Check if lhs < rhs in modulos and emit
This commit is contained in:
Tianyi Song
parent
0c483f69db
commit
a944ccb677
@ -5,7 +5,7 @@
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::source_map::Span;
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use clippy_utils::consts::{constant_simple, Constant};
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use clippy_utils::consts::{constant_full_int, constant_simple, Constant, FullInt};
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use clippy_utils::diagnostics::span_lint;
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use clippy_utils::{clip, unsext};
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@ -54,6 +54,7 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
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check(cx, left, -1, e.span, right.span);
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check(cx, right, -1, e.span, left.span);
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},
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BinOpKind::Rem => check_modulo(cx, left, right, e.span, left.span),
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_ => (),
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}
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}
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@ -70,6 +71,18 @@ fn is_allowed(cx: &LateContext<'_>, cmp: BinOp, left: &Expr<'_>, right: &Expr<'_
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&& constant_simple(cx, cx.typeck_results(), left) == Some(Constant::Int(1)))
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}
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fn check_modulo(cx: &LateContext<'_>, left: &Expr<'_>, right: &Expr<'_>, span: Span, arg: Span) {
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let lhs_const = constant_full_int(cx, cx.typeck_results(), left);
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let rhs_const = constant_full_int(cx, cx.typeck_results(), right);
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if match (lhs_const, rhs_const) {
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(Some(FullInt::S(lv)), Some(FullInt::S(rv))) => lv.abs() < rv,
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(Some(FullInt::U(lv)), Some(FullInt::U(rv))) => lv < rv,
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_ => return,
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} {
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span_ineffective_operation(cx, span, arg);
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}
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}
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fn check(cx: &LateContext<'_>, e: &Expr<'_>, m: i8, span: Span, arg: Span) {
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if let Some(Constant::Int(v)) = constant_simple(cx, cx.typeck_results(), e).map(Constant::peel_refs) {
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let check = match *cx.typeck_results().expr_ty(e).peel_refs().kind() {
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@ -83,15 +96,19 @@ fn check(cx: &LateContext<'_>, e: &Expr<'_>, m: i8, span: Span, arg: Span) {
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1 => v == 1,
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_ => unreachable!(),
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} {
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span_lint(
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cx,
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IDENTITY_OP,
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span,
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&format!(
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"the operation is ineffective. Consider reducing it to `{}`",
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snippet(cx, arg, "..")
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),
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);
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span_ineffective_operation(cx, span, arg);
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}
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}
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}
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fn span_ineffective_operation(cx: &LateContext<'_>, span: Span, arg: Span) {
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span_lint(
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cx,
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IDENTITY_OP,
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span,
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&format!(
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"the operation is ineffective. Consider reducing it to `{}`",
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snippet(cx, arg, "..")
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),
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);
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}
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@ -66,4 +66,10 @@ fn main() {
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let b = a << 0; // no error: non-integer
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1 * Meter; // no error: non-integer
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2 % 3;
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-2 % 3;
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x + 1 % 3;
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(x + 1) % 3; // no error
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4 % 3; // no error
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}
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@ -78,5 +78,23 @@ error: the operation is ineffective. Consider reducing it to `x`
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LL | x >> &0;
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| ^^^^^^^
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error: aborting due to 13 previous errors
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error: the operation is ineffective. Consider reducing it to `2`
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--> $DIR/identity_op.rs:70:5
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LL | 2 % 3;
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| ^^^^^
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error: the operation is ineffective. Consider reducing it to `-2`
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--> $DIR/identity_op.rs:71:5
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LL | -2 % 3;
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| ^^^^^^
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error: the operation is ineffective. Consider reducing it to `1`
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--> $DIR/identity_op.rs:72:9
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LL | x + 1 % 3;
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| ^^^^^
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error: aborting due to 16 previous errors
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@ -1,5 +1,10 @@
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#![warn(clippy::modulo_arithmetic)]
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#![allow(clippy::no_effect, clippy::unnecessary_operation, clippy::modulo_one)]
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#![allow(
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clippy::no_effect,
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clippy::unnecessary_operation,
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clippy::modulo_one,
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clippy::identity_op
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)]
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fn main() {
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// Lint when both sides are const and of the opposite sign
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@ -1,5 +1,5 @@
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error: you are using modulo operator on constants with different signs: `-1 % 2`
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--> $DIR/modulo_arithmetic_integral_const.rs:6:5
