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  1. JDK
  2. JDK-8236682

Javac generates a redundant FieldRef constant for record fields

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Details

    • Bug
    • Resolution: Fixed
    • P3
    • 15
    • 14
    • tools
    • b06

    Description

      Given the following record:

          public record Range(int lo, int hi) {}

      Javac generates 2 FieldRef constants for either field. javap -c Range.class:

      public final class Range extends java.lang.Record {
        public Range(int, int);
          Code:
             0: aload_0
             1: invokespecial #1 // Method java/lang/Record."<init>":()V
             4: aload_0
             5: iload_1
             6: putfield #7 // Field lo:I
             9: aload_0
            10: iload_2
            11: putfield #13 // Field hi:I
            14: return
        ...

        public int lo();
          Code:
             0: aload_0
             1: getfield #16 // Field lo:I
             4: ireturn

        public int hi();
          Code:
             0: aload_0
             1: getfield #17 // Field hi:I
             4: ireturn
      }

      Note that the constructor and accessors use different FieldRef constants (#7 -> #16, #13 -> #17), while for a regular class these would be the same FieldRef constant. The extra FieldRef constant in the case of the record seems to be redundant.

      This issue was found by Nicolai Parlog during his live stream exploring records: https://clips.twitch.tv/PoorCrispyClintmullinsTBCheesePull

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            vromero Vicente Arturo Romero Zaldivar
            jvernee Jorn Vernee
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              Created:
              Updated:
              Resolved: