Return never from sealed ObjectType::tryRemove() when a removed union member is a supertype, and from TemplateType::tryRemove() when the bound is emptied

src/Type/Generic/TemplateTypeTrait.php

@@ -409,6 +409,9 @@ public function tryRemove(Type $typeToRemove): ?Type
 		if ($this->getBound() === $bound || $this->getBound()->equals($bound)) {
 			return null;
 		}
+		if ($bound instanceof NeverType) {
+			return $bound;
+		}
 
 		return TemplateTypeFactory::create(
 			$this->getScope(),

src/Type/ObjectType.php

@@ -2094,6 +2094,9 @@ public function tryRemove(Type $typeToRemove): ?Type
 			// time, without rebuilding the subtracted union once per member.
 			$membersToRemove = [];
 			foreach ($typeToRemove->getTypes() as $member) {
+				if ($member->isSuperTypeOf($this)->yes()) {
+					return new NeverType();
+				}
 				$isSuperTypeOfMember = $this->isSuperTypeOf($member);
 				if ($isSuperTypeOfMember->yes()) {
 					$membersToRemove[] = $member;

tests/PHPStan/Rules/Exceptions/ThrowsVoidFunctionWithExplicitThrowPointRuleTest.php

@@ -104,4 +104,11 @@ public function testBug13515(): void
 		$this->analyse([__DIR__ . '/data/bug-13515.php'], []);
 	}
 
+	public function testBug15392(): void
+	{
+		$this->missingCheckedExceptionInThrows = false;
+		$this->checkedExceptionClasses = [];
+		$this->analyse([__DIR__ . '/data/bug-15392.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Exceptions/data/bug-15392.php

@@ -0,0 +1,33 @@
+<?php declare(strict_types = 1);
+
+namespace Bug15392;
+
+/** @phpstan-sealed SubA|SubB */
+abstract class BaseEx extends \RuntimeException {}
+final class SubA extends BaseEx {}
+final class SubB extends BaseEx {}
+final class OtherEx extends \RuntimeException {}
+
+/** @throws BaseEx */
+function process(): void
+{
+	throw new SubA();
+}
+
+/** @throws void */
+function g(): void
+{
+	try {
+		process();
+	} catch (BaseEx | OtherEx $e) {
+	}
+}
+
+/** @throws void */
+function h(): void
+{
+	try {
+		process();
+	} catch (OtherEx | BaseEx $e) {
+	}
+}

tests/PHPStan/Type/TypeCombinatorTest.php

@@ -6530,6 +6530,47 @@ public static function dataRemove(): array
 				IntersectionType::class,
 				'non-empty-array&hasOffsetValue(\'a\', string)',
 			],
+			[
+				new ObjectType('PHPStan\Fixture\TestEnum'),
+				new UnionType([
+					new ObjectType('PHPStan\Fixture\TestEnum'),
+					new ObjectType(stdClass::class),
+				]),
+				NeverType::class,
+				'*NEVER*=implicit',
+			],
+			[
+				new ObjectType('PHPStan\Fixture\TestEnum'),
+				new UnionType([
+					new ObjectType(stdClass::class),
+					new ObjectType('PHPStan\Fixture\TestEnumInterface'),
+				]),
+				NeverType::class,
+				'*NEVER*=implicit',
+			],
+			[
+				new ObjectType('PHPStan\Fixture\TestEnum'),
+				new UnionType([
+					new ObjectType(stdClass::class),
+					new ObjectType('PHPStan\Fixture\TestEnum'),
+				]),
+				NeverType::class,
+				'*NEVER*=implicit',
+			],
+			[
+				TemplateTypeFactory::create(
+					TemplateTypeScope::createWithFunction('a'),
+					'T',
+					new ObjectType('PHPStan\Fixture\TestEnum'),
+					TemplateTypeVariance::createInvariant(),
+				),
+				new UnionType([
+					new ObjectType('PHPStan\Fixture\TestEnum'),
+					new ObjectType(stdClass::class),
+				]),
+				NeverType::class,
+				'*NEVER*=implicit',
+			],
 		];
 	}
 

turbo-ext/src/ObjectType.cpp

@@ -2799,6 +2799,14 @@ class ObjectType
 						zend_type_error("phpstan_turbo: a union member must be %s", ptcls::type);
 						return zv::Val();
 					}
+					/* if ($member->isSuperTypeOf($this)->yes()) return new NeverType(); */
+					zval selfZv;
+					ZVAL_OBJ(&selfZv, self);
+					zv::Val memberIsSuperType = pt_type_call(Z_OBJ_P(member), PT_LC("issupertypeof"), 1, &selfZv);
+					if (UNEXPECTED(memberIsSuperType.isUndef())) return zv::Val();
+					zend_long memberIsSuperTypeValue = pt_type_result_trinary(memberIsSuperType.raw());
+					if (UNEXPECTED(memberIsSuperTypeValue < 0)) return zv::Val();
+					if (memberIsSuperTypeValue == PT_TRI_YES) return pt_type_new_never_type();
 					zv::Val isSuperTypeOfMember = thisCall(PT_LC("issupertypeof"), otIsSuperTypeOf, 1, member, [&]() { return isSuperTypeOf(member); });
 					if (UNEXPECTED(isSuperTypeOfMember.isUndef())) return zv::Val();
 					zend_long memberValue = pt_type_result_trinary(isSuperTypeOfMember.raw());

turbo-ext/src/TypeTraits.cpp

@@ -4705,6 +4705,8 @@ class TemplateTypeTrait
 		zv::Val equal = pt_type_op(Z_OBJ_P(boundOnceMore.raw()), PT_OP_EQUALS, 1, removed.raw());
 		if (UNEXPECTED(equal.isUndef())) return zv::Val();
 		if (zend_is_true(equal.raw())) return zv::Val::null();
+		/* if ($bound instanceof NeverType) return $bound; */
+		if (zv::Ref(removed.raw()).instanceOf(pt_ce_never_type)) return removed;
 		return recreateKeepingDefault(removed.raw());
 	}