instanceof+interface unexpected narrows to never-arkcompiler_ets

Mets2panda/checker/ets/arithmetic.cpp+1-1

	@@ -1176,7 +1176,7 @@ static void ReportIfInstanceofTrivialKnown(ETSChecker checker, Type lhs, Type
1176	checker->LogDiagnostic(diagnostic::INSTANCEOF_ALWAYS_KNOWN,	1176	checker->LogDiagnostic(diagnostic::INSTANCEOF_ALWAYS_KNOWN,
1177	util::DiagnosticMessageParams {INSTANCEOF_ALWAYS_TRUE_WORD}, pos);	1177	util::DiagnosticMessageParams {INSTANCEOF_ALWAYS_TRUE_WORD}, pos);
1178	}	1178	}
1179	- } else if (!HasInterfaceConstituent(lhs) \|\| !HasInterfaceConstituent(rhs)) {	1179	+ } else if (!HasInterfaceConstituent(lhs) && !HasInterfaceConstituent(rhs)) {
1180	checker->LogDiagnostic(diagnostic::INSTANCEOF_ALWAYS_KNOWN,	1180	checker->LogDiagnostic(diagnostic::INSTANCEOF_ALWAYS_KNOWN,
1181	util::DiagnosticMessageParams {INSTANCEOF_ALWAYS_FALSE_WORD}, pos);	1181	util::DiagnosticMessageParams {INSTANCEOF_ALWAYS_FALSE_WORD}, pos);
1182	}	1182	}

Mets2panda/checker/ets/helpers.cpp+6-0

	@@ -1508,6 +1508,12 @@ std::pair<Type , Type > ETSChecker::CheckTestObjectCondition(ETSObjectType *te
1508	return {testedType, GetGlobalTypesHolder()->GlobalETSNeverType()};	1508	return {testedType, GetGlobalTypesHolder()->GlobalETSNeverType()};
1509	}	1509	}
1510		1510
		1511	+ // When neither type is a supertype of the other, instanceof can still succeed if
		1512	+ // at least one type is an interface.
		1513	+ if (testedType->IsInterface() \|\| objectType->IsInterface()) {
		1514	+ return {testedType, actualType};
		1515	+ }
		1516	+
1511	return {GetGlobalTypesHolder()->GlobalETSNeverType(), actualType};	1517	return {GetGlobalTypesHolder()->GlobalETSNeverType(), actualType};
1512	}	1518	}
1513		1519

Aets2panda/test/ast/compiler/ets/instanceof_interface_narrowing_warn.ets+83-0

@@ -0,0 +1,83 @@
	1	+/**
	2	+ * Copyright (c) 2026 Huawei Device Co., Ltd.
	3	+ * Licensed under the Apache License, Version 2.0 (the "License");
	4	+ * you may not use this file except in compliance with the License.
	5	+ * You may obtain a copy of the License at
	6	+ *
	7	+ * http://www.apache.org/licenses/LICENSE-2.0
	8	+ *
	9	+ * Unless required by applicable law or agreed to in writing, software
	10	+ * distributed under the License is distributed on an "AS IS" BASIS,
	11	+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	12	+ * See the License for the specific language governing permissions and
	13	+ * limitations under the License.
	14	+ */
	15	+
	16	+// Test that instanceof between an interface-typed variable and an unrelated
	17	+// class does NOT produce "always false" warning (W1001506), because a class
	18	+// implementing the interface may also extend the tested class.
	19	+
	20	+interface I {
	21	+ foo(): void
	22	+}
	23	+
	24	+class A {
	25	+ bar(): void {}
	26	+}
	27	+
	28	+class C extends A implements I {
	29	+ foo(): void {}
	30	+}
	31	+
	32	+class D {}
	33	+
	34	+// interface variable instanceof unrelated class — no warning
	35	+function ifaceToClass(i: I): boolean {
	36	+ return i instanceof A
	37	+}
	38	+
	39	+// interface variable instanceof unrelated interface — no warning
	40	+function ifaceToIface(i: I): boolean {
	41	+ return i instanceof D
	42	+}
	43	+
	44	+// class variable instanceof unrelated interface — no warning
	45	+function classToIface(a: A): boolean {
	46	+ return a instanceof I
	47	+}
	48	+
	49	+// class variable instanceof unrelated class — SHOULD warn "always false"
	50	+function classToClass(a: A): boolean {
	51	+ return a instanceof D
	52	+}
	53	+
	54	+// Smart narrowing: after if (i instanceof A), i is narrowed to A,
	55	+// so i instanceof A is "always true"
	56	+function smartNarrowTrue(i: I): boolean {
	57	+ if (i instanceof A) {
	58	+ return i instanceof A
	59	+ }
	60	+ return false
	61	+}
	62	+
	63	+// Smart narrowing: after if (i instanceof A), i is narrowed to A,
	64	+// then i instanceof D (unrelated class to A) is "always false"
	65	+function smartNarrowFalse(i: I): boolean {
	66	+ if (i instanceof A) {
	67	+ return i instanceof D
	68	+ }
	69	+ return false
	70	+}
	71	+
	72	+// Smart narrowing: after if (i instanceof A), i is narrowed to A,
	73	+// then i instanceof I is NOT "always true"
	74	+function smartNarrowBackToIface(i: I): boolean {
	75	+ if (i instanceof A) {
	76	+ return i instanceof I
	77	+ }
	78	+ return false
	79	+}
	80	+
	81	+/* @@? 51:12 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as false */
	82	+/* @@? 58:16 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as true */
	83	+/* @@? 67:16 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as false */

