rust/clippy_lints/src/legacy_numeric_constants.rs

286 lines
11 KiB
Rust

use clippy_config::msrvs::{Msrv, NUMERIC_ASSOCIATED_CONSTANTS};
use clippy_utils::diagnostics::{span_lint_and_then, span_lint_hir_and_then};
use clippy_utils::{get_parent_expr, is_from_proc_macro};
use hir::def_id::DefId;
use rustc_errors::{Applicability, SuggestionStyle};
use rustc_hir as hir;
use rustc_hir::{ExprKind, Item, ItemKind, QPath, UseKind};
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::lint::in_external_macro;
use rustc_session::impl_lint_pass;
use rustc_span::symbol::kw;
use rustc_span::{sym, Symbol};
declare_clippy_lint! {
/// ### What it does
/// Checks for usage of `<integer>::max_value()`, `std::<integer>::MAX`,
/// `std::<float>::EPSILON`, etc.
///
/// ### Why is this bad?
/// All of these have been superseded by the associated constants on their respective types,
/// such as `i128::MAX`. These legacy items may be deprecated in a future version of rust.
///
/// ### Example
/// ```rust
/// let eps = std::f32::EPSILON;
/// ```
/// Use instead:
/// ```rust
/// let eps = f32::EPSILON;
/// ```
#[clippy::version = "1.79.0"]
pub LEGACY_NUMERIC_CONSTANTS,
style,
"checks for usage of legacy std numeric constants and methods"
}
pub struct LegacyNumericConstants {
msrv: Msrv,
}
impl LegacyNumericConstants {
#[must_use]
pub fn new(msrv: Msrv) -> Self {
Self { msrv }
}
}
impl_lint_pass!(LegacyNumericConstants => [LEGACY_NUMERIC_CONSTANTS]);
impl<'tcx> LateLintPass<'tcx> for LegacyNumericConstants {
fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
// Integer modules are "TBD" deprecated, and the contents are too,
// so lint on the `use` statement directly.
if let ItemKind::Use(path, kind @ (UseKind::Single | UseKind::Glob)) = item.kind
&& self.msrv.meets(NUMERIC_ASSOCIATED_CONSTANTS)
&& !in_external_macro(cx.sess(), item.span)
&& let Some(def_id) = path.res[0].opt_def_id()
{
let module = if is_integer_module(cx, def_id) {
true
} else if is_numeric_const(cx, def_id) {
false
} else {
return;
};
span_lint_and_then(
cx,
LEGACY_NUMERIC_CONSTANTS,
path.span,
if module {
"importing legacy numeric constants"
} else {
"importing a legacy numeric constant"
},
|diag| {
if item.ident.name == kw::Underscore {
diag.help("remove this import");
return;
}
let def_path = cx.get_def_path(def_id);
if module && let [.., module_name] = &*def_path {
if kind == UseKind::Glob {
diag.help(format!("remove this import and use associated constants `{module_name}::<CONST>` from the primitive type instead"));
} else {
diag.help("remove this import").note(format!(
"then `{module_name}::<CONST>` will resolve to the respective associated constant"
));
}
} else if let [.., module_name, name] = &*def_path {
diag.help(
format!("remove this import and use the associated constant `{module_name}::{name}` from the primitive type instead")
);
}
},
);
}
}
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx rustc_hir::Expr<'tcx>) {
let ExprKind::Path(qpath) = &expr.kind else {
return;
};
// `std::<integer>::<CONST>` check
let (span, sugg, msg) = if let QPath::Resolved(None, path) = qpath
&& let Some(def_id) = path.res.opt_def_id()
&& is_numeric_const(cx, def_id)
&& let def_path = cx.get_def_path(def_id)
&& let [.., mod_name, name] = &*def_path
// Skip linting if this usage looks identical to the associated constant,
// since this would only require removing a `use` import (which is already linted).
