throws clauses are simplified

CFR version

0.149-SNAPSHOT (commit 254c677)

Compiler

javac 11.0.5

Description

throws clauses are simplified, duplicate declared exceptions are omitted and generic types are reduced to their erasure type. While this results in functionally equivalent code, the difference can be detected using reflection.

Source:

class ThrowsClauseExact<E extends Exception> {
    public void testThrow() throws Exception, E, E, RuntimeException, RuntimeException { }
    
    public static void main(String... args) throws Exception {
        System.out.println(ThrowsClauseExact.class.getMethod("testThrow").getExceptionTypes().length);
    }
}

Decompiled output:

class ThrowsClauseExact<E extends Exception> {
    ThrowsClauseExact() {
    }

    public void testThrow() throws RuntimeException, Exception {
    }

    public static void main(String ... arrstring) throws Exception {
        System.out.println(ThrowsClauseExact.class.getMethod("testThrow", new Class[0]).getExceptionTypes().length);
    }
}

[leibnitz27]

Lol. I had to.

ThrowsClauseExact2.class.txt

@ItzSomebody - Chris, you might find that one amusing in fernflower.

[leibnitz27]

Did you try decompiling the above in idea/fernflower? 😃 Not so much a side effect in the class file, rather one left for the unwary reader, or the immediate recompiler - It’s a bit silly, but it’s a fun trap to leave…

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//

package org.benf.cfr.tests;

class ThrowsClauseExact2<EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE extends Exception> {
    ThrowsClauseExact2() {
    }

    public void testThrow() throws Exception { System.out.println("They found me.  I don't know how, but they found me..");} {
    }

    public static void main(String... args) throws Exception {
        (new ThrowsClauseExact2()).testThrow();
    }
}