Mets2panda/test/ast/compiler/ets/instanceof_trivial_iface_branch.ets+0-1

	@@ -26,6 +26,5 @@ function qux(x: A): boolean {
26	return false	26	return false
27	}	27	}
28		28
29	-/* @@? 21:17 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as true */
30	/* @@? 22:17 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as true */	29	/* @@? 22:17 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as true */
31	/* @@? 23:17 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as true */	30	/* @@? 23:17 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as true */

Mets2panda/test/ast/compiler/ets/instanceof_trivial_interfaces.ets+0-1

	@@ -48,5 +48,4 @@ function quz(x: C): boolean {
48		48
49	/* @@? 30:12 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as true */	49	/* @@? 30:12 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as true */
50	/* @@? 34:12 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as false */	50	/* @@? 34:12 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as false */
51	-/* @@? 43:21 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as true */
52	/* @@? 44:21 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as true */	51	/* @@? 44:21 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as true */

Mets2panda/test/ast/compiler/ets/instanceof_trivial_smart_narrowing.ets+0-1

	@@ -61,7 +61,6 @@ function quux(x: string \| undefined): number {
61	return x.length + (t1 ? 1 : 0) + (t2 ? 1 : 0)	61	return x.length + (t1 ? 1 : 0) + (t2 ? 1 : 0)
62	}	62	}
63		63
64	-/* @@? 31:9 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as false */
65	/* @@? 32:16 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as true */	64	/* @@? 32:16 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as true */
66	/* @@? 39:16 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as true */	65	/* @@? 39:16 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as true */
67	/* @@? 46:16 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as false */	66	/* @@? 46:16 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as false */

Mets2panda/test/ast/parser/ets/this_type_instanceof_invalid.ets+0-1

	@@ -62,7 +62,6 @@ class C<T> {
62	}	62	}
63		63
64		64
65	-/* @@? 20:8 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as false */
66	/* @@? 20:28 Error Syntax error ESY0130: Invalid right-hand side in 'instanceof' expression. */	65	/* @@? 20:28 Error Syntax error ESY0130: Invalid right-hand side in 'instanceof' expression. */
67	/* @@? 36:9 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as false */	66	/* @@? 36:9 Warning Warning W1001506: the value of the instanceof expression is known at compile-time as false */
68	/* @@? 36:22 Error Syntax error ESY0130: Invalid right-hand side in 'instanceof' expression. */	67	/* @@? 36:22 Error Syntax error ESY0130: Invalid right-hand side in 'instanceof' expression. */

