FirCallCompleter: unwrap definitely not-null type properly

#KT-50180 Fixed

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

@@ -5555,6 +5555,12 @@ public class DiagnosisCompilerFirTestdataTestGenerated extends AbstractDiagnosis
                 runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/DeepCopyIrTree.kt");
             }
 
+            @Test
+            @TestMetadata("definitelyNotNullCast.kt")
+            public void testDefinitelyNotNullCast() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/definitelyNotNullCast.kt");
+            }
+
             @Test
             @TestMetadata("EnumMapGet.kt")
             public void testEnumMapGet() throws Exception {

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

@@ -0,0 +1,14 @@
+FILE: test.kt
+    public open class Value : R|kotlin/Any| {
+        public constructor(s: R|kotlin/String|): R|Value| {
+            super<R|kotlin/Any|>()
+        }
+
+        public final val s: R|kotlin/String| = R|<local>/s|
+            public get(): R|kotlin/String|
+
+    }
+    public final val generator: R|Generator| = R|/Generator.Generator|()
+        public get(): R|Generator|
+    public final val y: R|Value| = (R|/generator|.R|/Generator.createValue|<R|ft<Value, Value?>|>(String(Omega)) as R|Value|)
+        public get(): R|Value|

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

@@ -0,0 +1,17 @@
+// FILE: Generator.java
+
+import org.jetbrains.annotations.NotNull;
+
+public class Generator {
+    @NotNull
+    public <T extends Value> T createValue(@NotNull String content) {
+        return (T) (new Value(content));
+    }
+}
+
+// FILE: test.kt
+open class Value(val s: String)
+
+val generator = Generator()
+
+val y = generator.createValue("Omega") <!USELESS_CAST!>as Value<!>

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

@@ -5555,6 +5555,12 @@ public class FirDiagnosticTestGenerated extends AbstractFirDiagnosticTest {
                 runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/DeepCopyIrTree.kt");
             }
 
+            @Test
+            @TestMetadata("definitelyNotNullCast.kt")
+            public void testDefinitelyNotNullCast() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/definitelyNotNullCast.kt");
+            }
+
             @Test
             @TestMetadata("EnumMapGet.kt")
             public void testEnumMapGet() throws Exception {

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

@@ -5555,6 +5555,12 @@ public class FirDiagnosticsWithLightTreeTestGenerated extends AbstractFirDiagnos
                 runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/DeepCopyIrTree.kt");
             }
 
+            @Test
+            @TestMetadata("definitelyNotNullCast.kt")
+            public void testDefinitelyNotNullCast() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/definitelyNotNullCast.kt");
+            }
+
             @Test
             @TestMetadata("EnumMapGet.kt")
             public void testEnumMapGet() throws Exception {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/FirCallCompleter.kt

@@ -345,14 +345,18 @@ internal fun FirFunction.isFunctionForExpectTypeFromCastFeature(): Boolean {
 
     val returnType = returnTypeRef.coneTypeSafe<ConeKotlinType>() ?: return false
 
-    if ((returnType.lowerBoundIfFlexible() as? ConeTypeParameterType)?.lookupTag != typeParameter.symbol.toLookupTag()) return false
+    if ((returnType.unwrap() as? ConeTypeParameterType)?.lookupTag != typeParameter.symbol.toLookupTag()) return false
 
     fun FirTypeRef.isBadType() =
         coneTypeSafe<ConeKotlinType>()
-            ?.contains { (it.lowerBoundIfFlexible() as? ConeTypeParameterType)?.lookupTag == typeParameter.symbol.toLookupTag() } != false
+            ?.contains { (it.unwrap() as? ConeTypeParameterType)?.lookupTag == typeParameter.symbol.toLookupTag() } != false
 
     if (valueParameters.any { it.returnTypeRef.isBadType() } || receiverTypeRef?.isBadType() == true) return false
 
     return true
 }
 
+private fun ConeKotlinType.unwrap(): ConeSimpleKotlinType = lowerBoundIfFlexible().let {
+    if (it is ConeDefinitelyNotNullType) it.original.unwrap() else it
+}
+