&& !is_numeric_const_path_canonical(path, [*mod_name, *name])
{
(
expr.span,
format!("{mod_name}::{name}"),
"usage of a legacy numeric constant",
)
// `<integer>::xxx_value` check
} else if let QPath::TypeRelative(_, last_segment) = qpath
&& let Some(def_id) = cx.qpath_res(qpath, expr.hir_id).opt_def_id()
&& let Some(par_expr) = get_parent_expr(cx, expr)
&& let ExprKind::Call(_, []) = par_expr.kind
&& is_integer_method(cx, def_id)
{
let name = last_segment.ident.name.as_str();
(
last_segment.ident.span.with_hi(par_expr.span.hi()),
name[..=2].to_ascii_uppercase(),
"usage of a legacy numeric method",
)
} else {
return;
};
if self.msrv.meets(NUMERIC_ASSOCIATED_CONSTANTS)
&& !in_external_macro(cx.sess(), expr.span)
&& !is_from_proc_macro(cx, expr)
{
span_lint_hir_and_then(cx, LEGACY_NUMERIC_CONSTANTS, expr.hir_id, span, msg, |diag| {
diag.span_suggestion_with_style(
span,
"use the associated constant instead",
sugg,
Applicability::MaybeIncorrect,
SuggestionStyle::ShowAlways,
);
});
}
}
extract_msrv_attr!(LateContext);
}
fn is_integer_module(cx: &LateContext<'_>, did: DefId) -> bool {
matches!(
cx.tcx.get_diagnostic_name(did),
Some(
sym::isize_legacy_mod
| sym::i128_legacy_mod
| sym::i64_legacy_mod
| sym::i32_legacy_mod
| sym::i16_legacy_mod
| sym::i8_legacy_mod
| sym::usize_legacy_mod
| sym::u128_legacy_mod
| sym::u64_legacy_mod
| sym::u32_legacy_mod
| sym::u16_legacy_mod
| sym::u8_legacy_mod
)
)
}
fn is_numeric_const(cx: &LateContext<'_>, did: DefId) -> bool {
matches!(
cx.tcx.get_diagnostic_name(did),
Some(
sym::isize_legacy_const_max
| sym::isize_legacy_const_min
| sym::i128_legacy_const_max
| sym::i128_legacy_const_min
| sym::i16_legacy_const_max
| sym::i16_legacy_const_min
| sym::i32_legacy_const_max
| sym::i32_legacy_const_min
| sym::i64_legacy_const_max
| sym::i64_legacy_const_min
| sym::i8_legacy_const_max
| sym::i8_legacy_const_min
| sym::usize_legacy_const_max
| sym::usize_legacy_const_min
| sym::u128_legacy_const_max
| sym::u128_legacy_const_min
| sym::u16_legacy_const_max
| sym::u16_legacy_const_min
| sym::u32_legacy_const_max
| sym::u32_legacy_const_min
| sym::u64_legacy_const_max
| sym::u64_legacy_const_min
| sym::u8_legacy_const_max
| sym::u8_legacy_const_min
| sym::f32_legacy_const_digits
| sym::f32_legacy_const_epsilon
| sym::f32_legacy_const_infinity
| sym::f32_legacy_const_mantissa_dig
| sym::f32_legacy_const_max
| sym::f32_legacy_const_max_10_exp
| sym::f32_legacy_const_max_exp
| sym::f32_legacy_const_min
| sym::f32_legacy_const_min_10_exp
| sym::f32_legacy_const_min_exp
| sym::f32_legacy_const_min_positive
| sym::f32_legacy_const_nan
| sym::f32_legacy_const_neg_infinity
| sym::f32_legacy_const_radix
| sym::f64_legacy_const_digits
| sym::f64_legacy_const_epsilon
| sym::f64_legacy_const_infinity
| sym::f64_legacy_const_mantissa_dig
| sym::f64_legacy_const_max
| sym::f64_legacy_const_max_10_exp
| sym::f64_legacy_const_max_exp
| sym::f64_legacy_const_min
| sym::f64_legacy_const_min_10_exp
| sym::f64_legacy_const_min_exp
| sym::f64_legacy_const_min_positive
| sym::f64_legacy_const_nan
| sym::f64_legacy_const_neg_infinity
| sym::f64_legacy_const_radix
)
)
}
// Whether path expression looks like `i32::MAX`
fn is_numeric_const_path_canonical(expr_path: &hir::Path<'_>, [mod_name, name]: [Symbol; 2]) -> bool {
let [
hir::PathSegment {
ident: one, args: None, ..
},
hir::PathSegment {
ident: two, args: None, ..
},
] = expr_path.segments
else {
return false;
};
one.name == mod_name && two.name == name
}
fn is_integer_method(cx: &LateContext<'_>, did: DefId) -> bool {
matches!(
cx.tcx.get_diagnostic_name(did),
Some(
sym::isize_legacy_fn_max_value
| sym::isize_legacy_fn_min_value
| sym::i128_legacy_fn_max_value
| sym::i128_legacy_fn_min_value
| sym::i16_legacy_fn_max_value
| sym::i16_legacy_fn_min_value
| sym::i32_legacy_fn_max_value
| sym::i32_legacy_fn_min_value
| sym::i64_legacy_fn_max_value
| sym::i64_legacy_fn_min_value
| sym::i8_legacy_fn_max_value
| sym::i8_legacy_fn_min_value
| sym::usize_legacy_fn_max_value
| sym::usize_legacy_fn_min_value
| sym::u128_legacy_fn_max_value
| sym::u128_legacy_fn_min_value
| sym::u16_legacy_fn_max_value
| sym::u16_legacy_fn_min_value
| sym::u32_legacy_fn_max_value
| sym::u32_legacy_fn_min_value
| sym::u64_legacy_fn_max_value
| sym::u64_legacy_fn_min_value
| sym::u8_legacy_fn_max_value
| sym::u8_legacy_fn_min_value
)
)
}