Only unwrap cast in comparisons when it is redundant

The cast unwrapping in Smaller/SmallerOrEqual type specifying was
unconditionally unwrapping all casts, which could cause incorrect type
narrowing when the cast is not redundant (e.g. (int) on a string
variable). Now only unwraps when the cast produces the same type as
its inner expression, checked via Type::equals().

Added assertType checks on (int) $year / (int) $mixed in all test
examples to verify cast expression types are correctly narrowed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

src/Analyser/TypeSpecifier.php

@@ -494,11 +494,19 @@ public function specifyTypesInCondition(
 
 			$leftExpr = $expr->left;
 			if ($leftExpr instanceof Expr\Cast) {
-				$leftExpr = $leftExpr->expr;
+				$castedType = $scope->getType($leftExpr);
+				$innerType = $scope->getType($leftExpr->expr);
+				if ($castedType->equals($innerType)) {
+					$leftExpr = $leftExpr->expr;
+				}
 			}
 			$rightExpr = $expr->right;
 			if ($rightExpr instanceof Expr\Cast) {
-				$rightExpr = $rightExpr->expr;
+				$castedType = $scope->getType($rightExpr);
+				$innerType = $scope->getType($rightExpr->expr);
+				if ($castedType->equals($innerType)) {
+					$rightExpr = $rightExpr->expr;
+				}
 			}
 
 			if ($context->true()) {

tests/PHPStan/Analyser/nsrt/bug-7858.php

@@ -10,6 +10,7 @@ function foo(int $year): void
 		throw new \RuntimeException();
 	}
 	assertType('int<2022, max>', $year);
+	assertType('int<2022, max>', (int) $year);
 }
 
 function bar(int $year): void
@@ -25,15 +26,17 @@ function baz($year): void
 	if (!ctype_digit($year) || (int)$year < 2022) {
 		throw new \RuntimeException();
 	}
-	assertType('int<2022, max>|numeric-string', $year);
+	assertType('int<48, 57>|int<256, max>|numeric-string', $year);
+	assertType('int<2022, max>', (int) $year);
 }
 
 function bam(int|string $year): void
 {
 	if (!ctype_digit($year) || (int)$year < 2022) {
 		throw new \RuntimeException();
 	}
-	assertType('int<2022, max>|numeric-string', $year);
+	assertType('int<48, 57>|int<256, max>|numeric-string', $year);
+	assertType('int<2022, max>', (int) $year);
 }
 
 function ban(string $year): void
@@ -42,12 +45,14 @@ function ban(string $year): void
 		throw new \RuntimeException();
 	}
 	assertType('numeric-string', $year);
+	assertType('int<2022, max>', (int) $year);
 }
 
 function bak($mixed): void
 {
 	if (!is_numeric($mixed) || (int)$mixed < 2022) {
 		throw new \RuntimeException();
 	}
-	assertType("float|int<2022, max>|numeric-string", $mixed);
+	assertType("float|int|numeric-string", $mixed);
+	assertType('int<2022, max>', (int) $mixed);
 }