Add array assertions about unsealed arrays

src/Type/Constant/ConstantArrayType.php

@@ -1523,6 +1523,8 @@ public function flipArray(): Type
 		if ($this->isUnsealed()->yes() && $this->unsealed !== null) {
 			[$unsealedKey, $unsealedValue] = $this->unsealed;
 			$builder->makeUnsealed($unsealedValue->toArrayKey(), $unsealedKey);
+
+			$builder->setOffsetValueType($unsealedValue->toArrayKey(), $unsealedKey, true);
 		}
 
 		return $builder->getArray();

tests/PHPStan/Analyser/nsrt/array-fill-keys.php

@@ -104,3 +104,13 @@ function withNotConstantArray(array $foo, array $bar, array $baz, array $floats,
 		assertType('non-empty-array<bool|int|string, null>', array_fill_keys($mixed, null));
 	}
 }
+
+/**
+ * @param array{0: 1, 1: 2, 2: 3} $sealed
+ * @param array{0: 1, 1: 2, 2: 3, ...<int, bool>} $unsealed
+ */
+function sealedArrayFillKeys(array $sealed, array $unsealed): void
+{
+	assertType("array{1: 'b', 2: 'b', 3: 'b'}", array_fill_keys($sealed, 'b'));
+	assertType("array{1: 'b', 2: 'b', 3: 'b', ...<0|1, 'b'>}", array_fill_keys($unsealed, 'b'));
+}

tests/PHPStan/Analyser/nsrt/array-flip.php

@@ -93,3 +93,14 @@ function foo10(array $array)
 		assertType("*NEVER*", array_flip($array)); // this could be array<string, int>&hasOffsetValue(17, 'bar') according to https://3v4l.org/1TAFk
 	}
 }
+
+/**
+ * @param array{0: 1, 1: 2, 2: 3} $sealed
+ * @param array{0: 1, 1: 2, 2: 3, ...<int, bool>} $unsealed
+ */
+function sealedArrayFlip(array $sealed, array $unsealed): void
+{
+	assertType('array{1: 0, 2: 1, 3: 2}', array_flip($sealed));
+	assertType('array{1: int, 2: 1, 3: 2, 0?: int, ...<0|1, int>}', array_flip($unsealed));
+	assertType('int', array_flip($unsealed)[1]);
+}

tests/PHPStan/Analyser/nsrt/unsealed-derivations.php

@@ -292,7 +292,7 @@ public function flipPreservesUnsealed(array $arr): void
 		// `array_flip` swaps keys and values pair-by-pair, so the
 		// unsealed `<int, string>` becomes `<string, int>` — the value
 		// type passes through `toArrayKey()` to land in the new key slot.
-		assertType("array{foo: 'a', bar: 'b', ...<string, int>}", array_flip($arr));
+		assertType("array{foo: 'a'|int, bar: 'b'|int, ...<string, int>}", array_flip($arr));
 	}
 
 	/**