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
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188

use crate::{ImportKind, NameBindingKind, Resolver};
use rustc_ast::ast;
use rustc_ast::visit;
use rustc_ast::visit::Visitor;
use rustc_ast::Crate;
use rustc_ast::EnumDef;
use rustc_hir::def_id::LocalDefId;
use rustc_hir::def_id::CRATE_DEF_ID;
use rustc_middle::middle::privacy::Level;
use rustc_middle::ty::{DefIdTree, Visibility};

pub struct EffectiveVisibilitiesVisitor<'r, 'a> {
    r: &'r mut Resolver<'a>,
    changed: bool,
}

impl<'r, 'a> EffectiveVisibilitiesVisitor<'r, 'a> {
    /// Fills the `Resolver::effective_visibilities` table with public & exported items
    /// For now, this doesn't resolve macros (FIXME) and cannot resolve Impl, as we
    /// need access to a TyCtxt for that.
    pub fn compute_effective_visibilities<'c>(r: &'r mut Resolver<'a>, krate: &'c Crate) {
        let mut visitor = EffectiveVisibilitiesVisitor { r, changed: false };

        visitor.update(CRATE_DEF_ID, Visibility::Public, CRATE_DEF_ID, Level::Direct);
        visitor.set_bindings_effective_visibilities(CRATE_DEF_ID);

        while visitor.changed {
            visitor.reset();
            visit::walk_crate(&mut visitor, krate);
        }

        info!("resolve::effective_visibilities: {:#?}", r.effective_visibilities);
    }

    fn reset(&mut self) {
        self.changed = false;
    }

    /// Update effective visibilities of bindings in the given module,
    /// including their whole reexport chains.
    fn set_bindings_effective_visibilities(&mut self, module_id: LocalDefId) {
        assert!(self.r.module_map.contains_key(&&module_id.to_def_id()));
        let module = self.r.get_module(module_id.to_def_id()).unwrap();
        let resolutions = self.r.resolutions(module);

        for (_, name_resolution) in resolutions.borrow().iter() {
            if let Some(mut binding) = name_resolution.borrow().binding() && !binding.is_ambiguity() {
                // Set the given effective visibility level to `Level::Direct` and
                // sets the rest of the `use` chain to `Level::Reexported` until
                // we hit the actual exported item.

                // FIXME: tag and is_public() condition should be removed, but assertions occur.
                let tag = if binding.is_import() { Level::Reexported } else { Level::Direct };
                if binding.vis.is_public() {
                    let mut prev_parent_id = module_id;
                    let mut level = Level::Direct;
                    while let NameBindingKind::Import { binding: nested_binding, import, .. } =
                        binding.kind
                    {
                        let mut update = |node_id| self.update(
                            self.r.local_def_id(node_id),
                            binding.vis.expect_local(),
                            prev_parent_id,
                            level,
                        );
                        // In theory all the import IDs have individual visibilities and effective
                        // visibilities, but in practice these IDs go straigth to HIR where all
                        // their few uses assume that their (effective) visibility applies to the
                        // whole syntactic `use` item. So we update them all to the maximum value
                        // among the potential individual effective visibilities. Maybe HIR for
                        // imports shouldn't use three IDs at all.
                        update(import.id);
                        if let ImportKind::Single { additional_ids, .. } = import.kind {
                            update(additional_ids.0);
                            update(additional_ids.1);
                        }

                        level = Level::Reexported;
                        prev_parent_id = self.r.local_def_id(import.id);
                        binding = nested_binding;
                    }
                }

                if let Some(def_id) = binding.res().opt_def_id().and_then(|id| id.as_local()) {
                    self.update(def_id, binding.vis.expect_local(), module_id, tag);
                }
            }
        }
    }

    fn update(
        &mut self,
        def_id: LocalDefId,
        nominal_vis: Visibility,
        parent_id: LocalDefId,
        tag: Level,
    ) {
        let module_id = self
            .r
            .get_nearest_non_block_module(def_id.to_def_id())
            .nearest_parent_mod()
            .expect_local();
        if nominal_vis == Visibility::Restricted(module_id)
            || self.r.visibilities[&parent_id] == Visibility::Restricted(module_id)
        {
            return;
        }
        let mut effective_visibilities = std::mem::take(&mut self.r.effective_visibilities);
        self.changed |= effective_visibilities.update(
            def_id,
            nominal_vis,
            || Visibility::Restricted(module_id),
            parent_id,
            tag,
            &*self.r,
        );
        self.r.effective_visibilities = effective_visibilities;
    }
}

impl<'r, 'ast> Visitor<'ast> for EffectiveVisibilitiesVisitor<'ast, 'r> {
    fn visit_item(&mut self, item: &'ast ast::Item) {
        let def_id = self.r.local_def_id(item.id);
        // Update effective visibilities of nested items.
        // If it's a mod, also make the visitor walk all of its items
        match item.kind {
            // Resolved in rustc_privacy when types are available
            ast::ItemKind::Impl(..) => return,

            // Should be unreachable at this stage
            ast::ItemKind::MacCall(..) => panic!(
                "ast::ItemKind::MacCall encountered, this should not anymore appear at this stage"
            ),

            // Foreign modules inherit level from parents.
            ast::ItemKind::ForeignMod(..) => {
                let parent_id = self.r.local_parent(def_id);
                self.update(def_id, Visibility::Public, parent_id, Level::Direct);
            }

            // Only exported `macro_rules!` items are public, but they always are
            ast::ItemKind::MacroDef(ref macro_def) if macro_def.macro_rules => {
                let parent_id = self.r.local_parent(def_id);
                let vis = self.r.visibilities[&def_id];
                self.update(def_id, vis, parent_id, Level::Direct);
            }

            ast::ItemKind::Mod(..) => {
                self.set_bindings_effective_visibilities(def_id);
                visit::walk_item(self, item);
            }

            ast::ItemKind::Enum(EnumDef { ref variants }, _) => {
                self.set_bindings_effective_visibilities(def_id);
                for variant in variants {
                    let variant_def_id = self.r.local_def_id(variant.id);
                    for field in variant.data.fields() {
                        let field_def_id = self.r.local_def_id(field.id);
                        let vis = self.r.visibilities[&field_def_id];
                        self.update(field_def_id, vis, variant_def_id, Level::Direct);
                    }
                }
            }

            ast::ItemKind::Struct(ref def, _) | ast::ItemKind::Union(ref def, _) => {
                for field in def.fields() {
                    let field_def_id = self.r.local_def_id(field.id);
                    let vis = self.r.visibilities[&field_def_id];
                    self.update(field_def_id, vis, def_id, Level::Direct);
                }
            }

            ast::ItemKind::Trait(..) => {
                self.set_bindings_effective_visibilities(def_id);
            }

            ast::ItemKind::ExternCrate(..)
            | ast::ItemKind::Use(..)
            | ast::ItemKind::Static(..)
            | ast::ItemKind::Const(..)
            | ast::ItemKind::GlobalAsm(..)
            | ast::ItemKind::TyAlias(..)
            | ast::ItemKind::TraitAlias(..)
            | ast::ItemKind::MacroDef(..)
            | ast::ItemKind::Fn(..) => return,
        }
    }
}