[Issue 19786] alias to __traits(getMember) wrongfully always binds to this

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19786

--- Comment #6 from Basile-z <b2.temp at gmx.com> ---
I have an excellent news. Si I was rewriting TypeTraits semantic, decomposing
all possible Expressions kinds wit the idea to filter out the invalid cases and
then realized that TypeTraits semantic is not the issue **at all**. 

IN the original report, if you use the old way, i.e `AliasSeq`, then the same
problem occurs, see https://run.dlang.io/is/PGzqGp.

The bug more likely lies in __traits semantic.

Sorry if my comment lead you in the wrong direction and good luck with the fix.

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