[FIR] Fix generic sam conversion in call completion

#KT-60903 Fixed

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirCallCompletionResultsWriterTransformer.kt

@@ -560,20 +560,7 @@ class FirCallCompletionResultsWriterTransformer(
                 // a built-in functional type, no-brainer
                 expectedArgumentType.isSomeFunctionType(session) -> expectedArgumentType
                 // fun interface (a.k.a. SAM), then unwrap it and build a functional type from that interface function
-                expectedArgumentType is ConeClassLikeType -> {
-                    expectedArgumentType.lookupTag.toFirRegularClass(session)?.let answer@{ firRegularClass ->
-                        val functionType = samResolver.getFunctionTypeForPossibleSamType(firRegularClass.defaultType())
-                            ?: return@answer null
-                        val kind = functionType.functionTypeKind(session) ?: FunctionTypeKind.Function
-                        createFunctionType(
-                            kind,
-                            functionType.typeArguments.dropLast(1).map { it as ConeKotlinType },
-                            null,
-                            functionType.typeArguments.last() as ConeKotlinType
-                        )
-                    }
-                }
-                else -> null
+                else -> samResolver.getFunctionTypeForPossibleSamType(expectedArgumentType)?.lowerBoundIfFlexible()
             }
         }
 

compiler/incremental-compilation-impl/test/org/jetbrains/kotlin/incremental/IncrementalFirICLightTreeJvmCompilerRunnerTestGenerated.java

@@ -577,6 +577,11 @@ public class IncrementalFirICLightTreeJvmCompilerRunnerTestGenerated extends Abs
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/returnTypeChanged/");
         }
 
+        @TestMetadata("samConversion")
+        public void testSamConversion() throws Exception {
+            runTest("jps/jps-plugin/testData/incremental/pureKotlin/samConversion/");
+        }
+
         @TestMetadata("sealedClassesAddImplements")
         public void testSealedClassesAddImplements() throws Exception {
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/sealedClassesAddImplements/");

compiler/incremental-compilation-impl/test/org/jetbrains/kotlin/incremental/IncrementalFirLightTreeJvmCompilerRunnerTestGenerated.java

@@ -577,6 +577,11 @@ public class IncrementalFirLightTreeJvmCompilerRunnerTestGenerated extends Abstr
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/returnTypeChanged/");
         }
 
+        @TestMetadata("samConversion")
+        public void testSamConversion() throws Exception {
+            runTest("jps/jps-plugin/testData/incremental/pureKotlin/samConversion/");
+        }
+
         @TestMetadata("sealedClassesAddImplements")
         public void testSealedClassesAddImplements() throws Exception {
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/sealedClassesAddImplements/");

compiler/incremental-compilation-impl/test/org/jetbrains/kotlin/incremental/IncrementalK1JsKlibCompilerRunnerTestGenerated.java

@@ -591,6 +591,11 @@ public class IncrementalK1JsKlibCompilerRunnerTestGenerated extends AbstractIncr
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/returnTypeChanged/");
         }
 
+        @TestMetadata("samConversion")
+        public void testSamConversion() throws Exception {
+            runTest("jps/jps-plugin/testData/incremental/pureKotlin/samConversion/");
+        }
+
         @TestMetadata("secondaryConstructorInlined")
         public void testSecondaryConstructorInlined() throws Exception {
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/secondaryConstructorInlined/");

compiler/incremental-compilation-impl/test/org/jetbrains/kotlin/incremental/IncrementalK1JsKlibCompilerWithScopeExpansionRunnerTestGenerated.java

@@ -591,6 +591,11 @@ public class IncrementalK1JsKlibCompilerWithScopeExpansionRunnerTestGenerated ex
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/returnTypeChanged/");
         }
 
+        @TestMetadata("samConversion")
+        public void testSamConversion() throws Exception {
+            runTest("jps/jps-plugin/testData/incremental/pureKotlin/samConversion/");
+        }
+
         @TestMetadata("secondaryConstructorInlined")
         public void testSecondaryConstructorInlined() throws Exception {
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/secondaryConstructorInlined/");

compiler/incremental-compilation-impl/test/org/jetbrains/kotlin/incremental/IncrementalK1JvmCompilerRunnerTestGenerated.java

@@ -592,6 +592,11 @@ public class IncrementalK1JvmCompilerRunnerTestGenerated extends AbstractIncreme
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/returnTypeChanged/");
         }
 
+        @TestMetadata("samConversion")
+        public void testSamConversion() throws Exception {
+            runTest("jps/jps-plugin/testData/incremental/pureKotlin/samConversion/");
+        }
+
         @TestMetadata("sealedClassesAddImplements")
         public void testSealedClassesAddImplements() throws Exception {
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/sealedClassesAddImplements/");

compiler/incremental-compilation-impl/test/org/jetbrains/kotlin/incremental/IncrementalK2JsKlibCompilerWithScopeExpansionRunnerTestGenerated.java

@@ -586,6 +586,11 @@ public class IncrementalK2JsKlibCompilerWithScopeExpansionRunnerTestGenerated ex
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/returnTypeChanged/");
         }
 
+        @TestMetadata("samConversion")
+        public void testSamConversion() throws Exception {
+            runTest("jps/jps-plugin/testData/incremental/pureKotlin/samConversion/");
+        }
+
         @TestMetadata("secondaryConstructorInlined")
         public void testSecondaryConstructorInlined() throws Exception {
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/secondaryConstructorInlined/");

compiler/incremental-compilation-impl/test/org/jetbrains/kotlin/incremental/IncrementalK2JvmCompilerRunnerTestGenerated.java

