https://issues.dlang.org/show_bug.cgi?id=18705

          Issue ID: 18705
           Summary: dmd segmentation fault with duplicate class definition
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: test1@wannabephoenix.de

dlang forum: https://forum.dlang.org/post/qlmvefrlyykojtczecib@forum.dlang.org

snippet
https://run.dlang.io/is/OySBGO

the provoking line is commented out in that snippet. when commented in, all compilers give the segfault, including ldc ones. except for 'all dmd compilers..' with version <= 2.066.0

post by LiNbO3 might give more details
> 
> There are a couple of bugs here:
> 
> ---
> void main()
> {
>     { class C { } }
>     class C { }
>     // C x; x.x=1;
>     // static assert (!__traits(compiles, C.x));
> }
> ---
> 
> The first bug can be shown by de-commenting the first line and can be easily solved by modifying hdrgen.d by adding a check on t.sym.parent being non-null to the visit(TypeClass) method.
> Once that's fixed de-comment the second line to have the compiler crash and burn somewhere else.

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