• via Digitalmars-d-bugs (32/32) Nov 02 2016 https://issues.dlang.org/show_bug.cgi?id=16657

via Digitalmars-d-bugs <digitalmars-d-bugs puremagic.com> writes:

https://issues.dlang.org/show_bug.cgi?id=16657

          Issue ID: 16657
           Summary: [The D Bug Tracker]
           Product: D
           Version: D2
          Hardware: All
               URL: http://dlang.org/
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P3
         Component: dmd
          Assignee: nobody puremagic.com
          Reporter: eyal weka.io

When adding an "alias this" to a type, the automatic opEquals and opCmp that
compare the object lexicographically are removed and instead only the alias
this portion of the type is compared via its opEquals/opCmp.

struct A {
    int x;
}

struct B {
    A a, b;
}
static assert(B(A(1), A(1)) != B(A(1), A(2))); // Works

struct C {
    A a, b;
    alias a this;
}
static assert(C(A(1), A(1)) != C(A(1), A(2))); // Fails!

Adding alias this should NOT cause a preference for the base type's
comparators.

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