Fir2Ir: simplify getCachedIrTypeParameter

I could not figure out the reason for the special case in that function.
Tests do not show anything useful.

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrClassifierStorage.kt

@@ -96,11 +96,11 @@ class Fir2IrClassifierStorage(
     internal fun preCacheTypeParameters(owner: FirTypeParameterRefsOwner, irOwnerSymbol: IrSymbol) {
         for ((index, typeParameter) in owner.typeParameters.withIndex()) {
             val original = typeParameter.symbol.fir
-            getCachedIrTypeParameter(original, index)
+            getCachedIrTypeParameter(original)
                 ?: createIrTypeParameterWithoutBounds(original, index, irOwnerSymbol)
             if (owner is FirProperty && owner.isVar) {
                 val context = ConversionTypeContext.DEFAULT.inSetter()
-                getCachedIrTypeParameter(original, index, context)
+                getCachedIrTypeParameter(original, context)
                     ?: createIrTypeParameterWithoutBounds(original, index, irOwnerSymbol, context)
             }
         }
@@ -429,27 +429,12 @@ class Fir2IrClassifierStorage(
 
     internal fun getCachedIrTypeParameter(
         typeParameter: FirTypeParameter,
-        index: Int = UNDEFINED_PARAMETER_INDEX,
         typeContext: ConversionTypeContext = ConversionTypeContext.DEFAULT
     ): IrTypeParameter? {
-        // Here transformation is a bit difficult because one FIR property type parameter
-        // can be transformed to two different type parameters: one for getter and another one for setter
-        val simpleCachedParameter = typeParameterCache[typeParameter]
-        if (simpleCachedParameter != null) {
-            if (typeContext.origin != ConversionTypeOrigin.SETTER) {
-                return simpleCachedParameter
-            }
-            if (index < 0) {
-                val parent = simpleCachedParameter.parent
-                if (parent !is IrSimpleFunction || parent.returnType == irBuiltIns.unitType) {
-                    return simpleCachedParameter
-                }
-            }
-        }
-        if (typeContext.origin == ConversionTypeOrigin.SETTER) {
-            typeParameterCacheForSetter[typeParameter]?.let { return it }
-        }
-        return null
+        return if (typeContext.origin == ConversionTypeOrigin.SETTER)
+            typeParameterCacheForSetter[typeParameter]
+        else
+            typeParameterCache[typeParameter]
     }
 
     internal fun getIrTypeParameter(
@@ -458,7 +443,7 @@ class Fir2IrClassifierStorage(
         ownerSymbol: IrSymbol,
         typeContext: ConversionTypeContext = ConversionTypeContext.DEFAULT
     ): IrTypeParameter {
-        getCachedIrTypeParameter(typeParameter, index, typeContext)?.let { return it }
+        getCachedIrTypeParameter(typeParameter, typeContext)?.let { return it }
         return typeParameter.run {
             val irTypeParameter = createIrTypeParameterWithoutBounds(typeParameter, index, ownerSymbol, typeContext)
             irTypeParameter.superTypes = bounds.map { it.toIrType() }
@@ -592,7 +577,7 @@ class Fir2IrClassifierStorage(
         typeContext: ConversionTypeContext
     ): IrTypeParameterSymbol {
         val firTypeParameter = firTypeParameterSymbol.fir
-        return getCachedIrTypeParameter(firTypeParameter, typeContext = typeContext)?.symbol
+        return getCachedIrTypeParameter(firTypeParameter, typeContext)?.symbol
         // We can try to use default cache because setter can use parent type parameters
             ?: typeParameterCache[firTypeParameter]?.symbol
             ?: error("Cannot find cached type parameter by FIR symbol: ${firTypeParameterSymbol.name}")

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java

@@ -7181,6 +7181,12 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
             runTest("compiler/testData/codegen/box/compileKotlinAgainstKotlin/fakeOverridesForIntersectionTypes.kt");
         }
 
