Exclude constant scalar types from TemplateMixedType narrowing in TypeCombinator::intersect()

Constant scalar values like 0, '', '0' should not be narrowed from
`0&T` to `T of 0` — the intersection form is more precise for constants.
Only general scalar types (int, string, float, bool) are narrowed.

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

Author: phpstan-bot

src/Type/TypeCombinator.php

@@ -1403,6 +1403,7 @@ public static function intersect(Type ...$types): Type
 					$types[$j] instanceof TemplateMixedType
 					&& !$types[$i] instanceof TemplateType
 					&& $types[$i]->isScalar()->yes()
+					&& !$types[$i]->isConstantScalarValue()->yes()
 					&& $types[$j]->getBound()->isSuperTypeOf($types[$i])->yes()
 				) {
 					$narrowed = TemplateTypeFactory::create(
@@ -1425,6 +1426,7 @@ public static function intersect(Type ...$types): Type
 					$types[$i] instanceof TemplateMixedType
 					&& !$types[$j] instanceof TemplateType
 					&& $types[$j]->isScalar()->yes()
+					&& !$types[$j]->isConstantScalarValue()->yes()
 					&& $types[$i]->getBound()->isSuperTypeOf($types[$j])->yes()
 				) {
 					$narrowed = TemplateTypeFactory::create(

tests/PHPStan/Analyser/nsrt/bug-4117.php

@@ -34,7 +34,7 @@ public function broken(int $key)
 		if ($item) {
 			assertType("T of mixed~(0|0.0|''|'0'|array{}|false|null) (class Bug4117Types\GenericList, argument)", $item);
 		} else {
-			assertType("T of 0 (class Bug4117Types\GenericList, argument)|T of '' (class Bug4117Types\GenericList, argument)|T of '0' (class Bug4117Types\GenericList, argument)|(T of mixed~null (class Bug4117Types\GenericList, argument)&false)|(0.0&T of mixed~null (class Bug4117Types\GenericList, argument))|(list{}&T of mixed~null (class Bug4117Types\GenericList, argument))|null", $item);
+			assertType("(T of mixed~null (class Bug4117Types\GenericList, argument)&false)|(0.0&T of mixed~null (class Bug4117Types\GenericList, argument))|(0&T of mixed~null (class Bug4117Types\GenericList, argument))|(list{}&T of mixed~null (class Bug4117Types\GenericList, argument))|(''&T of mixed~null (class Bug4117Types\GenericList, argument))|('0'&T of mixed~null (class Bug4117Types\GenericList, argument))|null", $item);
 		}
 
 		assertType('T of mixed~null (class Bug4117Types\GenericList, argument)|null', $item);