1 use clippy_utils
::diagnostics
::span_lint_and_sugg
;
2 use clippy_utils
::numeric_literal
;
3 use clippy_utils
::source
::snippet_opt
;
4 use if_chain
::if_chain
;
5 use rustc_ast
::ast
::{LitFloatType, LitIntType, LitKind}
;
6 use rustc_errors
::Applicability
;
8 intravisit
::{walk_expr, walk_stmt, Visitor}
,
9 Body
, Expr
, ExprKind
, HirId
, Lit
, Stmt
, StmtKind
,
11 use rustc_lint
::{LateContext, LateLintPass, LintContext}
;
13 lint
::in_external_macro
,
14 ty
::{self, FloatTy, IntTy, PolyFnSig, Ty}
,
16 use rustc_session
::{declare_lint_pass, declare_tool_lint}
;
19 declare_clippy_lint
! {
21 /// Checks for usage of unconstrained numeric literals which may cause default numeric fallback in type
24 /// Default numeric fallback means that if numeric types have not yet been bound to concrete
25 /// types at the end of type inference, then integer type is bound to `i32`, and similarly
26 /// floating type is bound to `f64`.
28 /// See [RFC0212](https://github.com/rust-lang/rfcs/blob/master/text/0212-restore-int-fallback.md) for more information about the fallback.
30 /// ### Why is this bad?
31 /// For those who are very careful about types, default numeric fallback
32 /// can be a pitfall that cause unexpected runtime behavior.
34 /// ### Known problems
35 /// This lint can only be allowed at the function level or above.
48 #[clippy::version = "1.52.0"]
49 pub DEFAULT_NUMERIC_FALLBACK
,
51 "usage of unconstrained numeric literals which may cause default numeric fallback."
54 declare_lint_pass
!(DefaultNumericFallback
=> [DEFAULT_NUMERIC_FALLBACK
]);
56 impl<'tcx
> LateLintPass
<'tcx
> for DefaultNumericFallback
{
57 fn check_body(&mut self, cx
: &LateContext
<'tcx
>, body
: &'tcx Body
<'_
>) {
58 let mut visitor
= NumericFallbackVisitor
::new(cx
);
59 visitor
.visit_body(body
);
63 struct NumericFallbackVisitor
<'a
, 'tcx
> {
64 /// Stack manages type bound of exprs. The top element holds current expr type.
65 ty_bounds
: Vec
<TyBound
<'tcx
>>,
67 cx
: &'a LateContext
<'tcx
>,
70 impl<'a
, 'tcx
> NumericFallbackVisitor
<'a
, 'tcx
> {
71 fn new(cx
: &'a LateContext
<'tcx
>) -> Self {
73 ty_bounds
: vec
![TyBound
::Nothing
],
78 /// Check whether a passed literal has potential to cause fallback or not.
79 fn check_lit(&self, lit
: &Lit
, lit_ty
: Ty
<'tcx
>) {
81 if !in_external_macro(self.cx
.sess(), lit
.span
);
82 if let Some(ty_bound
) = self.ty_bounds
.last();
84 LitKind
::Int(_
, LitIntType
::Unsuffixed
) | LitKind
::Float(_
, LitFloatType
::Unsuffixed
));
85 if !ty_bound
.is_numeric();
87 let (suffix
, is_float
) = match lit_ty
.kind() {
88 ty
::Int(IntTy
::I32
) => ("i32", false),
89 ty
::Float(FloatTy
::F64
) => ("f64", true),
90 // Default numeric fallback never results in other types.
94 let src
= if let Some(src
) = snippet_opt(self.cx
, lit
.span
) {
98 LitKind
::Int(src
, _
) => format
!("{}", src
),
99 LitKind
::Float(src
, _
) => format
!("{}", src
),
103 let sugg
= numeric_literal
::format(&src
, Some(suffix
), is_float
);
106 DEFAULT_NUMERIC_FALLBACK
,
108 "default numeric fallback might occur",
109 "consider adding suffix",
111 Applicability
::MaybeIncorrect
,
118 impl<'a
, 'tcx
> Visitor
<'tcx
> for NumericFallbackVisitor
<'a
, 'tcx
> {
119 #[allow(clippy::too_many_lines)]
120 fn visit_expr(&mut self, expr
: &'tcx Expr
<'_
>) {
122 ExprKind
::Call(func
, args
) => {
123 if let Some(fn_sig
) = fn_sig_opt(self.cx
, func
.hir_id
) {
124 for (expr
, bound
) in iter
::zip(*args
, fn_sig
.skip_binder().inputs()) {
125 // Push found arg type, then visit arg.
