Revert "[FIR] Remove the redundant isFunctionType check"

This reverts commit 1f97c268e1.

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

@@ -5266,12 +5266,6 @@ public class DiagnosticCompilerTestFirTestdataTestGenerated extends AbstractDiag
             runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/backingField.kt");
         }
 
-        @Test
-        @TestMetadata("castForFunctionsWithDifferentArities.kt")
-        public void testCastForFunctionsWithDifferentArities() throws Exception {
-            runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/castForFunctionsWithDifferentArities.kt");
-        }
-
         @Test
         @TestMetadata("classLiteralForParameter.kt")
         public void testClassLiteralForParameter() throws Exception {

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

@@ -5266,12 +5266,6 @@ public class LLFirPreresolvedReversedDiagnosticCompilerFirTestDataTestGenerated
             runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/backingField.kt");
         }
 
-        @Test
-        @TestMetadata("castForFunctionsWithDifferentArities.kt")
-        public void testCastForFunctionsWithDifferentArities() throws Exception {
-            runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/castForFunctionsWithDifferentArities.kt");
-        }
-
         @Test
         @TestMetadata("classLiteralForParameter.kt")
         public void testClassLiteralForParameter() throws Exception {

compiler/fir/analysis-tests/testData/resolveWithStdlib/castForFunctionsWithDifferentArities.fir.txt

@@ -1,12 +0,0 @@
-FILE: castForFunctionsWithDifferentArities.kt
-    public final fun test(b: R|kotlin/Boolean|, block1: R|kotlin/Any.() -> kotlin/Unit|, block2: R|(kotlin/Any.(kotlin/Any?) -> kotlin/Unit)?|): R|kotlin/Unit| {
-        when () {
-            R|<local>/b| ->  {
-                R|kotlin/requireNotNull|<R|kotlin/Any.() -> kotlin/Unit|>(R|<local>/block1|)
-            }
-            else ->  {
-                R|kotlin/requireNotNull|<R|kotlin/Any.(kotlin/Any?) -> kotlin/Unit|>(R|<local>/block2|)
-            }
-        }
-
-    }

compiler/fir/analysis-tests/testData/resolveWithStdlib/castForFunctionsWithDifferentArities.kt

@@ -1,9 +0,0 @@
-// ISSUE: KT-63865
-
-fun test(b: Boolean, block1: Any.() -> Unit, block2: (Any.(Any?) -> Unit)?) {
-    if (b) {
-        requireNotNull(block1)
-    } else {
-        requireNotNull(block2)
-    }
-}

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

@@ -5266,12 +5266,6 @@ public class FirLightTreeDiagnosticsTestGenerated extends AbstractFirLightTreeDi
             runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/backingField.kt");
         }
 
-        @Test
-        @TestMetadata("castForFunctionsWithDifferentArities.kt")
-        public void testCastForFunctionsWithDifferentArities() throws Exception {
-            runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/castForFunctionsWithDifferentArities.kt");
-        }
-
         @Test
         @TestMetadata("classLiteralForParameter.kt")
         public void testClassLiteralForParameter() throws Exception {

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

@@ -5266,12 +5266,6 @@ public class FirPsiDiagnosticTestGenerated extends AbstractFirPsiDiagnosticTest
             runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/backingField.kt");
         }
 
-        @Test
-        @TestMetadata("castForFunctionsWithDifferentArities.kt")
-        public void testCastForFunctionsWithDifferentArities() throws Exception {
-            runTest("compiler/fir/analysis-tests/testData/resolveWithStdlib/castForFunctionsWithDifferentArities.kt");
-        }
-
         @Test
         @TestMetadata("classLiteralForParameter.kt")
         public void testClassLiteralForParameter() throws Exception {

compiler/fir/providers/src/org/jetbrains/kotlin/fir/types/ConeInferenceContext.kt

@@ -69,7 +69,7 @@ interface ConeInferenceContext : TypeSystemInferenceExtensionContext, ConeTypeCo
     ): SimpleTypeMarker {
         val attributesList = attributes?.filterIsInstanceTo<ConeAttribute<*>, MutableList<ConeAttribute<*>>>(mutableListOf())
         val coneAttributes: ConeAttributes = if (isExtensionFunction) {
-            require(constructor is ConeClassLikeLookupTag)
+            require(constructor is ConeClassLikeLookupTag && constructor.isSomeFunctionType(session))
             // We don't want to create new instance of ConeAttributes which
             //   contains only CompilerConeAttributes.ExtensionFunctionType
             //   to avoid memory consumption