In the DMD compiler frontend, the type TypeFunction (cf. astbase.d) representing a function type has a linkage member. Setting this member when parsing seems to have no effect. How do I set the linkage of a function type?

For alias declarations which support setting function type linkage, in parse.d, it creates a LinkageDeclaration, which I cannot do because my function type is not declared, but (potentially) nested in something else.

My overall goal is to allow linkage as part of a function pointer / delegate type:

void f(extern(C) void function() cFunctionPtr) { }
alias CFP = extern(C) void function();
void g(CFP cFunctionPtr) { }

I can already parse this, but pragma(msg, typeof(&f), '\n', typeof(&g)) gives me:

void function(void function() cFunctionPtr)
void function((extern (C) void function()) cFunctionPtr)

This shows that the linkage of f’s parameter is not seen somehow, but when the linkage is seen, it properly does end up in the parameter’s type.