D template error with different types

original text

module foo;

mixin template opBi(A, A function(A, A)[string] f0,){
    
    static foreach (k, f; f0) {
     A opBinary(string op: k)(A r) {
     return f(this, r); } }
}

struct A {
    
    mixin opBi!(
        A, [ "+": (A a, A b) => a],
    );
}

struct B {
    
    mixin opBi!(
        B, [ "+": (B a, B b) => a],
    );
}

You can delete Some types And use typeof(this). Come on Pass on Correct type to f0.

module foo;

mixin template opBi(alias f0){
    
    static foreach (k, f; f0) {
     typeof(this) opBinary(string op:k)(typeof(this) r) {
     return f(this, r); } }
}

struct A {
    
    mixin opBi!(
        [ "+": (A a, A b) => a],
    );
}

struct B {
    
    mixin opBi!(
        [ "+": (B a, B b) => a],
    );
}

Incoming AA The type is T1[string], And the expectation is T2[string], among T1:B function(B, B) pure nothrow @nogc @safe,T2:B function(B, B).