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use crate::infer::error_reporting::nice_region_error::find_anon_type;
use rustc_errors::{
self, fluent, AddToDiagnostic, Diagnostic, IntoDiagnosticArg, SubdiagnosticMessage,
};
use rustc_middle::ty::{self, TyCtxt};
use rustc_span::{symbol::kw, Span};
#[derive(Default)]
struct DescriptionCtx<'a> {
span: Option<Span>,
kind: &'a str,
arg: String,
num_arg: u32,
}
impl<'a> DescriptionCtx<'a> {
fn new<'tcx>(
tcx: TyCtxt<'tcx>,
region: ty::Region<'tcx>,
alt_span: Option<Span>,
) -> Option<Self> {
let mut me = DescriptionCtx::default();
me.span = alt_span;
match *region {
ty::ReEarlyBound(_) | ty::ReFree(_) => {
return Self::from_early_bound_and_free_regions(tcx, region);
}
ty::ReStatic => {
me.kind = "restatic";
}
ty::RePlaceholder(_) => return None,
ty::ReVar(_) | ty::ReLateBound(..) | ty::ReErased => {
me.kind = "revar";
me.arg = format!("{:?}", region);
}
};
Some(me)
}
fn from_early_bound_and_free_regions<'tcx>(
tcx: TyCtxt<'tcx>,
region: ty::Region<'tcx>,
) -> Option<Self> {
let mut me = DescriptionCtx::default();
let scope = region.free_region_binding_scope(tcx).expect_local();
match *region {
ty::ReEarlyBound(ref br) => {
let mut sp = tcx.def_span(scope);
if let Some(param) =
tcx.hir().get_generics(scope).and_then(|generics| generics.get_named(br.name))
{
sp = param.span;
}
if br.has_name() {
me.kind = "as_defined";
me.arg = br.name.to_string();
} else {
me.kind = "as_defined_anon";
};
me.span = Some(sp)
}
ty::ReFree(ref fr) => {
if !fr.bound_region.is_named()
&& let Some((ty, _)) = find_anon_type(tcx, region, &fr.bound_region)
{
me.kind = "defined_here";
me.span = Some(ty.span);
} else {
match fr.bound_region {
ty::BoundRegionKind::BrNamed(_, name) => {
let mut sp = tcx.def_span(scope);
if let Some(param) =
tcx.hir().get_generics(scope).and_then(|generics| generics.get_named(name))
{
sp = param.span;
}
if name == kw::UnderscoreLifetime {
me.kind = "as_defined_anon";
} else {
me.kind = "as_defined";
me.arg = name.to_string();
};
me.span = Some(sp);
}
ty::BrAnon(idx, span) => {
me.kind = "anon_num_here";
me.num_arg = idx+1;
me.span = match span {
Some(_) => span,
None => Some(tcx.def_span(scope)),
}
},
_ => {
me.kind = "defined_here_reg";
me.arg = region.to_string();
me.span = Some(tcx.def_span(scope));
},
}
}
}
_ => bug!(),
}
Some(me)
}
fn add_to(self, diag: &mut rustc_errors::Diagnostic) {
diag.set_arg("desc_kind", self.kind);
diag.set_arg("desc_arg", self.arg);
diag.set_arg("desc_num_arg", self.num_arg);
}
}
pub enum PrefixKind {
Empty,
}
pub enum SuffixKind {
Continues,
}
impl IntoDiagnosticArg for PrefixKind {
fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
let kind = match self {
Self::Empty => "empty",
}
.into();
rustc_errors::DiagnosticArgValue::Str(kind)
}
}
impl IntoDiagnosticArg for SuffixKind {
fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
let kind = match self {
Self::Continues => "continues",
}
.into();
rustc_errors::DiagnosticArgValue::Str(kind)
}
}
pub struct RegionExplanation<'a> {
desc: DescriptionCtx<'a>,
prefix: PrefixKind,
suffix: SuffixKind,
}
impl RegionExplanation<'_> {
pub fn new<'tcx>(
tcx: TyCtxt<'tcx>,
region: ty::Region<'tcx>,
alt_span: Option<Span>,
prefix: PrefixKind,
suffix: SuffixKind,
) -> Option<Self> {
Some(Self { desc: DescriptionCtx::new(tcx, region, alt_span)?, prefix, suffix })
}
}
impl AddToDiagnostic for RegionExplanation<'_> {
fn add_to_diagnostic_with<F>(self, diag: &mut Diagnostic, _: F)
where
F: Fn(&mut Diagnostic, SubdiagnosticMessage) -> SubdiagnosticMessage,
{
if let Some(span) = self.desc.span {
diag.span_note(span, fluent::infer_region_explanation);
} else {
diag.note(fluent::infer_region_explanation);
}
self.desc.add_to(diag);
diag.set_arg("pref_kind", self.prefix);
diag.set_arg("suff_kind", self.suffix);
}
}