Skip narrowing for non-constant arrays with multiple possible value types

For non-constant arrays like `non-empty-array<'a'|'b'>`, we cannot
guarantee any specific value is present, so no narrowing should occur
in the false context. Only narrow when the value type has exactly one
finite type (e.g. `non-empty-array<'a'>`).

Added regression test for this case.

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

Author: phpstan-bot

src/Type/Php/InArrayFunctionTypeSpecifyingExtension.php

@@ -203,7 +203,10 @@ private function computeNeedleNarrowingType(TypeSpecifierContext $context, Type
 						: new NeverType();
 				}
 			} else {
-				$innerValueTypes[] = $array->getIterableValueType();
+				$valueType = $array->getIterableValueType();
+				if (count($valueType->getFiniteTypes()) === 1) {
+					$innerValueTypes[] = $valueType;
+				}
 			}
 		}
 

tests/PHPStan/Analyser/nsrt/bug-14407.php

@@ -86,3 +86,15 @@ function testUnionWithOptionalKeys($x, $a): void
 		assertType("'a'|'b'|'c'", $x);
 	}
 };
+
+/**
+ * @param 'a'|'b'|'c' $x
+ * @param non-empty-array<'a'|'b'> $a
+ */
+function testNonConstantArray($x, $a): void
+{
+	assertType("non-empty-array<'a'|'b'>", $a);
+	if (!\in_array($x, $a, true)) {
+		assertType("'a'|'b'|'c'", $x);
+	}
+};