[Issue 16573] New: string-typed enum values pass isSomeString but not isInputRange

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=16573

          Issue ID: 16573
           Summary: string-typed enum values pass isSomeString but not
                    isInputRange
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: phobos
          Assignee: nobody at puremagic.com
          Reporter: ryan at rcorre.net

---
import std.traits, std.range;
enum S { foo = "foo" }
static assert(isSomeString!S); // true
static assert(isInputRange!S); // false
---

I would expect that all strings are input ranges, so this result is confusing.
In particular, it caused code to break when
https://github.com/dlang/phobos/pull/3447 was merged.

The following used to work:
---
enum S { foo = "foo" }
import std.file;
assert(S.foo.exists);
---

The PR range-ified std.file.exists, which should still allow it to accept all
the same types it did before. However, it now fails for S.foo as it is a string
but not a range. I think S.foo should either be both a string and a range, or
neither.

Related: https://issues.dlang.org/show_bug.cgi?id=8508

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