http://d.puremagic.com/issues/show_bug.cgi?id=11012

           Summary: [TDPL] is(typeof(f) == function) fails with some
                    functions
           Product: D
           Version: unspecified
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: andrei@erdani.com


--- Comment #0 from Andrei Alexandrescu <andrei@erdani.com> 2013-09-11 12:34:19 PDT ---
Consider TDPL example om page 150:

auto f = (int i) {};
assert(is(f == function));

That example has a typo, should be:

auto f = (int i) {};
assert(is(typeof(f) == function));

That still doesn't work, which brings us to this bug. The type of the function is deduced as

void function(int i) pure nothrow @safe

and that fails the "is" test when compared against the bare "function" keyword. As "function" by itself does not represent a type, the test should pass for all functions, however qualified.

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http://d.puremagic.com/issues/show_bug.cgi?id=11012


Maxim Fomin <maxim@maxim-fomin.ru> changed:

           What    |Removed                     |Added
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                 CC|                            |maxim@maxim-fomin.ru


--- Comment #1 from Maxim Fomin <maxim@maxim-fomin.ru> 2013-09-11 13:22:37 PDT ---
f is not a function but a function pointer, so the issue is against current design and description of the issue is also misleading by the way.

By the way, this is a good opportunity to raise the question about what 'is' expression should return. There are currently two kinds 'function' and 'delegate' for three cases - a function, function pointer and delegate. Currently 'function' maps to function, not to a pointer and 'delegate' maps to delegate which is inconsistent (there is also inconsistency with not mapping 'function' to function pointer as this keyword is related to function pointers in other use cases).

If 'function' should map to both pointer and a function, then there should be some means to distingiush between them. Another option is to map 'function' to pointer and function should map to returned type .

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