Java text block parser mangles a char on escaped eol

[som-snytt]

Reproduction steps

Scala version: 2.13.8

    final static String simpleString = """
X\
Y
""";

Problem

The test sees

00000360  0a 22 22 22 3b 0a 0a 3d  3d 3d 3d 0a 00 59 0a 0a  |.""";..====..Y..|
00000370  3d 3d 3d 3d 0a 0a 3d 3d  3d 3d 0a                 |====..====.|

or

====
^@Y

====

instead of expected XY. The existing test drops a space char that is hard to spot. (Edit: now I count 8 spaces. Space blindness?)

[som-snytt]

Visible in -Vprint:parser

 <static> val s: String("\u0000Y\n") = _;

[SethTisue]

Which test, where is the test?

Does this affect anything other than the -Vprint:parser output?

The only scenario Dale or I can think of offhand where it might be user-visible is constant folding? Do we constant-fold from Java sources?

cc @harpocrates

[som-snytt]

Noticed during scala/scala3#14882 port of #12290

https://github.com/harpocrates/scala/blob/a8225a093da82381cc4bd7634492c237a3defcc9/test/files/run/t12290/TextBlocks.java

[som-snytt]

Following up, dotty had a related bug, and I see I did not answer the question about visibility.

➜  i18490 cat Z.java

public class Z {

  public static final char X = '\52';  // 42 decimal or '*'

}
➜  i18490 cat Y.scala

class Y {
  final val y = Z.X + 1
}
➜  i18490 scalac Y.scala Z.java
➜  i18490 scala
Welcome to Scala 2.13.11 (OpenJDK 64-Bit Server VM, Java 20.0.1).
Type in expressions for evaluation. Or try :help.

scala> new Y().y
val res0: Int = 43

scala> new Y().y.toChar
val res1: Char = +

scala> Z.X   // no Z.class
       ^
       error: not found: value Z

scala> '\52'  // today I needed quickfix in REPL
        ^
       error: octal escape literals are unsupported: use \u002a instead

scala> '\u002a'
val res3: Char = *

scala> '\u002a'.toInt
val res4: Int = 42

also javap

  public final int y();
    descriptor: ()I
    flags: (0x0011) ACC_PUBLIC, ACC_FINAL
    Code:
      stack=1, locals=1, args_size=1
         0: bipush        43
         2: ireturn