+        @Test
+        @TestMetadata("genericSetter.kt")
+        public void testGenericSetter() throws Exception {
+            runTest("compiler/testData/codegen/box/compileKotlinAgainstKotlin/genericSetter.kt");
+        }
+
         @Test
         @TestMetadata("importCompanion.kt")
         public void testImportCompanion() throws Exception {

compiler/testData/codegen/box/compileKotlinAgainstKotlin/genericSetter.kt

@@ -0,0 +1,13 @@
+// MODULE: lib
+// FILE: 1.kt
+var <T> T.prop: Int
+    get() = 33
+    set(value) {}
+
+// MODULE: main(lib)
+// FILE: 2.kt
+fun <T> setProp(t: T, v: Int) {
+    t.prop = v
+}
+
+fun box() = "OK"

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxCodegenTestGenerated.java

@@ -7067,6 +7067,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTest("compiler/testData/codegen/box/compileKotlinAgainstKotlin/fakeOverridesForIntersectionTypes.kt");
         }
 
+        @Test
+        @TestMetadata("genericSetter.kt")
+        public void testGenericSetter() throws Exception {
+            runTest("compiler/testData/codegen/box/compileKotlinAgainstKotlin/genericSetter.kt");
+        }
+
         @Test
         @TestMetadata("importCompanion.kt")
         public void testImportCompanion() throws Exception {

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java

@@ -7181,6 +7181,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             runTest("compiler/testData/codegen/box/compileKotlinAgainstKotlin/fakeOverridesForIntersectionTypes.kt");
         }
 
+        @Test
+        @TestMetadata("genericSetter.kt")
+        public void testGenericSetter() throws Exception {
+            runTest("compiler/testData/codegen/box/compileKotlinAgainstKotlin/genericSetter.kt");
+        }
+
         @Test
         @TestMetadata("importCompanion.kt")
         public void testImportCompanion() throws Exception {

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/JvmIrAgainstOldBoxTestGenerated.java

@@ -163,6 +163,12 @@ public class JvmIrAgainstOldBoxTestGenerated extends AbstractJvmIrAgainstOldBoxT
         runTest("compiler/testData/codegen/box/compileKotlinAgainstKotlin/fakeOverridesForIntersectionTypes.kt");
     }
 
+    @Test
+    @TestMetadata("genericSetter.kt")
+    public void testGenericSetter() throws Exception {
+        runTest("compiler/testData/codegen/box/compileKotlinAgainstKotlin/genericSetter.kt");
+    }
+
     @Test
     @TestMetadata("importCompanion.kt")
     public void testImportCompanion() throws Exception {

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/JvmOldAgainstIrBoxTestGenerated.java

@@ -163,6 +163,12 @@ public class JvmOldAgainstIrBoxTestGenerated extends AbstractJvmOldAgainstIrBoxT
         runTest("compiler/testData/codegen/box/compileKotlinAgainstKotlin/fakeOverridesForIntersectionTypes.kt");
     }
 
+    @Test
+    @TestMetadata("genericSetter.kt")
+    public void testGenericSetter() throws Exception {
+        runTest("compiler/testData/codegen/box/compileKotlinAgainstKotlin/genericSetter.kt");
+    }
+
     @Test
     @TestMetadata("importCompanion.kt")
     public void testImportCompanion() throws Exception {

native/native.tests/tests-gen/org/jetbrains/kotlin/konan/blackboxtest/NativeCodegenBoxTestGenerated.java

@@ -5515,6 +5515,12 @@ public class NativeCodegenBoxTestGenerated extends AbstractNativeCodegenBoxTest
                 runTest("compiler/testData/codegen/box/compileKotlinAgainstKotlin/expectClassActualTypeAlias.kt");
             }
 
+            @Test
+            @TestMetadata("genericSetter.kt")
+            public void testGenericSetter() throws Exception {
+                runTest("compiler/testData/codegen/box/compileKotlinAgainstKotlin/genericSetter.kt");
+            }
+
             @Test
             @TestMetadata("innerClassConstructor.kt")
             public void testInnerClassConstructor() throws Exception {