|
| 1 | +use rustc_ast::ast::{LitFloatType, LitIntType, LitKind}; |
| 2 | +use rustc_errors::Applicability; |
| 3 | +use rustc_hir::{ |
| 4 | + intravisit::{walk_expr, walk_stmt, NestedVisitorMap, Visitor}, |
| 5 | + Body, Expr, ExprKind, HirId, Lit, Stmt, StmtKind, |
| 6 | +}; |
| 7 | +use rustc_lint::{LateContext, LateLintPass}; |
| 8 | +use rustc_middle::{ |
| 9 | + hir::map::Map, |
| 10 | + ty::{self, FloatTy, IntTy, PolyFnSig, Ty}, |
| 11 | +}; |
| 12 | +use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| 13 | + |
| 14 | +use if_chain::if_chain; |
| 15 | + |
| 16 | +use crate::utils::{snippet, span_lint_and_sugg}; |
| 17 | + |
| 18 | +declare_clippy_lint! { |
| 19 | + /// **What it does:** Checks for usage of unconstrained numeric literals which may cause default numeric fallback in type |
| 20 | + /// inference. |
| 21 | + /// |
| 22 | + /// Default numeric fallback means that if numeric types have not yet been bound to concrete |
| 23 | + /// types at the end of type inference, then integer type is bound to `i32`, and similarly |
| 24 | + /// floating type is bound to `f64`. |
| 25 | + /// |
| 26 | + /// See [RFC0212](https://github.com/rust-lang/rfcs/blob/master/text/0212-restore-int-fallback.md) for more information about the fallback. |
| 27 | + /// |
| 28 | + /// **Why is this bad?** For those who are very careful about types, default numeric fallback |
| 29 | + /// can be a pitfall that cause unexpected runtime behavior. |
| 30 | + /// |
| 31 | + /// **Known problems:** This lint can only be allowed at the function level or above. |
| 32 | + /// |
| 33 | + /// **Example:** |
| 34 | + /// ```rust |
| 35 | + /// let i = 10; |
| 36 | + /// let f = 1.23; |
| 37 | + /// ``` |
| 38 | + /// |
| 39 | + /// Use instead: |
| 40 | + /// ```rust |
| 41 | + /// let i = 10i32; |
| 42 | + /// let f = 1.23f64; |
| 43 | + /// ``` |
| 44 | + pub DEFAULT_NUMERIC_FALLBACK, |
| 45 | + restriction, |
| 46 | + "usage of unconstrained numeric literals which may cause default numeric fallback." |
| 47 | +} |
| 48 | + |
| 49 | +declare_lint_pass!(DefaultNumericFallback => [DEFAULT_NUMERIC_FALLBACK]); |
| 50 | + |
| 51 | +impl LateLintPass<'_> for DefaultNumericFallback { |
| 52 | + fn check_body(&mut self, cx: &LateContext<'tcx>, body: &'tcx Body<'_>) { |
| 53 | + let mut visitor = NumericFallbackVisitor::new(cx); |
| 54 | + visitor.visit_body(body); |
| 55 | + } |
| 56 | +} |
| 57 | + |
| 58 | +struct NumericFallbackVisitor<'a, 'tcx> { |
| 59 | + /// Stack manages type bound of exprs. The top element holds current expr type. |
| 60 | + ty_bounds: Vec<TyBound<'tcx>>, |
| 61 | + |
| 62 | + cx: &'a LateContext<'tcx>, |
| 63 | +} |
| 64 | + |
| 65 | +impl<'a, 'tcx> NumericFallbackVisitor<'a, 'tcx> { |
| 66 | + fn new(cx: &'a LateContext<'tcx>) -> Self { |
| 67 | + Self { |
| 68 | + ty_bounds: vec![TyBound::Nothing], |
