Fix CCE in generated code that happens when comparing boxed chars

The problem was that when obtaining char from the wrapper,
codegen used int as expected type that led
to a ClassCastException: java.lang.Character cannot be cast to java.lang.Number

The solution is using coercion to chars, it's still correct,
because of implicit widening coercion in JVM from C to I

 #KT-15105 Fixed

compiler/backend/src/org/jetbrains/kotlin/codegen/AsmUtil.java

@@ -770,6 +770,7 @@ public class AsmUtil {
         if (left == Type.DOUBLE_TYPE || right == Type.DOUBLE_TYPE) return Type.DOUBLE_TYPE;
         if (left == Type.FLOAT_TYPE || right == Type.FLOAT_TYPE) return Type.FLOAT_TYPE;
         if (left == Type.LONG_TYPE || right == Type.LONG_TYPE) return Type.LONG_TYPE;
+        if (left == Type.CHAR_TYPE || right == Type.CHAR_TYPE) return Type.CHAR_TYPE;
         return Type.INT_TYPE;
     }
 

compiler/backend/src/org/jetbrains/kotlin/codegen/intrinsics/CompareTo.kt

@@ -25,7 +25,7 @@ import org.jetbrains.org.objectweb.asm.commons.InstructionAdapter
 class CompareTo : IntrinsicMethod() {
     private fun genInvoke(type: Type?, v: InstructionAdapter) {
         when (type) {
-            Type.INT_TYPE -> v.invokestatic(IntrinsicMethods.INTRINSICS_CLASS_NAME, "compare", "(II)I", false)
+            Type.INT_TYPE, Type.CHAR_TYPE -> v.invokestatic(IntrinsicMethods.INTRINSICS_CLASS_NAME, "compare", "(II)I", false)
             Type.LONG_TYPE -> v.invokestatic(IntrinsicMethods.INTRINSICS_CLASS_NAME, "compare", "(JJ)I", false)
             Type.FLOAT_TYPE -> v.invokestatic("java/lang/Float", "compare", "(FF)I", false)
             Type.DOUBLE_TYPE -> v.invokestatic("java/lang/Double", "compare", "(DD)I", false)

compiler/testData/codegen/box/binaryOp/compareBoxedChars.kt

@@ -0,0 +1,16 @@
+fun <T> id(x: T) = x
+
+fun box(): String {
+    if (id('a') > id('b')) return "fail 1"
+    if (id('a') >= id('b')) return "fail 2"
+    if (id('b') < id('a')) return "fail 3"
+    if (id('b') <= id('a')) return "fail 4"
+
+    val x = id('a').compareTo('b')
+    if (x != -1) return "fail 5"
+
+    val y = id('b').compareTo('a')
+    if (y != 1) return "fail 6"
+
+    return "OK"
+}

compiler/testData/codegen/light-analysis/binaryOp/compareBoxedChars.txt

@@ -0,0 +1,5 @@
+@kotlin.Metadata
+public final class CompareBoxedCharsKt {
+    public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
+    public final static method id(p0: java.lang.Object): java.lang.Object
+}

compiler/tests-ir-jvm/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java

@@ -785,6 +785,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             doTest(fileName);
         }
 
+        @TestMetadata("compareBoxedChars.kt")
+        public void testCompareBoxedChars() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/binaryOp/compareBoxedChars.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("compareWithBoxedDouble.kt")
         public void testCompareWithBoxedDouble() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/binaryOp/compareWithBoxedDouble.kt");

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -785,6 +785,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             doTest(fileName);
         }
 
+        @TestMetadata("compareBoxedChars.kt")
+        public void testCompareBoxedChars() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/binaryOp/compareBoxedChars.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("compareWithBoxedDouble.kt")
         public void testCompareWithBoxedDouble() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/binaryOp/compareWithBoxedDouble.kt");

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java

@@ -977,6 +977,12 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             doTest(fileName);
         }
 
+        @TestMetadata("compareBoxedChars.kt")
+        public void testCompareBoxedChars() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/binaryOp/compareBoxedChars.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("compareWithBoxedDouble.kt")
         public void testCompareWithBoxedDouble() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/binaryOp/compareWithBoxedDouble.kt");