isCallable fails

[frame]

On Wednesday, 20 January 2021 at 13:11:09 UTC, Paul Backus wrote:
> On Wednesday, 20 January 2021 at 04:43:12 UTC, frame wrote:
>> struct foo(T) {
>>   T get() {
>>         static if (is(T : bar)) {
>>             if (value is null) {
>>                 value = fun!T;
>
> Error: template instance `fun!T` template `fun` is not defined
>
> Please post an example with enough code to actually produce the 
> error you're seeing.

I don't know when to stop posting code then :(

fun!T just returns bar or null. Manually calling works.

but if it helps, here is fun!T:

TDobj fun(TDobj, T)(string propertyName, T needle) if (is(TDobj : 
bar)) {
    TDobj[] list = loadAllMatched!TDobj(propertyName, needle, 1);
    return list.length > 0 ? list[0] : null;
}

and actually called

value = fun!T("id", 123));

It also compiles if

value = new T