`_` is not considered a keyword

CFR version

0.149-SNAPSHOT (commit da9725ba)

Compiler

javac 11.0.5

Description

_ (underscore) is not considered a keyword even though it is one since Java 9 (JLS 3.9).

Renaming types, methods or fields should probably only be done when explicitly enabled. However local variable names (when compiled with -g:vars) should possibly always be renamed. Or both should be done based on the class file version?

Here (remove suffix .txt) is a class file which claims to be Java 11 (major 55, minor 0) but uses _ for a field and a local variable. Neither of them are renamed regardless of the --renameillegalidents value.

[leibnitz27]

Oh that’s hilarious, I never pushed that. Whoops. Pushed now. Basically, acts as a easier way to override all the class file dependent options. (but will of course produce weird output if you try to be silly, like switch expressions in constructors, or take j10 string concatenation back to j6).

(and if you try to force v1 on a new class file, table sizes have changed, so BANG)

java org.benf.cfr.reader.Main SwitchTest30.class

/*
 * Decompiled with CFR <Could not determine version>.
 */
package org.benf.cfr.tests;

public class SwitchTest30 {
    public static void foo(String x) {
        System.out.println(switch (x) {
            case "Jennifer" -> throw new IllegalStateException();
            case "Alison", "Phillipa" -> {
                System.out.println("JIM");
                yield "JIM";
            }
            case "Sue", "Deborah", "Annabel" -> "FRED";
            default -> {
                if (x.length() > 4) {
                    yield "ALICE";
                }
                System.out.println("BOB!");
                yield "BOB";
            }
        });
    }

    public static void main(String ... args) {
        SwitchTest30.foo("Jennifer");
        SwitchTest30.foo("Sue");
        SwitchTest30.foo("Debbie");
    }
}

vs

java org.benf.cfr.reader.Main SwitchTest30.class --forceclassfilever j6

/*
 * Decompiled with CFR <Could not determine version>.
 */
package org.benf.cfr.tests;

public class SwitchTest30 {
    public static void foo(String x) {
        String string;
        String string2 = x;
        int n = -1;
        switch (string2.hashCode()) {
            case -1478439579: {
                if (!string2.equals("Jennifer")) break;
                n = 0;
                break;
            }
            case 1963877204: {
                if (!string2.equals("Alison")) break;
                n = 1;
                break;
            }
            case -1388868631: {
                if (!string2.equals("Phillipa")) break;
                n = 2;
                break;
            }
            case 83491: {
                if (!string2.equals("Sue")) break;
                n = 3;
                break;
            }
            case -1088790357: {
                if (!string2.equals("Deborah")) break;
                n = 4;
                break;
            }
            case 811978185: {
                if (!string2.equals("Annabel")) break;
                n = 5;
            }
        }
        switch (n) {
            case 0: {
                throw new IllegalStateException();
            }
            case 1:
            case 2: {
                System.out.println("JIM");
                string = "JIM";
                break;
            }
            case 3:
            case 4:
            case 5: {
                string = "FRED";
                break;
            }
            default: {
                if (x.length() > 4) {
                    string = "ALICE";
                    break;
                }
                System.out.println("BOB!");
                string = "BOB";
            }
        }
        System.out.println(string);
    }

    public static void main(String ... args) {
        SwitchTest30.foo("Jennifer");
        SwitchTest30.foo("Sue");
        SwitchTest30.foo("Debbie");
    }

[Marcono1234]

unless a override version is set explicitly

Is that an option / feature already (sorry if I overlooked that) or are you planning to add that?