fix issue 7804 - Allow __traits(getMember) as a BasicType

[ghost]

This the continuation of #8031.

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	7804	enhancement	Cannot alias __traits directly

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub fetch digger
dub run digger -- build "master + dmd#8938"

[thewilsonator]

Dscanner dmd/mtype.d(5046:25)[warn]: Useless final attribute, functions declared within a final class are never virtual

[ghost]

I'm afraid that this one has been merged a bit too eagerly so you can still review and will push additional correction if needed. For example i just addressed one of the problem pointed out in the old PR just a few hours ago (statement VS declaration).

[thewilsonator]

Oops sorry.

[ghost]

In theory i think that you should have used the auto-merge label to trigger the bot. Then it wouldn't have worked without the approval of a code owner (reviewers with the locker symbol at the top right corner).

[thewilsonator]

mir-algothithm is currently broken though, is build kite is red. auto-merge wouldn't do anything for a long time.

[Geod24]

Yeah that one definitely needed more review. I for one have comments about the changelog wording and some tests to be added with regards to other traits that the one intended to work.

I understand the desire to be quick but there needs to be a minimal period to allow people to review things, according to the importance of the PR.

[thewilsonator]

Oh for some reason I though the one it was replacing was approved, it wasn't. I've been looking at too many PRs, need to take a break.

[ghost]

@Geod24, can you make suggestions for the changelog entry ?

About the other traits, getMember is checked during parsing. Later what happens during semantic is then that possible getMember errors are not specific to the language enhancement, but are normal traits errors, alias errors or type errors.

I can however add these errors (with the changelog modification PR):

module more;

__traits(getMember, more, "object") not_a_Type; // the trait suceeds but the variable decl not
__traits(getMember, more, "NotExisting") not_existing; // trait error
alias nothing = __traits(getMember, more, "NotExisting"); // trait error          

[Geod24]

Okay, so my first test (with master, 0427b57) was:

class Foo
{
    void func() {}
}

void main ()
{
    __traits(getMember, Foo, "func") var;
}

% ./generated/osx/release/64/dmd foo.d
[3]    81445 segmentation fault  ./generated/osx/release/64/dmd foo.d