[Issue 2780] New: ref Return Allows modification of immutable data

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=2780

           Summary: ref Return Allows modification of immutable data
           Product: D
           Version: 2.027
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Keywords: accepts-invalid
          Severity: regression
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla at digitalmars.com
        ReportedBy: dsimcha at yahoo.com


import std.stdio;

struct Immutable {
    immutable uint[2] num;

    ref uint opIndex(uint index) immutable {
        return num[index];
    }
}

void main() {
    immutable Immutable foo;
    writeln(foo[0]);  // Prints 0.
    foo[0]++;
    writeln(foo[0]);  // Prints 1.
}

Probably related to the fix for bug 2728 because the weird error message
provided by 2728 was what used to prevent this bug from happening.


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