Function rustc_hir_analysis::check::wfcheck::check_item

fn check_item<'tcx>(
    tcx: TyCtxt<'tcx>,
    item: &'tcx Item<'tcx>
) -> Result<(), ErrorGuaranteed>

Checks that the field types (in a struct def’n) or argument types (in an enum def’n) are well-formed, meaning that they do not require any constraints not declared in the struct definition itself. For example, this definition would be illegal:

struct Ref<'a, T> { x: &'a T }

because the type did not declare that T:'a.

We do this check as a pre-pass before checking fn bodies because if these constraints are not included it frequently leads to confusing errors in fn bodies. So it’s better to check the types first.