rustc_hir_analysis/variance/
dump.rs

1use std::fmt::Write;
2
3use rustc_hir::attrs::AttributeKind;
4use rustc_hir::def_id::{CRATE_DEF_ID, LocalDefId};
5use rustc_hir::find_attr;
6use rustc_middle::ty::{GenericArgs, TyCtxt};
7
8fn format_variances(tcx: TyCtxt<'_>, def_id: LocalDefId) -> String {
9    let variances = tcx.variances_of(def_id);
10    let generics = GenericArgs::identity_for_item(tcx, def_id);
11    // 7 = 2-letter parameter + ": " + 1-letter variance + ", "
12    let mut ret = String::with_capacity(2 + 7 * variances.len());
13    ret.push('[');
14    for (arg, variance) in generics.iter().zip(variances.iter()) {
15        ret.write_fmt(format_args!("{0}: {1:?}, ", arg, variance))write!(ret, "{arg}: {variance:?}, ").unwrap();
16    }
17    // Remove trailing `, `.
18    if !variances.is_empty() {
19        ret.pop();
20        ret.pop();
21    }
22    ret.push(']');
23    ret
24}
25
26pub(crate) fn variances(tcx: TyCtxt<'_>) {
27    let crate_items = tcx.hir_crate_items(());
28
29    if {
    {
            'done:
                {
                for i in tcx.get_all_attrs(CRATE_DEF_ID) {
                    let i: &rustc_hir::Attribute = i;
                    match i {
                        rustc_hir::Attribute::Parsed(AttributeKind::RustcVarianceOfOpaques)
                            => {
                            break 'done Some(());
                        }
                        _ => {}
                    }
                }
                None
            }
        }.is_some()
}find_attr!(tcx.get_all_attrs(CRATE_DEF_ID), AttributeKind::RustcVarianceOfOpaques) {
30        for id in crate_items.opaques() {
31            tcx.dcx().emit_err(crate::errors::VariancesOf {
32                span: tcx.def_span(id),
33                variances: format_variances(tcx, id),
34            });
35        }
36    }
37
38    for id in crate_items.free_items() {
39        if !{
    {
            'done:
                {
                for i in tcx.get_all_attrs(id.owner_id) {
                    let i: &rustc_hir::Attribute = i;
                    match i {
                        rustc_hir::Attribute::Parsed(AttributeKind::RustcVariance)
                            => {
                            break 'done Some(());
                        }
                        _ => {}
                    }
                }
                None
            }
        }.is_some()
}find_attr!(tcx.get_all_attrs(id.owner_id), AttributeKind::RustcVariance) {
40            continue;
41        }
42
43        tcx.dcx().emit_err(crate::errors::VariancesOf {
44            span: tcx.def_span(id.owner_id),
45            variances: format_variances(tcx, id.owner_id.def_id),
46        });
47    }
48}
rustc_hir_analysis/variance/dump.rs

rustc_hir_analysis/variance/
dump.rs
