wrong isInputRange design

[Jerry via Digitalmars-d]

On Saturday, 3 December 2016 at 11:52:00 UTC, rumbu wrote:
> import std.range.primitives: isInputRange;
>
> void test(R)(ref R range) if (isInputRange!R)
> {
>     auto c = r.front; //Error: no property 'front' for type 
> 'string'	
> }
>
> string s = "some string";
> test(s);
>
> The problem is that isInputRange will always return true for 
> string types (because it will check the availability of front, 
> popFront, empty through the entire std.range.primitives module.
>
> Since the only thing that was imported is std.range.primitives: 
> isInputRange, front is not available for strings.
>
> OK, the simple resolution is to import entirely 
> std.range.primitives, but the source of the problem was 
> another: I tried to define two overloads, one accepting 
> strings, and one accepting ranges;
>
> import std.range.primitives: isInputRange, ElementType;
> import std.traits: isSomeChar;
>
> void foo(C)(const(C)[] array) if (isSomeChar!C)
> {
>     //this will be never called	
> }
>
> void foo(R)(ref R range) if (isInputRange!R && 
> isSomeChar!(ElementType!R))
> {
>     //this will be always called
>     //any call to range.front, range.empty and so on will 
> result in error
> }
>
> foo(somestring)
>
> I expect foo!string to be called instead of foo!Range, because 
> in my context isInputRange!string should return false. Instead, 
> my context is hijacked by the definitions spread along 
> std.range.primitives module.
>
> The workaround I found is to define the second overload like 
> this:
>
> void foo(R)(ref R range) if (isInputRange!R && !isSomeString!R 
> && isSomeChar!(ElementType!R))

Is that the exact code? isInputRange checks to see if the type 
has "front" defined.

https://github.com/dlang/phobos/blob/v2.072.0/std/range/primitives.d#L162

Also "string" is just an alias of an array, "immutable(char)[]". 
So an array should have "front" defined. Can you post more code?