Aets2panda/test/runtime/ets/instanceof_interface_narrowing.ets+133-0

@@ -0,0 +1,133 @@
	1	+/*
	2	+ * Copyright (c) 2026 Huawei Device Co., Ltd.
	3	+ * Licensed under the Apache License, Version 2.0 (the "License");
	4	+ * you may not use this file except in compliance with the License.
	5	+ * You may obtain a copy of the License at
	6	+ *
	7	+ * http://www.apache.org/licenses/LICENSE-2.0
	8	+ *
	9	+ * Unless required by applicable law or agreed to in writing, software
	10	+ * distributed under the License is distributed on an "AS IS" BASIS,
	11	+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	12	+ * See the License for the specific language governing permissions and
	13	+ * limitations under the License.
	14	+ */
	15	+
	16	+interface IBase {
	17	+ getVal(): int
	18	+}
	19	+
	20	+interface IUnrelated {}
	21	+
	22	+class Base {
	23	+ field: int = 0
	24	+}
	25	+
	26	+class Derived extends Base implements IBase {
	27	+ constructor(v: int) {
	28	+ super()
	29	+ this.field = v
	30	+ }
	31	+ getVal(): int {
	32	+ return this.field
	33	+ }
	34	+}
	35	+
	36	+class Other {}
	37	+
	38	+// Case 1: interface variable holding a Derived instance, instanceof a Base class
	39	+function testInterfaceToClass(): int {
	40	+ let i: IBase = new Derived(42)
	41	+ let b: Base
	42	+ try {
	43	+ if (i instanceof Base) {
	44	+ b = i as Base
	45	+ return b.field
	46	+ }
	47	+ } catch (e) {
	48	+ return -1
	49	+ }
	50	+ return -2
	51	+}
	52	+
	53	+// Case 2: interface variable, instanceof an unrelated interface
	54	+function testInterfaceToInterface(): int {
	55	+ let i: IBase = new Derived(10)
	56	+ try {
	57	+ if (i instanceof IUnrelated) {
	58	+ return -1
	59	+ }
	60	+ return i.getVal()
	61	+ } catch (e) {
	62	+ return -2
	63	+ }
	64	+}
	65	+
	66	+// Case 3: class variable, instanceof an interface
	67	+function testClassToInterface(): int {
	68	+ let b: Base = new Derived(99)
	69	+ try {
	70	+ if (b instanceof IBase) {
	71	+ let i: IBase = b as IBase
	72	+ return i.getVal()
	73	+ }
	74	+ } catch (e) {
	75	+ return -1
	76	+ }
	77	+ return -2
	78	+}
	79	+
	80	+// Case 4: interface variable, instanceof truly unrelated class
	81	+function testInterfaceToUnrelatedClass(): int {
	82	+ let i: IBase = new Derived(5)
	83	+ if (i instanceof Other) {
	84	+ return -1
	85	+ }
	86	+ return i.getVal()
	87	+}
	88	+
	89	+// Case 5: Diamond-like — two interfaces, one class implementing both
	90	+interface IA {
	91	+ a(): int
	92	+}
	93	+interface IB {
	94	+ b(): int
	95	+}
	96	+class Diamond implements IA, IB {
	97	+ a(): int { return 1 }
	98	+ b(): int { return 2 }
	99	+}
	100	+
	101	+function testDiamondInterfaceNarrowing(): int {
	102	+ let x: IA = new Diamond()
	103	+ try {
	104	+ if (x instanceof IB) {
	105	+ let y: IB = x as IB
	106	+ return y.b()
	107	+ }
	108	+ } catch (e) {
	109	+ return -1
	110	+ }
	111	+ return -2
	112	+}
	113	+
	114	+// Case 6: instanceof in else-if chain with interface narrowing
	115	+function testElseIfChain(): int {
	116	+ let x: Object = new Derived(77)
	117	+ if (x instanceof IBase) {
	118	+ let i: IBase = x as IBase
	119	+ return i.getVal()
	120	+ } else if (x instanceof Other) {
	121	+ return -1
	122	+ }
	123	+ return -2
	124	+}
	125	+
	126	+function main(): void {
	127	+ arktest.assertEQ(testInterfaceToClass(), 42)
	128	+ arktest.assertEQ(testInterfaceToInterface(), 10)
	129	+ arktest.assertEQ(testClassToInterface(), 99)
	130	+ arktest.assertEQ(testInterfaceToUnrelatedClass(), 5)
	131	+ arktest.assertEQ(testDiamondInterfaceNarrowing(), 2)
	132	+ arktest.assertEQ(testElseIfChain(), 77)
	133	+}