Hello, new dmd (2.100) has return/scope changes.
It look like examples at page https://dlang.org/spec/function.html#ref-return-scope-parameters are no longer relevant.

What difference are between return scope, scope return and return?
Why void* ptr in struct change effect of scope return ?

@safe:

struct A{
	int  val;
	//void* ptr;

	int* test() scope return{
		return &this.val;	// OK
	}
}

struct B{
	int  val;
	void* ptr;

	int* test() return{
		return &this.val; // OK
	}
}

struct C{
	int  val;
	void* ptr;

	int* test() scope return{
		return &this.val; // Error: returning `&this.val` escapes a reference to parameter `this`
	}
}


void main(){}

On Friday, 6 May 2022 at 09:24:06 UTC, vit wrote:

They were recently updated to match the implementation in 2.100.

return scope means pointer members (such this.ptr, C.ptr) may not escape the function, unless they are returned. If you call test() on a scope variable, the return value will be a scope pointer.

scope return on a struct member is scope + return ref, meaning pointer members may not escape the function (the scope part), but you can return a reference to the struct member itself (&this.val, the return ref part). If you call test() on a local variable (scope or not), the return value will be a scope pointer.

Just return allows you to return a reference to the struct member itself (&this.val), and also to escape pointer members (this.ptr) since there is no scope. However, that means you can't call test on scope variables.

	int* test() scope return{
		return &this.val; // Error: returning `&this.val` escapes a reference to parameter `this`
	}
}

I think you're using an older DMD version, the error should be gone in 2.100

scope is ignored when the struct has no pointers, and before 2.100, the meaning of return + scope on ref parameters was very inconsistent.

On Friday, 6 May 2022 at 17:17:01 UTC, Dennis wrote:

Thanks