| 69 | + cx, |
| 70 | + } |
| 71 | + } |
| 72 | + |
| 73 | + /// Check whether a passed literal has potential to cause fallback or not. |
| 74 | + fn check_lit(&self, lit: &Lit, lit_ty: Ty<'tcx>) { |
| 75 | + if_chain! { |
| 76 | + if let Some(ty_bound) = self.ty_bounds.last(); |
| 77 | + if matches!(lit.node, |
| 78 | + LitKind::Int(_, LitIntType::Unsuffixed) | LitKind::Float(_, LitFloatType::Unsuffixed)); |
| 79 | + if !ty_bound.is_integral(); |
| 80 | + then { |
| 81 | + let suffix = match lit_ty.kind() { |
| 82 | + ty::Int(IntTy::I32) => "i32", |
| 83 | + ty::Float(FloatTy::F64) => "f64", |
| 84 | + // Default numeric fallback never results in other types. |
| 85 | + _ => return, |
| 86 | + }; |
| 87 | + |
| 88 | + let sugg = format!("{}_{}", snippet(self.cx, lit.span, ""), suffix); |
| 89 | + span_lint_and_sugg( |
| 90 | + self.cx, |
| 91 | + DEFAULT_NUMERIC_FALLBACK, |
| 92 | + lit.span, |
| 93 | + "default numeric fallback might occur", |
| 94 | + "consider adding suffix", |
| 95 | + sugg, |
| 96 | + Applicability::MaybeIncorrect, |
| 97 | + ); |
| 98 | + } |
| 99 | + } |
| 100 | + } |
| 101 | +} |
| 102 | + |
| 103 | +impl<'a, 'tcx> Visitor<'tcx> for NumericFallbackVisitor<'a, 'tcx> { |
| 104 | + type Map = Map<'tcx>; |
| 105 | + |
| 106 | + #[allow(clippy::too_many_lines)] |
| 107 | + fn visit_expr(&mut self, expr: &'tcx Expr<'_>) { |
| 108 | + match &expr.kind { |
| 109 | + ExprKind::Call(func, args) => { |
| 110 | + if let Some(fn_sig) = fn_sig_opt(self.cx, func.hir_id) { |
| 111 | + for (expr, bound) in args.iter().zip(fn_sig.skip_binder().inputs().iter()) { |
| 112 | + // Push found arg type, then visit arg. |
| 113 | + self.ty_bounds.push(TyBound::Ty(bound)); |
| 114 | + self.visit_expr(expr); |
| 115 | + self.ty_bounds.pop(); |
| 116 | + } |
| 117 | + return; |
| 118 | + } |
| 119 | + }, |
| 120 | + |
| 121 | + ExprKind::MethodCall(_, _, args, _) => { |
| 122 | + if let Some(def_id) = self.cx.typeck_results().type_dependent_def_id(expr.hir_id) { |
| 123 | + let fn_sig = self.cx.tcx.fn_sig(def_id).skip_binder(); |
| 124 | + for (expr, bound) in args.iter().zip(fn_sig.inputs().iter()) { |
| 125 | + self.ty_bounds.push(TyBound::Ty(bound)); |
| 126 | + self.visit_expr(expr); |
| 127 | + self.ty_bounds.pop(); |
| 128 | + } |
| 129 | + return; |
| 130 | + } |
| 131 | + }, |
| 132 | + |
| 133 | + ExprKind::Struct(qpath, fields, base) => { |
| 134 | + if_chain! { |
| 135 | + if let Some(def_id) = self.cx.qpath_res(qpath, expr.hir_id).opt_def_id(); |
| 136 | + let ty = self.cx.tcx.type_of(def_id); |
| 137 | + if let Some(adt_def) = ty.ty_adt_def(); |
| 138 | + if adt_def.is_struct(); |
| 139 | + if let Some(variant) = adt_def.variants.iter().next(); |
| 140 | + then { |
| 141 | + let fields_def = &variant.fields; |
| 142 | + |
| 143 | + // Push field type then visit each field expr. |
