1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
#![deny(rustc::untranslatable_diagnostic)]
#![deny(rustc::diagnostic_outside_of_impl)]

use crate::region_infer::RegionInferenceContext;
use crate::Upvar;
use rustc_index::IndexSlice;
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> {
    pub(crate) fn get_var_name_and_span_for_region(
        &self,
        tcx: TyCtxt<'tcx>,
        body: &Body<'tcx>,
        local_names: &IndexSlice<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.
    pub(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().iter().position(|upvar_ty| {
                debug!("get_upvar_index_for_region: upvar_ty={upvar_ty:?}");
                tcx.any_free_region_meets(&upvar_ty, |r| {
                    let r = r.as_var();
                    debug!("get_upvar_index_for_region: r={r:?} fr={fr:?}");
                    r == fr
                })
            })?;

        let upvar_ty = self.universal_regions().defining_ty.upvar_tys().get(upvar_index);

        debug!(
            "get_upvar_index_for_region: found {fr:?} in upvar {upvar_index} which has type {upvar_ty:?}",
        );

        Some(upvar_index)
    }

    /// Given the index of an upvar, finds its name and the span from where it was
    /// declared.
    pub(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_name:?} upvar_span={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.
    pub(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.as_var() == fr)
                },
            )?;

        debug!(
            "get_argument_index_for_region: found {fr:?} in argument {argument_index} which has type {:?}",
            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.
    pub(crate) fn get_argument_name_and_span_for_region(
        &self,
        body: &Body<'tcx>,
        local_names: &IndexSlice<Local, Option<Symbol>>,
        argument_index: usize,
    ) -> (Option<Symbol>, Span) {
        let implicit_inputs = self.universal_regions().defining_ty.implicit_inputs();
        let argument_local = Local::from_usize(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_name:?} argument_span={argument_span:?}",
        );

        (argument_name, argument_span)
    }
}