rustc_middle/thir/
visit.rs

1use super::{
2    AdtExpr, AdtExprBase, Arm, Block, ClosureExpr, Expr, ExprKind, InlineAsmExpr, InlineAsmOperand,
3    Pat, PatKind, Stmt, StmtKind, Thir,
4};
5use crate::thir::LoopMatchMatchData;
6
7/// Every `walk_*` method uses deconstruction to access fields of structs and
8/// enums. This will result in a compile error if a field is added, which makes
9/// it more likely the appropriate visit call will be added for it.
10pub trait Visitor<'thir, 'tcx: 'thir>: Sized {
11    fn thir(&self) -> &'thir Thir<'tcx>;
12
13    fn visit_expr(&mut self, expr: &'thir Expr<'tcx>) {
14        walk_expr(self, expr);
15    }
16
17    fn visit_stmt(&mut self, stmt: &'thir Stmt<'tcx>) {
18        walk_stmt(self, stmt);
19    }
20
21    fn visit_block(&mut self, block: &'thir Block) {
22        walk_block(self, block);
23    }
24
25    fn visit_arm(&mut self, arm: &'thir Arm<'tcx>) {
26        walk_arm(self, arm);
27    }
28
29    fn visit_pat(&mut self, pat: &'thir Pat<'tcx>) {
30        walk_pat(self, pat);
31    }
32
33    // Note: We don't have visitors for `ty::Const` and `mir::Const`
34    // (even though these types occur in THIR) for consistency and to reduce confusion,
35    // since the lazy creation of constants during thir construction causes most
36    // 'constants' to not be of type `ty::Const` or `mir::Const` at that
37    // stage (they are mostly still identified by `DefId` or `hir::Lit`, see
38    // the variants `Literal`, `NonHirLiteral` and `NamedConst` in `thir::ExprKind`).
39    // You have to manually visit `ty::Const` and `mir::Const` through the
40    // other `visit*` functions.
41}
42
43pub fn walk_expr<'thir, 'tcx: 'thir, V: Visitor<'thir, 'tcx>>(
44    visitor: &mut V,
45    expr: &'thir Expr<'tcx>,
46) {
47    use ExprKind::*;
48    let Expr { kind, ty: _, temp_scope_id: _, span: _ } = expr;
49    match *kind {
50        Scope { value, region_scope: _, hir_id: _ } => visitor.visit_expr(&visitor.thir()[value]),
51        If { cond, then, else_opt, if_then_scope: _ } => {
52            visitor.visit_expr(&visitor.thir()[cond]);
53            visitor.visit_expr(&visitor.thir()[then]);
54            if let Some(else_expr) = else_opt {
55                visitor.visit_expr(&visitor.thir()[else_expr]);
56            }
57        }
58        Call { fun, ref args, ty: _, from_hir_call: _, fn_span: _ } => {
59            visitor.visit_expr(&visitor.thir()[fun]);
60            for &arg in &**args {
61                visitor.visit_expr(&visitor.thir()[arg]);
62            }
63        }
64        ByUse { expr, span: _ } => {
65            visitor.visit_expr(&visitor.thir()[expr]);
66        }
67        Deref { arg } => visitor.visit_expr(&visitor.thir()[arg]),
68        Binary { lhs, rhs, op: _ } | LogicalOp { lhs, rhs, op: _ } => {
69            visitor.visit_expr(&visitor.thir()[lhs]);
70            visitor.visit_expr(&visitor.thir()[rhs]);
71        }
72        Unary { arg, op: _ } => visitor.visit_expr(&visitor.thir()[arg]),
73        Cast { source } => visitor.visit_expr(&visitor.thir()[source]),
74        Use { source } => visitor.visit_expr(&visitor.thir()[source]),
75        NeverToAny { source } => visitor.visit_expr(&visitor.thir()[source]),
76        PointerCoercion { source, cast: _, is_from_as_cast: _ } => {
77            visitor.visit_expr(&visitor.thir()[source])
78        }
79        Let { expr, ref pat } => {
80            visitor.visit_expr(&visitor.thir()[expr]);
81            visitor.visit_pat(pat);
82        }
83        Loop { body } => visitor.visit_expr(&visitor.thir()[body]),
84        LoopMatch { match_data: box LoopMatchMatchData { scrutinee, ref arms, .. }, .. }
85        | Match { scrutinee, ref arms, .. } => {
86            visitor.visit_expr(&visitor.thir()[scrutinee]);
87            for &arm in &**arms {
88                visitor.visit_arm(&visitor.thir()[arm]);
89            }
