Prevent Scalar expressions to be specified

src/Analyser/MutatingScope.php

@@ -24,6 +24,7 @@
 use PhpParser\Node\Name;
 use PhpParser\Node\Name\FullyQualified;
 use PhpParser\Node\PropertyHook;
+use PhpParser\Node\Scalar;
 use PhpParser\Node\Scalar\String_;
 use PhpParser\Node\Stmt\ClassMethod;
 use PhpParser\Node\Stmt\Function_;
@@ -3946,6 +3947,9 @@ public function enterMatch(Expr\Match_ $expr): self
 		} else {
 			$cond = $expr->cond;
 		}
+		if ($cond instanceof Scalar) {
+			return $this;
+		}
 
 		$type = $this->getType($cond);
 		$nativeType = $this->getNativeType($cond);
@@ -4265,6 +4269,10 @@ private function unsetExpression(Expr $expr): self
 
 	public function specifyExpressionType(Expr $expr, Type $type, Type $nativeType, TrinaryLogic $certainty): self
 	{
+		if ($expr instanceof Scalar) {
+			return $this;
+		}
+
 		if ($expr instanceof ConstFetch) {
 			$loweredConstName = strtolower($expr->name->toString());
 			if (in_array($loweredConstName, ['true', 'false', 'null'], true)) {

tests/PHPStan/Rules/Debug/DebugScopeRuleTest.php

@@ -53,4 +53,17 @@ public function testRuleInPhpStanNamespace(): void
 		]);
 	}
 
+	public function testPr4663(): void
+	{
+		$this->analyse([__DIR__ . '/data/pr-4663.php'], [
+			[
+				implode("\n", [
+					"\$result (Yes): 'no matches!'",
+					"native \$result (Yes): 'no matches!'",
+				]),
+				11,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Debug/data/pr-4663.php

@@ -0,0 +1,12 @@
+<?php declare(strict_types = 1); // lint >= 8.1
+
+namespace PR4663;
+
+use function PHPStan\debugScope;
+
+function (): void {
+	$result = match(1){
+		default => 'no matches!'
+	};
+	debugScope();
+};