On 4/19/22 9:36 AM, Andrey Zherikov wrote:
I want to migrate my library API from standalone function that takes
delegate as argument to a template member function that takes delegate
as a template parameter but compiler errors out. Here is code example:
```d
import std.stdio;
template T(P)
{
static void f_new(alias func)()
{
func();
}
}
void f(FUNC)(FUNC func)
{
T!int.f_new!(() => func());
}
void main()
{
f(function () { __LINE__.writeln; });
}
```
Compiler error:
```
onlineapp.d(7): Error: `static` function `onlineapp.f!(void function()
@safe).f.f_new!(delegate () @safe
{
(*func)();
return ;
}
).f_new` cannot access delegate `__lambda2` in frame of function
`onlineapp.f!(void function() @safe).f`
onlineapp.d(13): `__lambda2` declared here
onlineapp.d(13): Error: template instance `onlineapp.f!(void function()
@safe).f.f_new!(delegate () @safe
{
(*func)();
return ;
}
)` error instantiating
onlineapp.d(18): instantiated from here: `f!(void function() @safe)`
```
What confuses me a lot is that if I remove `template T` then everything
works perfectly:
```d
import std.stdio;
void f_new(alias func)()
{
func();
}
void f(FUNC)(FUNC func)
{
f_new!(() => func());
}
void main()
{
f(function () { __LINE__.writeln; });
}
```
Is there an issue in template processing in compiler?
Something similar just recently came up on discord. Maybe related:
https://issues.dlang.org/show_bug.cgi?id=17063
-Steve