| 144 | + for field in fields.iter() { |
| 145 | + let bound = |
| 146 | + fields_def |
| 147 | + .iter() |
| 148 | + .find_map(|f_def| { |
| 149 | + if f_def.ident == field.ident |
| 150 | + { Some(self.cx.tcx.type_of(f_def.did)) } |
| 151 | + else { None } |
| 152 | + }); |
| 153 | + self.ty_bounds.push(bound.into()); |
| 154 | + self.visit_expr(field.expr); |
| 155 | + self.ty_bounds.pop(); |
| 156 | + } |
| 157 | + |
| 158 | + // Visit base with no bound. |
| 159 | + if let Some(base) = base { |
| 160 | + self.ty_bounds.push(TyBound::Nothing); |
| 161 | + self.visit_expr(base); |
| 162 | + self.ty_bounds.pop(); |
| 163 | + } |
| 164 | + return; |
| 165 | + } |
| 166 | + } |
| 167 | + }, |
| 168 | + |
| 169 | + ExprKind::Lit(lit) => { |
| 170 | + let ty = self.cx.typeck_results().expr_ty(expr); |
| 171 | + self.check_lit(lit, ty); |
| 172 | + return; |
| 173 | + }, |
| 174 | + |
| 175 | + _ => {}, |
| 176 | + } |
| 177 | + |
| 178 | + walk_expr(self, expr); |
| 179 | + } |
| 180 | + |
| 181 | + fn visit_stmt(&mut self, stmt: &'tcx Stmt<'_>) { |
| 182 | + match stmt.kind { |
| 183 | + StmtKind::Local(local) => { |
| 184 | + if local.ty.is_some() { |
| 185 | + self.ty_bounds.push(TyBound::Any) |
| 186 | + } else { |
| 187 | + self.ty_bounds.push(TyBound::Nothing) |
| 188 | + } |
| 189 | + }, |
| 190 | + |
| 191 | + _ => self.ty_bounds.push(TyBound::Nothing), |
| 192 | + } |
| 193 | + |
| 194 | + walk_stmt(self, stmt); |
| 195 | + self.ty_bounds.pop(); |
| 196 | + } |
| 197 | + |
| 198 | + fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> { |
| 199 | + NestedVisitorMap::None |
| 200 | + } |
| 201 | +} |
| 202 | + |
| 203 | +fn fn_sig_opt<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<PolyFnSig<'tcx>> { |
| 204 | + let node_ty = cx.typeck_results().node_type_opt(hir_id)?; |
| 205 | + // We can't use `TyS::fn_sig` because it automatically performs substs, this may result in FNs. |
| 206 | + match node_ty.kind() { |
| 207 | + ty::FnDef(def_id, _) => Some(cx.tcx.fn_sig(*def_id)), |
| 208 | + ty::FnPtr(fn_sig) => Some(*fn_sig), |
| 209 | + _ => None, |
| 210 | + } |
| 211 | +} |
| 212 | + |
| 213 | +#[derive(Debug, Clone, Copy)] |
| 214 | +enum TyBound<'tcx> { |
| 215 | + Any, |
| 216 | + Ty(Ty<'tcx>), |
| 217 | + Nothing, |
| 218 | +} |
| 219 | + |
| 220 | +impl<'tcx> TyBound<'tcx> { |
| 221 | + fn is_integral(self) -> bool { |
| 222 | + match self { |
| 223 | + TyBound::Any => true, |
| 224 | + TyBound::Ty(t) => t.is_integral(), |
| 225 | + TyBound::Nothing => false, |
| 226 | + } |
| 227 | + } |
| 228 | +} |
| 229 | + |
| 230 | +impl<'tcx> From<Option<Ty<'tcx>>> for TyBound<'tcx> { |
| 231 | + fn from(v: Option<Ty<'tcx>>) -> Self { |
| 232 | + match v { |
| 233 | + Some(t) => TyBound::Ty(t), |
| 234 | + None => TyBound::Nothing, |
| 235 | + } |
| 236 | + } |
| 237 | +} |
0 commit comments