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use clippy_utils::consts::{constant, Constant};
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::get_item_name;
use clippy_utils::sugg::Sugg;
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::{BinOpKind, Expr, ExprKind, UnOp};
use rustc_lint::LateContext;
use rustc_middle::ty;
use super::{FLOAT_CMP, FLOAT_CMP_CONST};
pub(crate) fn check<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx Expr<'_>,
op: BinOpKind,
left: &'tcx Expr<'_>,
right: &'tcx Expr<'_>,
) {
if (op == BinOpKind::Eq || op == BinOpKind::Ne) && (is_float(cx, left) || is_float(cx, right)) {
if is_allowed(cx, left) || is_allowed(cx, right) {
return;
}
// Allow comparing the results of signum()
if is_signum(cx, left) && is_signum(cx, right) {
return;
}
if let Some(name) = get_item_name(cx, expr) {
let name = name.as_str();
if name == "eq" || name == "ne" || name == "is_nan" || name.starts_with("eq_") || name.ends_with("_eq") {
return;
}
}
let is_comparing_arrays = is_array(cx, left) || is_array(cx, right);
let (lint, msg) = get_lint_and_message(
is_named_constant(cx, left) || is_named_constant(cx, right),
is_comparing_arrays,
);
span_lint_and_then(cx, lint, expr.span, msg, |diag| {
let lhs = Sugg::hir(cx, left, "..");
let rhs = Sugg::hir(cx, right, "..");
if !is_comparing_arrays {
diag.span_suggestion(
expr.span,
"consider comparing them within some margin of error",
format!(
"({}).abs() {} error_margin",
lhs - rhs,
if op == BinOpKind::Eq { '<' } else { '>' }
),
Applicability::HasPlaceholders, // snippet
);
}
diag.note("`f32::EPSILON` and `f64::EPSILON` are available for the `error_margin`");
});
}
}
fn get_lint_and_message(
is_comparing_constants: bool,
is_comparing_arrays: bool,
) -> (&'static rustc_lint::Lint, &'static str) {
if is_comparing_constants {
(
FLOAT_CMP_CONST,
if is_comparing_arrays {
"strict comparison of `f32` or `f64` constant arrays"
} else {
"strict comparison of `f32` or `f64` constant"
},
)
} else {
(
FLOAT_CMP,
if is_comparing_arrays {
"strict comparison of `f32` or `f64` arrays"
} else {
"strict comparison of `f32` or `f64`"
},
)
}
}
fn is_named_constant<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> bool {
if let Some((_, res)) = constant(cx, cx.typeck_results(), expr) {
res
} else {
false
}
}
fn is_allowed<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> bool {
match constant(cx, cx.typeck_results(), expr) {
Some((Constant::F32(f), _)) => f == 0.0 || f.is_infinite(),
Some((Constant::F64(f), _)) => f == 0.0 || f.is_infinite(),
Some((Constant::Vec(vec), _)) => vec.iter().all(|f| match f {
Constant::F32(f) => *f == 0.0 || (*f).is_infinite(),
Constant::F64(f) => *f == 0.0 || (*f).is_infinite(),
_ => false,
}),
_ => false,
}
}
// Return true if `expr` is the result of `signum()` invoked on a float value.
fn is_signum(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
// The negation of a signum is still a signum
if let ExprKind::Unary(UnOp::Neg, child_expr) = expr.kind {
return is_signum(cx, child_expr);
}
if_chain! {
if let ExprKind::MethodCall(method_name, self_arg, ..) = expr.kind;
if sym!(signum) == method_name.ident.name;
// Check that the receiver of the signum() is a float (expressions[0] is the receiver of
// the method call)
then {
return is_float(cx, self_arg);
}
}
false
}
fn is_float(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
let value = &cx.typeck_results().expr_ty(expr).peel_refs().kind();
if let ty::Array(arr_ty, _) = value {
return matches!(arr_ty.kind(), ty::Float(_));
};
matches!(value, ty::Float(_))
}
fn is_array(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
matches!(&cx.typeck_results().expr_ty(expr).peel_refs().kind(), ty::Array(_, _))
}
|