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--> $DIR/modulo_arithmetic_integral_const.rs:11:5
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LL | -1 % 2;
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| ^^^^^^
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@ -9,7 +9,7 @@ LL | -1 % 2;
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `1 % -2`
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--> $DIR/modulo_arithmetic_integral_const.rs:7:5
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--> $DIR/modulo_arithmetic_integral_const.rs:12:5
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LL | 1 % -2;
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| ^^^^^^
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@ -18,7 +18,7 @@ LL | 1 % -2;
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `-1 % 3`
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--> $DIR/modulo_arithmetic_integral_const.rs:8:5
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--> $DIR/modulo_arithmetic_integral_const.rs:13:5
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LL | (1 - 2) % (1 + 2);
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| ^^^^^^^^^^^^^^^^^
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@ -27,7 +27,7 @@ LL | (1 - 2) % (1 + 2);
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `3 % -1`
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--> $DIR/modulo_arithmetic_integral_const.rs:9:5
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--> $DIR/modulo_arithmetic_integral_const.rs:14:5
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LL | (1 + 2) % (1 - 2);
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| ^^^^^^^^^^^^^^^^^
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@ -36,7 +36,7 @@ LL | (1 + 2) % (1 - 2);
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `-35 % 300000`
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--> $DIR/modulo_arithmetic_integral_const.rs:10:5
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--> $DIR/modulo_arithmetic_integral_const.rs:15:5
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LL | 35 * (7 - 4 * 2) % (-500 * -600);
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -45,7 +45,7 @@ LL | 35 * (7 - 4 * 2) % (-500 * -600);
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `-1 % 2`
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--> $DIR/modulo_arithmetic_integral_const.rs:12:5
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--> $DIR/modulo_arithmetic_integral_const.rs:17:5
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LL | -1i8 % 2i8;
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| ^^^^^^^^^^
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@ -54,7 +54,7 @@ LL | -1i8 % 2i8;
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `1 % -2`
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--> $DIR/modulo_arithmetic_integral_const.rs:13:5
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--> $DIR/modulo_arithmetic_integral_const.rs:18:5
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LL | 1i8 % -2i8;
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| ^^^^^^^^^^
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@ -63,7 +63,7 @@ LL | 1i8 % -2i8;
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `-1 % 2`
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--> $DIR/modulo_arithmetic_integral_const.rs:14:5
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--> $DIR/modulo_arithmetic_integral_const.rs:19:5
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LL | -1i16 % 2i16;
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| ^^^^^^^^^^^^
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@ -72,7 +72,7 @@ LL | -1i16 % 2i16;
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `1 % -2`
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--> $DIR/modulo_arithmetic_integral_const.rs:15:5
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--> $DIR/modulo_arithmetic_integral_const.rs:20:5
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LL | 1i16 % -2i16;
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| ^^^^^^^^^^^^
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@ -81,7 +81,7 @@ LL | 1i16 % -2i16;
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `-1 % 2`
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--> $DIR/modulo_arithmetic_integral_const.rs:16:5
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--> $DIR/modulo_arithmetic_integral_const.rs:21:5
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LL | -1i32 % 2i32;
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| ^^^^^^^^^^^^
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@ -90,7 +90,7 @@ LL | -1i32 % 2i32;
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `1 % -2`
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--> $DIR/modulo_arithmetic_integral_const.rs:17:5
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--> $DIR/modulo_arithmetic_integral_const.rs:22:5
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LL | 1i32 % -2i32;
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| ^^^^^^^^^^^^
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@ -99,7 +99,7 @@ LL | 1i32 % -2i32;
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `-1 % 2`
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--> $DIR/modulo_arithmetic_integral_const.rs:18:5
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--> $DIR/modulo_arithmetic_integral_const.rs:23:5
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LL | -1i64 % 2i64;
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| ^^^^^^^^^^^^
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@ -108,7 +108,7 @@ LL | -1i64 % 2i64;
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `1 % -2`
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--> $DIR/modulo_arithmetic_integral_const.rs:19:5
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--> $DIR/modulo_arithmetic_integral_const.rs:24:5
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LL | 1i64 % -2i64;
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| ^^^^^^^^^^^^
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@ -117,7 +117,7 @@ LL | 1i64 % -2i64;
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `-1 % 2`
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--> $DIR/modulo_arithmetic_integral_const.rs:20:5
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--> $DIR/modulo_arithmetic_integral_const.rs:25:5
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LL | -1i128 % 2i128;
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| ^^^^^^^^^^^^^^
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@ -126,7 +126,7 @@ LL | -1i128 % 2i128;
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `1 % -2`
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--> $DIR/modulo_arithmetic_integral_const.rs:21:5
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--> $DIR/modulo_arithmetic_integral_const.rs:26:5
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LL | 1i128 % -2i128;
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| ^^^^^^^^^^^^^^
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@ -135,7 +135,7 @@ LL | 1i128 % -2i128;
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `-1 % 2`
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--> $DIR/modulo_arithmetic_integral_const.rs:22:5
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--> $DIR/modulo_arithmetic_integral_const.rs:27:5
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LL | -1isize % 2isize;
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| ^^^^^^^^^^^^^^^^
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@ -144,7 +144,7 @@ LL | -1isize % 2isize;
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= note: or consider using `rem_euclid` or similar function
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error: you are using modulo operator on constants with different signs: `1 % -2`
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--> $DIR/modulo_arithmetic_integral_const.rs:23:5
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--> $DIR/modulo_arithmetic_integral_const.rs:28:5
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LL | 1isize % -2isize;
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| ^^^^^^^^^^^^^^^^
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