90        }
91        Block { block } => visitor.visit_block(&visitor.thir()[block]),
92        Assign { lhs, rhs } | AssignOp { lhs, rhs, op: _ } => {
93            visitor.visit_expr(&visitor.thir()[lhs]);
94            visitor.visit_expr(&visitor.thir()[rhs]);
95        }
96        Field { lhs, variant_index: _, name: _ } => visitor.visit_expr(&visitor.thir()[lhs]),
97        Index { lhs, index } => {
98            visitor.visit_expr(&visitor.thir()[lhs]);
99            visitor.visit_expr(&visitor.thir()[index]);
100        }
101        VarRef { id: _ } | UpvarRef { closure_def_id: _, var_hir_id: _ } => {}
102        Borrow { arg, borrow_kind: _ } => visitor.visit_expr(&visitor.thir()[arg]),
103        RawBorrow { arg, mutability: _ } => visitor.visit_expr(&visitor.thir()[arg]),
104        Break { value, label: _ } => {
105            if let Some(value) = value {
106                visitor.visit_expr(&visitor.thir()[value])
107            }
108        }
109        Continue { label: _ } => {}
110        ConstContinue { value, label: _ } => visitor.visit_expr(&visitor.thir()[value]),
111        Return { value } => {
112            if let Some(value) = value {
113                visitor.visit_expr(&visitor.thir()[value])
114            }
115        }
116        Become { value } => visitor.visit_expr(&visitor.thir()[value]),
117        ConstBlock { did: _, args: _ } => {}
118        Repeat { value, count: _ } => {
119            visitor.visit_expr(&visitor.thir()[value]);
120        }
121        Array { ref fields } | Tuple { ref fields } => {
122            for &field in &**fields {
123                visitor.visit_expr(&visitor.thir()[field]);
124            }
125        }
126        Adt(box AdtExpr {
127            ref fields,
128            ref base,
129            adt_def: _,
130            variant_index: _,
131            args: _,
132            user_ty: _,
133        }) => {
134            for field in &**fields {
135                visitor.visit_expr(&visitor.thir()[field.expr]);
136            }
137            if let AdtExprBase::Base(base) = base {
138                visitor.visit_expr(&visitor.thir()[base.base]);
139            }
140        }
141        PlaceTypeAscription { source, user_ty: _, user_ty_span: _ }
142        | ValueTypeAscription { source, user_ty: _, user_ty_span: _ } => {
143            visitor.visit_expr(&visitor.thir()[source])
144        }
145        PlaceUnwrapUnsafeBinder { source }
146        | ValueUnwrapUnsafeBinder { source }
147        | WrapUnsafeBinder { source } => visitor.visit_expr(&visitor.thir()[source]),
148        Closure(box ClosureExpr {
149            closure_id: _,
150            args: _,
151            upvars: _,
152            movability: _,
153            fake_reads: _,
154        }) => {}
155        Literal { lit: _, neg: _ } => {}
156        NonHirLiteral { lit: _, user_ty: _ } => {}
157        ZstLiteral { user_ty: _ } => {}
158        NamedConst { def_id: _, args: _, user_ty: _ } => {}
159        ConstParam { param: _, def_id: _ } => {}
160        StaticRef { alloc_id: _, ty: _, def_id: _ } => {}
161        InlineAsm(box InlineAsmExpr {
162            asm_macro: _,
163            ref operands,
164            template: _,
165            options: _,
166            line_spans: _,
167        }) => {
168            for op in &**operands {
169                use InlineAsmOperand::*;
170                match op {
171                    In { expr, reg: _ }
172                    | Out { expr: Some(expr), reg: _, late: _ }
173                    | InOut { expr, reg: _, late: _ } => visitor.visit_expr(&visitor.thir()[*expr]),
174                    SplitInOut { in_expr, out_expr, reg: _, late: _ } => {
175                        visitor.visit_expr(&visitor.thir()[*in_expr]);
176                        if let Some(out_expr) = out_expr {
177                            visitor.visit_expr(&visitor.thir()[*out_expr]);
