potentialPredicateUnusedParam.ts b/tests/cases/compiler/noUnusedLocals_potentialPredicateUnusedParam.ts
new file mode 100644
index 0000000000000..f711939d6d7b9
--- /dev/null
+++ b/tests/cases/compiler/noUnusedLocals_potentialPredicateUnusedParam.ts
@@ -0,0 +1,8 @@
+// @strict: true
+// @noEmit: true
+// @noUnusedLocals: true
+// @noUnusedParameters: true
+
+function potentialPredicateUnusedParam(a: unknown) {
+  return !!Math.random();
+}