--- /dev/null
+use rustc_ast::ast::{LitFloatType, LitIntType, LitKind};
+use rustc_errors::Applicability;
+use rustc_hir::{
+ intravisit::{walk_expr, walk_stmt, NestedVisitorMap, Visitor},
+ Body, Expr, ExprKind, HirId, Lit, Stmt, StmtKind,
+};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::{
+ hir::map::Map,
+ ty::{self, FloatTy, IntTy, PolyFnSig, Ty},
+};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+
+use if_chain::if_chain;
+
+use crate::utils::{snippet, span_lint_and_sugg};
+
+declare_clippy_lint! {
+ /// **What it does:** Checks for usage of unconstrained numeric literals which may cause default numeric fallback in type
+ /// inference.
+ ///
+ /// Default numeric fallback means that if numeric types have not yet been bound to concrete
+ /// types at the end of type inference, then integer type is bound to `i32`, and similarly
+ /// floating type is bound to `f64`.
+ ///
+ /// See [RFC0212](https://github.com/rust-lang/rfcs/blob/master/text/0212-restore-int-fallback.md) for more information about the fallback.
+ ///
+ /// **Why is this bad?** For those who are very careful about types, default numeric fallback
+ /// can be a pitfall that cause unexpected runtime behavior.
+ ///
+ /// **Known problems:** This lint can only be allowed at the function level or above.
+ ///
+ /// **Example:**
+ /// ```rust
+ /// let i = 10;
+ /// let f = 1.23;
+ /// ```
+ ///
+ /// Use instead:
+ /// ```rust
+ /// let i = 10i32;
+ /// let f = 1.23f64;
+ /// ```
+ pub DEFAULT_NUMERIC_FALLBACK,
+ restriction,
+ "usage of unconstrained numeric literals which may cause default numeric fallback."
+}
+
+declare_lint_pass!(DefaultNumericFallback => [DEFAULT_NUMERIC_FALLBACK]);
+
+impl LateLintPass<'_> for DefaultNumericFallback {
+ fn check_body(&mut self, cx: &LateContext<'tcx>, body: &'tcx Body<'_>) {
+ let mut visitor = NumericFallbackVisitor::new(cx);
+ visitor.visit_body(body);
+ }
+}
+
+struct NumericFallbackVisitor<'a, 'tcx> {
+ /// Stack manages type bound of exprs. The top element holds current expr type.
+ ty_bounds: Vec<TyBound<'tcx>>,
+
+ cx: &'a LateContext<'tcx>,
+}
+
+impl<'a, 'tcx> NumericFallbackVisitor<'a, 'tcx> {
+ fn new(cx: &'a LateContext<'tcx>) -> Self {
+ Self {
+ ty_bounds: vec![TyBound::Nothing],
+ cx,
+ }
+ }
+
+ /// Check whether a passed literal has potential to cause fallback or not.
+ fn check_lit(&self, lit: &Lit, lit_ty: Ty<'tcx>) {
+ if_chain! {
+ if let Some(ty_bound) = self.ty_bounds.last();
+ if matches!(lit.node,
+ LitKind::Int(_, LitIntType::Unsuffixed) | LitKind::Float(_, LitFloatType::Unsuffixed));
+ if !ty_bound.is_integral();
+ then {
+ let suffix = match lit_ty.kind() {
+ ty::Int(IntTy::I32) => "i32",
+ ty::Float(FloatTy::F64) => "f64",
+ // Default numeric fallback never results in other types.
+ _ => return,
+ };
+
+ let sugg = format!("{}_{}", snippet(self.cx, lit.span, ""), suffix);
+ span_lint_and_sugg(
+ self.cx,
+ DEFAULT_NUMERIC_FALLBACK,
+ lit.span,
+ "default numeric fallback might occur",
+ "consider adding suffix",
+ sugg,
+ Applicability::MaybeIncorrect,
+ );
+ }
+ }
+ }
+}
+
+impl<'a, 'tcx> Visitor<'tcx> for NumericFallbackVisitor<'a, 'tcx> {
+ type Map = Map<'tcx>;
+
+ #[allow(clippy::too_many_lines)]
+ fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
+ match &expr.kind {
+ ExprKind::Call(func, args) => {
+ if let Some(fn_sig) = fn_sig_opt(self.cx, func.hir_id) {
+ for (expr, bound) in args.iter().zip(fn_sig.skip_binder().inputs().iter()) {
+ // Push found arg type, then visit arg.