178                        }
179                    }
180                    Out { expr: None, reg: _, late: _ }
181                    | Const { value: _, span: _ }
182                    | SymFn { value: _ }
183                    | SymStatic { def_id: _ } => {}
184                    Label { block } => visitor.visit_block(&visitor.thir()[*block]),
185                }
186            }
187        }
188        ThreadLocalRef(_) => {}
189        Yield { value } => visitor.visit_expr(&visitor.thir()[value]),
190    }
191}
192
193pub fn walk_stmt<'thir, 'tcx: 'thir, V: Visitor<'thir, 'tcx>>(
194    visitor: &mut V,
195    stmt: &'thir Stmt<'tcx>,
196) {
197    let Stmt { kind } = stmt;
198    match kind {
199        StmtKind::Expr { expr, scope: _ } => visitor.visit_expr(&visitor.thir()[*expr]),
200        StmtKind::Let {
201            initializer,
202            remainder_scope: _,
203            init_scope: _,
204            pattern,
205            hir_id: _,
206            else_block,
207            span: _,
208        } => {
209            if let Some(init) = initializer {
210                visitor.visit_expr(&visitor.thir()[*init]);
211            }
212            visitor.visit_pat(pattern);
213            if let Some(block) = else_block {
214                visitor.visit_block(&visitor.thir()[*block])
215            }
216        }
217    }
218}
219
220pub fn walk_block<'thir, 'tcx: 'thir, V: Visitor<'thir, 'tcx>>(
221    visitor: &mut V,
222    block: &'thir Block,
223) {
224    let Block { stmts, expr, targeted_by_break: _, region_scope: _, span: _, safety_mode: _ } =
225        block;
226    for &stmt in &*stmts {
227        visitor.visit_stmt(&visitor.thir()[stmt]);
228    }
229    if let Some(expr) = expr {
230        visitor.visit_expr(&visitor.thir()[*expr]);
231    }
232}
233
234pub fn walk_arm<'thir, 'tcx: 'thir, V: Visitor<'thir, 'tcx>>(
235    visitor: &mut V,
236    arm: &'thir Arm<'tcx>,
237) {
238    let Arm { guard, pattern, body, hir_id: _, span: _, scope: _ } = arm;
239    if let Some(expr) = guard {
240        visitor.visit_expr(&visitor.thir()[*expr])
241    }
242    visitor.visit_pat(pattern);
243    visitor.visit_expr(&visitor.thir()[*body]);
244}
245
246pub fn walk_pat<'thir, 'tcx: 'thir, V: Visitor<'thir, 'tcx>>(
247    visitor: &mut V,
248    pat: &'thir Pat<'tcx>,
249) {
250    for_each_immediate_subpat(pat, |p| visitor.visit_pat(p));
251}
252
253/// Invokes `callback` on each immediate subpattern of `pat`, if any.
254/// A building block for assembling THIR pattern visitors.
255pub(crate) fn for_each_immediate_subpat<'a, 'tcx>(
256    pat: &'a Pat<'tcx>,
257    mut callback: impl FnMut(&'a Pat<'tcx>),
258) {
259    let Pat { kind, ty: _, span: _, extra: _ } = pat;
260    match kind {
261        PatKind::Missing
262        | PatKind::Wild
263        | PatKind::Binding { subpattern: None, .. }
264        | PatKind::Constant { value: _ }
265        | PatKind::Range(_)
266        | PatKind::Never
267        | PatKind::Error(_) => {}
268
269        PatKind::Binding { subpattern: Some(subpattern), .. }
270        | PatKind::Deref { subpattern, .. }
271        | PatKind::DerefPattern { subpattern, .. } => callback(subpattern),
272
273        PatKind::Variant { subpatterns, .. } | PatKind::Leaf { subpatterns } => {
274            for field_pat in subpatterns {
275                callback(&field_pat.pattern);
276            }
277        }
278
279        PatKind::Slice { prefix, slice, suffix } | PatKind::Array { prefix, slice, suffix } => {
280            for pat in prefix.iter().chain(slice.as_deref()).chain(suffix) {
281                callback(pat);
282            }
283        }
284
285        PatKind::Or { pats } => {
286            for pat in pats {
287                callback(pat);
288            }
289        }
290    }
291}
rustc_middle/thir/visit.rs

rustc_middle/thir/
visit.rs
