transpile: Unset needs_address in various places

[Rua]

needs_address is being set, but it is then passed down to all subexpressions, even those whose address is never actually taken.

[ahomescu]

I think is_pattern from 1776 has the same problem. We might need a larger refactoring to make all these context flags handle recursion correctly. It's weird though, all the mutators on ExprContext return Self so they should make a copy of the context and not modify the original, so what's going on here?

[Rua]

I think is_pattern from 1776 has the same problem. We might need a larger refactoring to make all these context flags handle recursion correctly.

I have already been looking into the overall issue. Some context flags should be "inherited", others should reset back to a default whenever they are passed to a subexpression.

It's weird though, all the mutators on ExprContext return Self so they should make a copy of the context and not modify the original, so what's going on here?

The problem isn't the copying, it's that the modified context of a parent expression gets passed to all the subexpressions too. So in this case, if needs_address is set when calling convert_expr or such, if the expression consists of further subexpressions, then needs_address will still be set when translating those subexpressions as well. You see this in the tests I've added: if the address is taken of an array-subscript expression, and either the array or the subscript are themselves expression types that are sensitive to the needs_address flag, then those expressions are also translated as if their address is taken, when they shouldn't be.

[ahomescu]

Do we want set_needs_address(false) for this one?

There might be a regression here for this test case:

int *deref_addrof_compound(void) {
    return *&(int[]){1, 2, 3};
}

Can you reproduce it?

[Rua]

I added a regression test for it and fixed the issue.

[ahomescu]

The problem isn't the copying, it's that the modified context of a parent expression gets passed to all the subexpressions too.

Ah I understand now, it's in the opposite direction of what I thought.