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Inline and remove DescriptionCtx::from_early_bound_and_free_regions.

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It has a single call site, and the code is clearer with all region kinds
handled in one function, instead of splitting the handling across two
functions.

The commit also changes `DescriptionCtx::new` to use a more declarative
style, instead of creating a default `DescriptionCtx` and modifying it,
which I find easier to read.
This commit is contained in:
Nicholas Nethercote 2023-04-11 17:14:41 +10:00
parent c9b0635679
commit 877777f5bc
1 changed files with 55 additions and 78 deletions
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133
compiler/rustc_infer/src/errors/note_and_explain.rs
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@ -4,7 +4,6 @@ use rustc_errors::{self, AddToDiagnostic, Diagnostic, IntoDiagnosticArg, Subdiag
use rustc_middle::ty::{self, TyCtxt};
use rustc_span::{symbol::kw, Span};
#[derive(Default)]
struct DescriptionCtx<'a> {
span: Option<Span>,
kind: &'a str,
@ -17,19 +16,63 @@ impl<'a> DescriptionCtx<'a> {
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);
let (span, kind, arg) = match *region {
ty::ReEarlyBound(ref br) => {
let scope = region.free_region_binding_scope(tcx).expect_local();
let span = if let Some(param) =
tcx.hir().get_generics(scope).and_then(|generics| generics.get_named(br.name))
{
param.span
} else {
tcx.def_span(scope)
};
if br.has_name() {
(Some(span), "as_defined", br.name.to_string())
} else {
(Some(span), "as_defined_anon", String::new())
}
}
ty::ReStatic => {
me.kind = "restatic";
ty::ReFree(ref fr) => {
if !fr.bound_region.is_named()
&& let Some((ty, _)) = find_anon_type(tcx, region, &fr.bound_region)
{
(Some(ty.span), "defined_here", String::new())
} else {
let scope = region.free_region_binding_scope(tcx).expect_local();
match fr.bound_region {
ty::BoundRegionKind::BrNamed(_, name) => {
let span = if let Some(param) = tcx
.hir()
.get_generics(scope)
.and_then(|generics| generics.get_named(name))
{
param.span
} else {
tcx.def_span(scope)
};
if name == kw::UnderscoreLifetime {
(Some(span), "as_defined_anon", String::new())
} else {
(Some(span), "as_defined", name.to_string())
}
}
ty::BrAnon(span) => {
let span = match span {
Some(_) => span,
None => Some(tcx.def_span(scope)),
};
(span, "defined_here", String::new())
}
_ => {
(Some(tcx.def_span(scope)), "defined_here_reg", region.to_string())
}
}
}
}
ty::RePlaceholder(_) => return None,
ty::ReStatic => (alt_span, "restatic", String::new()),
ty::ReError(_) => return None,
ty::RePlaceholder(_) | ty::ReError(_) => return None,
// FIXME(#13998) RePlaceholder should probably print like
// ReFree rather than dumping Debug output on the user.
@ -37,76 +80,10 @@ impl<'a> DescriptionCtx<'a> {
// We shouldn't really be having unification failures with ReVar
// and ReLateBound though.
ty::ReVar(_) | ty::ReLateBound(..) | ty::ReErased => {
me.kind = "revar";
me.arg = format!("{:?}", region);
(alt_span, "revar", 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(span) => {
me.kind = "defined_here";
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)
Some(DescriptionCtx { span, kind, arg })
}
}