Restore original variable name mangling for captured/receiver $this

Design for the new one is still not finished.

compiler/backend/src/org/jetbrains/kotlin/codegen/VariableAsmNameManglingUtils.kt

@@ -37,22 +37,14 @@ fun mangleNameIfNeeded(name: String): String {
             if (c.isValidCharacter()) {
                 append(c)
             } else {
-                append('-').append(c.toHex())
+                val hexString = Integer.toHexString(c.toInt())
+                assert(hexString.length <= 4)
+                append("_u").append(hexString)
             }
         }
     }
 }
 
-private fun Char.toHex(): String {
-    val hexString = Integer.toHexString(this.toInt())
-    assert(hexString.length <= 4)
-    return if (hexString.length == 4) {
-        hexString
-    } else {
-        "0".repeat(4 - hexString.length) + hexString
-    }
-}
-
 private fun Char.isValidCharacter(): Boolean {
     return this != '$' && this != '-' && isValidDalvikCharacter(this)
 }

compiler/testData/checkLocalVariablesTable/destructuringInSuspendLambda/underscoreNames.kt

@@ -13,6 +13,6 @@ suspend fun test() = foo(A()) { (x_param, _, y_param) -> x_param + y_param }
 // METHOD : UnderscoreNamesKt$test$2.invokeSuspend(Ljava/lang/Object;)Ljava/lang/Object;
 // VARIABLE : NAME=this TYPE=LUnderscoreNamesKt$test$2; INDEX=0
 // VARIABLE : NAME=result TYPE=Ljava/lang/Object; INDEX=1
-// VARIABLE : NAME=$dstr$x_param$-0024_-0024$y_param TYPE=LA; INDEX=2
+// VARIABLE : NAME=$dstr$x_param$_u24__u24$y_param TYPE=LA; INDEX=2
 // VARIABLE : NAME=x_param TYPE=Ljava/lang/String; INDEX=3
 // VARIABLE : NAME=y_param TYPE=Ljava/lang/String; INDEX=4

compiler/testData/checkLocalVariablesTable/underscoreNames.kt

@@ -28,7 +28,7 @@ fun box() {
 // VARIABLE : NAME=c TYPE=C INDEX=9
 // VARIABLE : NAME=a TYPE=D INDEX=7
 // VARIABLE : NAME=this TYPE=LUnderscoreNamesKt$box$1; INDEX=0
-// VARIABLE : NAME=$dstr$x$-0024_-0024$y TYPE=LA; INDEX=1
+// VARIABLE : NAME=$dstr$x$_u24__u24$y TYPE=LA; INDEX=1
 // VARIABLE : NAME=$noName_1 TYPE=Ljava/lang/String; INDEX=2
 // VARIABLE : NAME=w TYPE=I INDEX=3
 // VARIABLE : NAME=x TYPE=D INDEX=4

compiler/testData/codegen/asmLike/receiverMangling/localFunctions.txt

@@ -77,8 +77,8 @@ final class LocalFunctionsKt$foo$5 : kotlin/jvm/internal/Lambda, kotlin/jvm/func
 public final class LocalFunctionsKt : java/lang/Object {
     public final static void foo() {
         Local variables:
-            4 $fun$c-0024d$5: LLocalFunctionsKt$foo$5;
-            3 $fun$b-0020c$4: LLocalFunctionsKt$foo$4;
+            4 $fun$c_u24d$5: LLocalFunctionsKt$foo$5;
+            3 $fun$b_u20c$4: LLocalFunctionsKt$foo$4;
             2 $fun$a2$3: LLocalFunctionsKt$foo$3;
             1 $fun$a2$2: LLocalFunctionsKt$foo$2;
             0 $fun$a$1: LLocalFunctionsKt$foo$1;

compiler/testData/codegen/asmLike/receiverMangling/mangledNames.txt

@@ -101,10 +101,10 @@ final class MangledNamesKt$foo$1 : kotlin/jvm/internal/Lambda, kotlin/jvm/functi
 
     public java.lang.Object invoke(java.lang.Object p0)
 
-    public final void invoke(Arr $dstr$a-0020b$b-0024c$c-002dd$b-0024-0024c-002d-002dd$a-0028-0029§-0026-002a-0026-005e-0040あ化) {
+    public final void invoke(Arr $dstr$a_u20b$b_u24c$c_u2dd$b_u24_u24c_u2d_u2dd$a_u28_u29§_u26_u2a_u26_u5e_u40あ化) {
         Local variables:
             0 this: LMangledNamesKt$foo$1;
-            1 $dstr$a-0020b$b-0024c$c-002dd$b-0024-0024c-002d-002dd$a-0028-0029§-0026-002a-0026-005e-0040あ化: LArr;
+            1 $dstr$a_u20b$b_u24c$c_u2dd$b_u24_u24c_u2d_u2dd$a_u28_u29§_u26_u2a_u26_u5e_u40あ化: LArr;
             2 a b: I
             3 b$c: I
             4 c-d: I

idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/lambdas/underscoreNames.out

@@ -8,7 +8,7 @@ Compile bytecode for arrayOfA
  frame    = invoke:18, UnderscoreNamesKt$main$1 {underscoreNames}
    this     = this = {underscoreNames.UnderscoreNamesKt$main$1@uniqueID}Function3<underscoreNames.A, java.lang.String, java.lang.Integer, java.lang.String>
      field    = arity: int = 3 (sp = Lambda.!EXT!)
-   local    = $dstr$x$-0024_-0024$y: underscoreNames.A = {underscoreNames.A@uniqueID}A(x=1.0, y=, z=0) (sp = null)
+   local    = $dstr$x$_u24__u24$y: underscoreNames.A = {underscoreNames.A@uniqueID}A(x=1.0, y=, z=0) (sp = null)
      field    = x: double = 1.0 (sp = underscoreNames.kt, 2)
      field    = y: java.lang.String =  (sp = underscoreNames.kt, 2)
        field    = value: char[] = {char[0]@uniqueID} (sp = String.!EXT!)