@@ -577,6 +577,11 @@ public class IncrementalK2JvmCompilerRunnerTestGenerated extends AbstractIncreme
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/returnTypeChanged/");
         }
 
+        @TestMetadata("samConversion")
+        public void testSamConversion() throws Exception {
+            runTest("jps/jps-plugin/testData/incremental/pureKotlin/samConversion/");
+        }
+
         @TestMetadata("sealedClassesAddImplements")
         public void testSealedClassesAddImplements() throws Exception {
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/sealedClassesAddImplements/");

jps/jps-plugin/jps-tests/test/org/jetbrains/kotlin/jps/build/IncrementalK1JvmJpsTestGenerated.java

@@ -1261,6 +1261,11 @@ public class IncrementalK1JvmJpsTestGenerated extends AbstractIncrementalK1JvmJp
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/returnTypeChanged/");
         }
 
+        @TestMetadata("samConversion")
+        public void testSamConversion() throws Exception {
+            runTest("jps/jps-plugin/testData/incremental/pureKotlin/samConversion/");
+        }
+
         @TestMetadata("sealedClassesAddImplements")
         public void testSealedClassesAddImplements() throws Exception {
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/sealedClassesAddImplements/");

jps/jps-plugin/jps-tests/test/org/jetbrains/kotlin/jps/build/IncrementalK2FirICLightTreeJvmJpsTestGenerated.java

@@ -587,6 +587,11 @@ public class IncrementalK2FirICLightTreeJvmJpsTestGenerated extends AbstractIncr
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/returnTypeChanged/");
         }
 
+        @TestMetadata("samConversion")
+        public void testSamConversion() throws Exception {
+            runTest("jps/jps-plugin/testData/incremental/pureKotlin/samConversion/");
+        }
+
         @TestMetadata("sealedClassesAddImplements")
         public void testSealedClassesAddImplements() throws Exception {
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/sealedClassesAddImplements/");

jps/jps-plugin/jps-tests/test/org/jetbrains/kotlin/jps/build/IncrementalK2JvmJpsTestGenerated.java

@@ -587,6 +587,11 @@ public class IncrementalK2JvmJpsTestGenerated extends AbstractIncrementalK2JvmJp
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/returnTypeChanged/");
         }
 
+        @TestMetadata("samConversion")
+        public void testSamConversion() throws Exception {
+            runTest("jps/jps-plugin/testData/incremental/pureKotlin/samConversion/");
+        }
+
         @TestMetadata("sealedClassesAddImplements")
         public void testSealedClassesAddImplements() throws Exception {
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/sealedClassesAddImplements/");

jps/jps-plugin/jps-tests/test/org/jetbrains/kotlin/jps/build/IncrementalK2LightTreeJvmJpsTestGenerated.java

@@ -587,6 +587,11 @@ public class IncrementalK2LightTreeJvmJpsTestGenerated extends AbstractIncrement
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/returnTypeChanged/");
         }
 
+        @TestMetadata("samConversion")
+        public void testSamConversion() throws Exception {
+            runTest("jps/jps-plugin/testData/incremental/pureKotlin/samConversion/");
+        }
+
         @TestMetadata("sealedClassesAddImplements")
         public void testSealedClassesAddImplements() throws Exception {
             runTest("jps/jps-plugin/testData/incremental/pureKotlin/sealedClassesAddImplements/");

jps/jps-plugin/testData/incremental/pureKotlin/samConversion/build.log

@@ -0,0 +1,13 @@
+================ Step #1 =================
+
+Cleaning output files:
+  out/production/module/META-INF/module.kotlin_module
+  out/production/module/MainKt$main$1$1$1.class
+  out/production/module/MainKt$main$2.class
+  out/production/module/MainKt.class
+End of files
+Compiling files:
+  src/main.kt
+End of files
+Exit code: OK
+------------------------------------------

jps/jps-plugin/testData/incremental/pureKotlin/samConversion/main.kt

@@ -0,0 +1,17 @@
+fun main() {
+    Observable.of(1, 2)
+        .apply({ observable ->
+            Observable { subscriber ->
+                (observable).subscribe(object : Observer<Int> {
+                    override fun next(value: Int) {
+                        subscriber.next(value * 2)
+                    }
+
+                })
+            }
+        })
+        .subscribe(object : Subscriber<Int>() {
+            override fun next(value: Int) {
+            }
+        })
+}

jps/jps-plugin/testData/incremental/pureKotlin/samConversion/observable.kt

@@ -0,0 +1,33 @@
+open class Subscription
+
+interface Observer<T> {
+    fun next(value: T)
+}
+
+open class Subscriber<T>(observer: Observer<T>? = null) : Subscription(), Observer<T> {
+    override fun next(value: T) {}
+}
+
+fun interface Subscribe<T> {
+    fun subscribe(subscriber: Subscriber<T>): Subscription
+}
+
+fun interface Operator<X, Y> {
+    fun call(source: Observable<X>): Observable<Y>
+}
+
+open class Observable<T>(private val subscribeFn: Subscribe<T>) {
+    fun <R> apply(operator: Operator<T, R>): Observable<R> {
+        return operator.call(this)
+    }
+
+    fun subscribe(observer: Observer<T>): Subscription {
+        return Subscription()
+    }
+
+    companion object {
+        fun <T> of(vararg elems: T): Observable<T> {
+            return Observable { Subscription() }
+        }
+    }
+}