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use crate::Upvar;
use crate::{nll::ToRegionVid, region_infer::RegionInferenceContext};
use rustc_index::vec::{Idx, IndexVec};
use rustc_middle::mir::{Body, Local};
use rustc_middle::ty::{RegionVid, TyCtxt};
use rustc_span::source_map::Span;
use rustc_span::symbol::Symbol;
impl<'tcx> RegionInferenceContext<'tcx> {
crate fn get_var_name_and_span_for_region(
&self,
tcx: TyCtxt<'tcx>,
body: &Body<'tcx>,
local_names: &IndexVec<Local, Option<Symbol>>,
upvars: &[Upvar<'tcx>],
fr: RegionVid,
) -> Option<(Option<Symbol>, Span)> {
debug!("get_var_name_and_span_for_region(fr={:?})", fr);
assert!(self.universal_regions().is_universal_region(fr));
debug!("get_var_name_and_span_for_region: attempting upvar");
self.get_upvar_index_for_region(tcx, fr)
.map(|index| {
// FIXME(project-rfc-2229#8): Use place span for diagnostics
let (name, span) = self.get_upvar_name_and_span_for_region(tcx, upvars, index);
(Some(name), span)
})
.or_else(|| {
debug!("get_var_name_and_span_for_region: attempting argument");
self.get_argument_index_for_region(tcx, fr).map(|index| {
self.get_argument_name_and_span_for_region(body, local_names, index)
})
})
}
/// Search the upvars (if any) to find one that references fr. Return its index.
crate fn get_upvar_index_for_region(&self, tcx: TyCtxt<'tcx>, fr: RegionVid) -> Option<usize> {
let upvar_index =
self.universal_regions().defining_ty.upvar_tys().position(|upvar_ty| {
debug!("get_upvar_index_for_region: upvar_ty={:?}", upvar_ty);
tcx.any_free_region_meets(&upvar_ty, |r| {
let r = r.to_region_vid();
debug!("get_upvar_index_for_region: r={:?} fr={:?}", r, fr);
r == fr
})
})?;
let upvar_ty = self.universal_regions().defining_ty.upvar_tys().nth(upvar_index);
debug!(
"get_upvar_index_for_region: found {:?} in upvar {} which has type {:?}",
fr, upvar_index, upvar_ty,
);
Some(upvar_index)
}
/// Given the index of an upvar, finds its name and the span from where it was
/// declared.
crate fn get_upvar_name_and_span_for_region(
&self,
tcx: TyCtxt<'tcx>,
upvars: &[Upvar<'tcx>],
upvar_index: usize,
) -> (Symbol, Span) {
let upvar_hir_id = upvars[upvar_index].place.get_root_variable();
debug!("get_upvar_name_and_span_for_region: upvar_hir_id={:?}", upvar_hir_id);
let upvar_name = tcx.hir().name(upvar_hir_id);
let upvar_span = tcx.hir().span(upvar_hir_id);
debug!(
"get_upvar_name_and_span_for_region: upvar_name={:?} upvar_span={:?}",
upvar_name, upvar_span
);
(upvar_name, upvar_span)
}
/// Search the argument types for one that references fr (which should be a free region).
/// Returns Some(_) with the index of the input if one is found.
///
/// N.B., in the case of a closure, the index is indexing into the signature as seen by the
/// user - in particular, index 0 is not the implicit self parameter.
crate fn get_argument_index_for_region(
&self,
tcx: TyCtxt<'tcx>,
fr: RegionVid,
) -> Option<usize> {
let implicit_inputs = self.universal_regions().defining_ty.implicit_inputs();
let argument_index =
self.universal_regions().unnormalized_input_tys.iter().skip(implicit_inputs).position(
|arg_ty| {
debug!("get_argument_index_for_region: arg_ty = {:?}", arg_ty);
tcx.any_free_region_meets(arg_ty, |r| r.to_region_vid() == fr)
},
)?;
debug!(
"get_argument_index_for_region: found {:?} in argument {} which has type {:?}",
fr,
argument_index,
self.universal_regions().unnormalized_input_tys[argument_index],
);
Some(argument_index)
}
/// Given the index of an argument, finds its name (if any) and the span from where it was
/// declared.
crate fn get_argument_name_and_span_for_region(
&self,
body: &Body<'tcx>,
local_names: &IndexVec<Local, Option<Symbol>>,
argument_index: usize,
) -> (Option<Symbol>, Span) {
let implicit_inputs = self.universal_regions().defining_ty.implicit_inputs();
let argument_local = Local::new(implicit_inputs + argument_index + 1);
debug!("get_argument_name_and_span_for_region: argument_local={:?}", argument_local);
let argument_name = local_names[argument_local];
let argument_span = body.local_decls[argument_local].source_info.span;
debug!(
"get_argument_name_and_span_for_region: argument_name={:?} argument_span={:?}",
argument_name, argument_span
);
(argument_name, argument_span)
}
}
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