Prevent explosion of types which turns into over-generalization

Author: staabm

src/Type/Constant/ConstantArrayType.php

@@ -699,7 +699,7 @@ public function getOffsetValueType(Type $offsetType): Type
 
 	public function setOffsetValueType(?Type $offsetType, Type $valueType, bool $unionValues = true): Type
 	{
-		if ($offsetType !== null) {
+		if ($offsetType !== null && $valueType->isConstantScalarValue()->yes()) {
 			$constantScalars = $offsetType->getConstantScalarTypes();
 			$constantScalarsCount = count($constantScalars);
 			if ($constantScalarsCount > 1 && $constantScalarsCount < ConstantArrayTypeBuilder::ARRAY_COUNT_LIMIT) {
@@ -721,17 +721,19 @@ public function setOffsetValueType(?Type $offsetType, Type $valueType, bool $uni
 
 	public function setExistingOffsetValueType(Type $offsetType, Type $valueType): Type
 	{
-		$constantScalars = $offsetType->getConstantScalarTypes();
-		$constantScalarsCount = count($constantScalars);
-		if ($constantScalarsCount > 1 && $constantScalarsCount < ConstantArrayTypeBuilder::ARRAY_COUNT_LIMIT) {
-			$arrays = [];
-			foreach ($constantScalars as $constantScalar) {
-				$builder = ConstantArrayTypeBuilder::createFromConstantArray($this);
-				$builder->setOffsetValueType($constantScalar, $valueType);
-				$arrays[] = $builder->getArray();
-			}
+		if ($valueType->isConstantScalarValue()->yes()) {
+			$constantScalars = $offsetType->getConstantScalarTypes();
+			$constantScalarsCount = count($constantScalars);
+			if ($constantScalarsCount > 1 && $constantScalarsCount < ConstantArrayTypeBuilder::ARRAY_COUNT_LIMIT) {
+				$arrays = [];
+				foreach ($constantScalars as $constantScalar) {
+					$builder = ConstantArrayTypeBuilder::createFromConstantArray($this);
+					$builder->setOffsetValueType($constantScalar, $valueType);
+					$arrays[] = $builder->getArray();
+				}
 
-			return TypeCombinator::union(...$arrays);
+				return TypeCombinator::union(...$arrays);
+			}
 		}
 
 		$builder = ConstantArrayTypeBuilder::createFromConstantArray($this);

tests/PHPStan/Analyser/nsrt/constant-array-type-set.php

@@ -21,7 +21,7 @@ public function doFoo(int $i)
 		/** @var 0|1|2 $offset */
 		$offset = doFoo();
 		$c[$offset] = true;
-		assertType('array{bool, bool, bool}', $c);
+		assertType('array{false, false, true}|array{false, true, false}|array{true, false, false}', $c);
 
 		$d = [false, false, false];
 		/** @var int<0, 2> $offset2 */
@@ -33,13 +33,13 @@ public function doFoo(int $i)
 		/** @var 0|1|2|3 $offset3 */
 		$offset3 = doFoo();
 		$e[$offset3] = true;
-		assertType('array{0: bool, 1: bool, 2: bool, 3?: true}', $e);
+		assertType('array{false, false, false, true}|array{false, false, true}|array{false, true, false}|array{true, false, false}', $e);
 
 		$f = [false, false, false];
 		/** @var 0|1 $offset4 */
 		$offset4 = doFoo();
 		$f[$offset4] = true;
-		assertType('array{bool, bool, false}', $f);
+		assertType('array{false, true, false}|array{true, false, false}', $f);
 	}
 
 	/**
@@ -101,7 +101,7 @@ public function doBar6(bool $offset): void
 	{
 		$a = [false, false, false];
 		$a[$offset] = true;
-		assertType('array{bool, bool, false}', $a);
+		assertType('array{false, true, false}|array{true, false, false}', $a);
 	}
 
 	/**