• via Digitalmars-d-bugs (37/37) Sep 15 2016 https://issues.dlang.org/show_bug.cgi?id=16496

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

https://issues.dlang.org/show_bug.cgi?id=16496

          Issue ID: 16496
           Summary: __traits(getAttributes, ...) should work with built-in
                    types
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody puremagic.com
          Reporter: issues.dlang jmdavisProg.com

Currently, __traits(getAttributes, ...) does not work with types such as int.
Now, no code is going to need to do something like __traits(getAttributes,
int), because it's guaranteed that int isn't going to have any UDAs - no
built-in type will. However, where it can become a problem is generic code,
code that is dealing with types generically and involves checking for UDAs will
have explicitly check for built-in types rather than feeding them to
__traits(getAttributes, ...) like every other type. So, from a usability
perspective and in the interest of types being treated consistently,
__traits(getAttributes, ...) really should accept built-in types even if the
result is always going to be empty.

Now, the reason that this proble exists is because - contrary to the
expectations of most programmers - the language does not consider built-in
types to be symbols, just keywords. It's the same reason why issue# 9029
exists. As I undarstand it, Walter has agreed to fix it so that alias
parameters accept built-in types. Depending on how that is implemented, that
may or may not automatically fix this. If the solution is to treat all built-in
types as symbols in addition to keywords (which is what most folks would
expect), then this issue will be fixed as well, but if the solution is to
special-case alias template parameters so that they work with built-in types in
addition to symbols, then this issue will remain unaffected.

This issue came up recently in D.Learn:
http://forum.dlang.org/post/nrdn96$2bt$1 digitalmars.com

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