Introduce Scope::getMaybeDefinedVariables

Fixes phpstan/phpstan#11772

Author: ruudk

src/Analyser/MutatingScope.php

@@ -574,6 +574,27 @@ public function getDefinedVariables(): array
 		return $variables;
 	}
 
+	/**
+	 * @api
+	 * @return array<int, string>
+	 */
+	public function getMaybeDefinedVariables(): array
+	{
+		$variables = [];
+		foreach ($this->expressionTypes as $exprString => $holder) {
+			if (!$holder->getExpr() instanceof Variable) {
+				continue;
+			}
+			if (!$holder->getCertainty()->maybe()) {
+				continue;
+			}
+
+			$variables[] = substr($exprString, 1);
+		}
+
+		return $variables;
+	}
+
 	private function isGlobalVariable(string $variableName): bool
 	{
 		return in_array($variableName, self::SUPERGLOBAL_VARIABLES, true);

src/Analyser/Scope.php

@@ -67,6 +67,11 @@ public function canAnyVariableExist(): bool;
 	 */
 	public function getDefinedVariables(): array;
 
+	/**
+	 * @return array<int, string>
+	 */
+	public function getMaybeDefinedVariables(): array;
+
 	public function hasConstant(Name $name): bool;
 
 	public function getPropertyReflection(Type $typeWithProperty, string $propertyName): ?ExtendedPropertyReflection;