[Issue 20653] New: Short-circuiting boolean logic not working

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20653

          Issue ID: 20653
           Summary: Short-circuiting boolean logic not working
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: turkeyman at gmail.com

I feel like this should work:

enum Thing { A, B }
enum IsThing(T) = is(T == enum) || (__traits(getLinkage, T) == "C++");
enum Is = IsThing!Thing;

> Error: argument to `__traits(getLinkage, Thing)` is not a declaration
> Error: template instance `IsThing!(Thing)` error instantiating

`is(T == enum)` is true, so it shouldn't attempt to evaluate `getLinkage`.

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