• via Digitalmars-d-bugs (42/42) Jul 19 2016 https://issues.dlang.org/show_bug.cgi?id=16299

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

https://issues.dlang.org/show_bug.cgi?id=16299

          Issue ID: 16299
           Summary: Documentation for Phobos needs to warn about
                    autodecoding
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: dlang.org
          Assignee: nobody puremagic.com
          Reporter: wyatt.epp gmail.com

Problem:
The anomalous effects of autodecoding for Phobos functions are _effectively_
undocumented.  This means an innocent user has no warning that something like
std.algorithm.iteration.permutations will fail on an array of char[] (a very
common built-in type).  This is bad.

Possible fixes:
- Add warnings (with text _and_ links) that using char[] is going to screw
users:
    If using a char[] is going to break something, that should be mentioned in
the documentation for it.  There at least needs to be a generic warning that
stands out visually and links to further information on the autodecoding
problem and how to work around it.

- Add examples that show affected templates used on char[] and dchar[]:
    Most of the examples are conscripted unit tests using integers.

- Have the compiler explain the actual problem:
    Ugly? Maybe. Special casing is bad? Sure. But the current error is really
obtuse when you can do exactly what the example does only with a different type
and get "cannot deduce function from argument types".  That's way out of left
field.

- Make it actually work like it should:
    Especially if the input is known at compile time, autodecoding shouldn't
even be a problem.  But even at runtime, this should just work without fuss. 
Users shouldn't have to hunt down the documentation for template constraints if
they're not writing range types of their own; we made them grey because most
people _can_ ignore them.

See Also: 
Comments on issue #16263

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