Fix Issue 930 - Templates inside templates used as mixins

[RazvanN7]

template ATemplate(T) {
   template ATemplate() {
       void foo() {
           T x = 2; // this line causes an error
           printf("Hi\n");
       }
   }
}

class TheClass(alias MixIt)
{
    mixin MixIt;
}


void main()
{
    auto val = new TheClass!(ATemplate!(int));
    val.foo();
}

When a template is instantiated, the template parameters are declared as aliases to the instantiation types in the scope of the template instance. In this situation, the mixin simply syntax copies the Atemplate() without any knowledge of its parent scope, therefore the alias for the T type is lost.

My patch checks for this particular case and the lost types are brought in the mixin scope.

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	930	minor	Templates inside templates used as mixins

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub fetch digger
dub run digger -- build "stable + dmd#10192"

[thewilsonator]

This is a pretty simple fix, might as well target stable.

[RazvanN7]

Fair enough.

[ghost]

You can declare a dummy function with the same signature as printf.

[RazvanN7]

I could delete it altogether, I just wanted to preserve the initial bug report as is.

[ghost]

and get ridof the import in case it was not clear

[ghost]

I could delete it altogether, I just wanted to preserve the initial bug report as is

yes sorry crossed post. Remove the import and use local dummy please and it's good.

[RazvanN7]

I deleted the printf; it's a compilable test anyway.

[ghost]

LGTM