+ self.ty_bounds.push(TyBound::Ty(bound));
+ self.visit_expr(expr);
+ self.ty_bounds.pop();
+ }
+ return;
+ }
+ },
+
+ ExprKind::MethodCall(_, _, args, _) => {
+ if let Some(def_id) = self.cx.typeck_results().type_dependent_def_id(expr.hir_id) {
+ let fn_sig = self.cx.tcx.fn_sig(def_id).skip_binder();
+ for (expr, bound) in args.iter().zip(fn_sig.inputs().iter()) {
+ self.ty_bounds.push(TyBound::Ty(bound));
+ self.visit_expr(expr);
+ self.ty_bounds.pop();
+ }
+ return;
+ }
+ },
+
+ ExprKind::Struct(_, fields, base) => {
+ if_chain! {
+ let ty = self.cx.typeck_results().expr_ty(expr);
+ if let Some(adt_def) = ty.ty_adt_def();
+ if adt_def.is_struct();
+ if let Some(variant) = adt_def.variants.iter().next();
+ then {
+ let fields_def = &variant.fields;
+
+ // Push field type then visit each field expr.
+ for field in fields.iter() {
+ let bound =
+ fields_def
+ .iter()
+ .find_map(|f_def| {
+ if f_def.ident == field.ident
+ { Some(self.cx.tcx.type_of(f_def.did)) }
+ else { None }
+ });
+ self.ty_bounds.push(bound.into());
+ self.visit_expr(field.expr);
+ self.ty_bounds.pop();
+ }
+
+ // Visit base with no bound.
+ if let Some(base) = base {
+ self.ty_bounds.push(TyBound::Nothing);
+ self.visit_expr(base);
+ self.ty_bounds.pop();
+ }
+ return;
+ }
+ }
+ },
+
+ ExprKind::Lit(lit) => {
+ let ty = self.cx.typeck_results().expr_ty(expr);
+ self.check_lit(lit, ty);
+ return;
+ },
+
+ _ => {},
+ }
+
+ walk_expr(self, expr);
+ }
+
+ fn visit_stmt(&mut self, stmt: &'tcx Stmt<'_>) {
+ match stmt.kind {
+ StmtKind::Local(local) => {
+ if local.ty.is_some() {
+ self.ty_bounds.push(TyBound::Any)
+ } else {
+ self.ty_bounds.push(TyBound::Nothing)
+ }
+ },
+
+ _ => self.ty_bounds.push(TyBound::Nothing),
+ }
+
+ walk_stmt(self, stmt);
+ self.ty_bounds.pop();
+ }
+
+ fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
+ NestedVisitorMap::None
+ }
+}
+
+fn fn_sig_opt<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<PolyFnSig<'tcx>> {
+ let node_ty = cx.typeck_results().node_type_opt(hir_id)?;
+ // We can't use `TyS::fn_sig` because it automatically performs substs, this may result in FNs.
+ match node_ty.kind() {
+ ty::FnDef(def_id, _) => Some(cx.tcx.fn_sig(*def_id)),
+ ty::FnPtr(fn_sig) => Some(*fn_sig),
+ _ => None,
+ }
+}
+
+#[derive(Debug, Clone, Copy)]
+enum TyBound<'tcx> {
+ Any,
+ Ty(Ty<'tcx>),
+ Nothing,
+}
+
+impl<'tcx> TyBound<'tcx> {
+ fn is_integral(self) -> bool {
+ match self {
+ TyBound::Any => true,
+ TyBound::Ty(t) => t.is_integral(),
+ TyBound::Nothing => false,
+ }
+ }
+}
+
+impl<'tcx> From<Option<Ty<'tcx>>> for TyBound<'tcx> {
+ fn from(v: Option<Ty<'tcx>>) -> Self {
+ match v {
+ Some(t) => TyBound::Ty(t),
+ None => TyBound::Nothing,
+ }
+ }
+}
projects / rustc.git / blobdiff