K2: for Java source override, don't compare return types in override checker

#KT-57044 Fixed

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosticCompilerTestFirTestdataTestGenerated.java

@@ -6969,6 +6969,18 @@ public class DiagnosticCompilerTestFirTestdataTestGenerated extends AbstractDiag
                 runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/NamedParameterInConcurrentMap.kt");
             }
 
+            @Test
+            @TestMetadata("overriddenFunctionReturningUnit.kt")
+            public void testOverriddenFunctionReturningUnit() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit.kt");
+            }
+
+            @Test
+            @TestMetadata("overriddenFunctionReturningUnit2.kt")
+            public void testOverriddenFunctionReturningUnit2() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit2.kt");
+            }
+
             @Test
             @TestMetadata("qualifierPriority.kt")
             public void testQualifierPriority() throws Exception {

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLFirPreresolvedReversedDiagnosticCompilerFirTestDataTestGenerated.java

@@ -6969,6 +6969,18 @@ public class LLFirPreresolvedReversedDiagnosticCompilerFirTestDataTestGenerated
                 runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/NamedParameterInConcurrentMap.kt");
             }
 
+            @Test
+            @TestMetadata("overriddenFunctionReturningUnit.kt")
+            public void testOverriddenFunctionReturningUnit() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit.kt");
+            }
+
+            @Test
+            @TestMetadata("overriddenFunctionReturningUnit2.kt")
+            public void testOverriddenFunctionReturningUnit2() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit2.kt");
+            }
+
             @Test
             @TestMetadata("qualifierPriority.kt")
             public void testQualifierPriority() throws Exception {

compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit.fir.txt

@@ -0,0 +1,14 @@
+FILE: K.kt
+    public open class K : R|kotlin/Any| {
+        public constructor(): R|K| {
+            super<R|kotlin/Any|>()
+        }
+
+        public open fun test(): R|kotlin/Unit| {
+            ^test Q|kotlin/Unit|
+        }
+
+    }
+    public final fun jk(): R|kotlin/Unit| {
+        R|/JK.JK|().R|/JK.test|()
+    }

compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit.kt

@@ -0,0 +1,18 @@
+// FILE: JK.java
+
+public class JK extends K {
+    @Override
+    public void test() {
+
+    }
+}
+
+// FILE: K.kt
+
+open class K {
+    open fun test() = Unit
+}
+
+fun jk() {
+    JK().test()
+}

compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit2.fir.txt

@@ -0,0 +1,14 @@
+FILE: K.kt
+    public final fun jk(): R|kotlin/Unit| {
+        ^jk R|/JK.JK|().R|/JK.test|()
+    }
+    public open class K : R|kotlin/Any| {
+        public constructor(): R|K| {
+            super<R|kotlin/Any|>()
+        }
+
+        public open fun test(): R|kotlin/Unit| {
+            ^test Q|kotlin/Unit|
+        }
+
+    }

compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit2.kt

@@ -0,0 +1,16 @@
+// FILE: JK.java
+
+public class JK extends K {
+    @Override
+    public void test() {
+
+    }
+}
+
+// FILE: K.kt
+
+fun jk() = JK().test()
+
+open class K {
+    open fun test() = Unit
+}

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirLightTreeDiagnosticsTestGenerated.java

@@ -6969,6 +6969,18 @@ public class FirLightTreeDiagnosticsTestGenerated extends AbstractFirLightTreeDi
                 runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/NamedParameterInConcurrentMap.kt");
             }
 
+            @Test
+            @TestMetadata("overriddenFunctionReturningUnit.kt")
+            public void testOverriddenFunctionReturningUnit() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit.kt");
+            }
+
+            @Test
+            @TestMetadata("overriddenFunctionReturningUnit2.kt")
+            public void testOverriddenFunctionReturningUnit2() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit2.kt");
+            }
+
             @Test
             @TestMetadata("qualifierPriority.kt")
             public void testQualifierPriority() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirPsiDiagnosticTestGenerated.java

@@ -6969,6 +6969,18 @@ public class FirPsiDiagnosticTestGenerated extends AbstractFirPsiDiagnosticTest
                 runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/NamedParameterInConcurrentMap.kt");
             }
 
+            @Test
+            @TestMetadata("overriddenFunctionReturningUnit.kt")
+            public void testOverriddenFunctionReturningUnit() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit.kt");
+            }
+
+            @Test
+            @TestMetadata("overriddenFunctionReturningUnit2.kt")
+            public void testOverriddenFunctionReturningUnit2() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/overriddenFunctionReturningUnit2.kt");
+            }
+
             @Test
             @TestMetadata("qualifierPriority.kt")
             public void testQualifierPriority() throws Exception {

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/scopes/JavaOverrideChecker.kt

@@ -250,7 +250,18 @@ class JavaOverrideChecker internal constructor(
             return false
         }
 
-        if (considerReturnTypeKinds && !doesReturnTypesHaveSameKind(overrideCandidate, baseDeclaration)) return false
+        if (overrideCandidate.origin == FirDeclarationOrigin.Java.Source && baseDeclaration.origin == FirDeclarationOrigin.Source) {
+            // For override from Java source against the Kotlin base the following check of return type kinds is not important
+            // From the other side, it can provoke problems in case baseDeclaration is from source and has an implicit return type
+            // which is not yet resolved (see KT-57044)
+            return true
+        }
+
+        // See test compiler/testData/compileKotlinAgainstCustomBinaries/incorrectJavaSignature
+        // and relevant commit message (360d6741)
+        if (considerReturnTypeKinds && !doesReturnTypesHaveSameKind(overrideCandidate, baseDeclaration)) {
+            return false
+        }
 
         return true
     }