126 self.ty_bounds
.push(TyBound
::Ty(*bound
));
127 self.visit_expr(expr
);
128 self.ty_bounds
.pop();
134 ExprKind
::MethodCall(_
, args
, _
) => {
135 if let Some(def_id
) = self.cx
.typeck_results().type_dependent_def_id(expr
.hir_id
) {
136 let fn_sig
= self.cx
.tcx
.fn_sig(def_id
).skip_binder();
137 for (expr
, bound
) in iter
::zip(*args
, fn_sig
.inputs()) {
138 self.ty_bounds
.push(TyBound
::Ty(*bound
));
139 self.visit_expr(expr
);
140 self.ty_bounds
.pop();
146 ExprKind
::Struct(_
, fields
, base
) => {
147 let ty
= self.cx
.typeck_results().expr_ty(expr
);
149 if let Some(adt_def
) = ty
.ty_adt_def();
150 if adt_def
.is_struct();
151 if let Some(variant
) = adt_def
.variants
.iter().next();
153 let fields_def
= &variant
.fields
;
155 // Push field type then visit each field expr.
156 for field
in fields
.iter() {
161 if f_def
.ident(self.cx
.tcx
) == field
.ident
162 { Some(self.cx.tcx.type_of(f_def.did)) }
165 self.ty_bounds
.push(bound
.into());
166 self.visit_expr(field
.expr
);
167 self.ty_bounds
.pop();
170 // Visit base with no bound.
171 if let Some(base
) = base
{
172 self.ty_bounds
.push(TyBound
::Nothing
);
173 self.visit_expr(base
);
174 self.ty_bounds
.pop();
181 ExprKind
::Lit(lit
) => {
182 let ty
= self.cx
.typeck_results().expr_ty(expr
);
183 self.check_lit(lit
, ty
);
190 walk_expr(self, expr
);
193 fn visit_stmt(&mut self, stmt
: &'tcx Stmt
<'_
>) {
195 StmtKind
::Local(local
) => {
196 if local
.ty
.is_some() {
197 self.ty_bounds
.push(TyBound
::Any
);
199 self.ty_bounds
.push(TyBound
::Nothing
);
203 _
=> self.ty_bounds
.push(TyBound
::Nothing
),
206 walk_stmt(self, stmt
);
207 self.ty_bounds
.pop();
211 fn fn_sig_opt
<'tcx
>(cx
: &LateContext
<'tcx
>, hir_id
: HirId
) -> Option
<PolyFnSig
<'tcx
>> {
212 let node_ty
= cx
.typeck_results().node_type_opt(hir_id
)?
;
213 // We can't use `Ty::fn_sig` because it automatically performs substs, this may result in FNs.
214 match node_ty
.kind() {
215 ty
::FnDef(def_id
, _
) => Some(cx
.tcx
.fn_sig(*def_id
)),
216 ty
::FnPtr(fn_sig
) => Some(*fn_sig
),
221 #[derive(Debug, Clone, Copy)]
228 impl<'tcx
> TyBound
<'tcx
> {
229 fn is_numeric(self) -> bool
{
231 TyBound
::Any
=> true,
232 TyBound
::Ty(t
) => t
.is_numeric(),
233 TyBound
::Nothing
=> false,
238 impl<'tcx
> From
<Option
<Ty
<'tcx
>>> for TyBound
<'tcx
> {
239 fn from(v
: Option
<Ty
<'tcx
>>) -> Self {
241 Some(t
) => TyBound
::Ty(t
),
242 None
=> TyBound
::Nothing
,