Understand == between ConstantScalarType

Author: ondrejmirtes

src/Analyser/MutatingScope.php

@@ -2358,6 +2358,10 @@ private function resolveEqualType(Type $leftType, Type $rightType): BooleanType
 			return $this->resolveIdenticalType($leftType, $rightType);
 		}
 
+		if ($leftType instanceof ConstantScalarType && $rightType instanceof ConstantScalarType) {
+			return new ConstantBooleanType($leftType->getValue() == $rightType->getValue()); // phpcs:ignore
+		}
+
 		if ($leftType instanceof ConstantArrayType && $rightType instanceof ConstantArrayType) {
 			return $this->resolveConstantArrayTypeComparison($leftType, $rightType, fn ($leftValueType, $rightValueType): BooleanType => $this->resolveEqualType($leftValueType, $rightValueType));
 		}

tests/PHPStan/Analyser/data/constant-array-type-identical.php

@@ -15,8 +15,8 @@ public function doFoo(string $s): void
 		assertType('false', [1] != [1]);
 		assertType('false', [1] == [2]);
 		assertType('true', [1] != [2]);
-		assertType('bool', [1] == ["1"]);
-		assertType('bool', [1] != ["1"]);
+		assertType('true', [1] == ["1"]);
+		assertType('false', [1] != ["1"]);
 
 		assertType('false', [1] === [2]);
 		assertType('false', [1] !== [1]);

tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeMethodCallRuleEqualsTest.php

@@ -92,6 +92,14 @@ public function testRule(): void
 				'Call to method ImpossibleMethodCall\Foo::isNotSame() with array{1, 3} and array{1, 3} will always evaluate to false.',
 				122,
 			],
+			[
+				'Call to method ImpossibleMethodCall\Foo::isSame() with array{\'a\', \'b\'} and array{1, 2} will always evaluate to false.',
+				139,
+			],
+			[
+				'Call to method ImpossibleMethodCall\Foo::isNotSame() with array{\'a\', \'b\'} and array{1, 2} will always evaluate to true.',
+				142,
+			],
 			[
 				'Call to method ImpossibleMethodCall\Foo::isSame() with \'\' and \'\' will always evaluate to true.',
 				174,