mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-11 22:02:55 +00:00
c2b3f5c767
When `identity_op` identifies a `no_op`, provides a suggestion, it also checks the type of the type of the variable. If the variable is a reference that's been coerced into a value, e.g. ``` let x = &0i32; let _ = x + 0; ``` the suggestion will now use a derefence. This is done by identifying whether the variable is a reference to an integral value, and then whether it gets dereferenced. changelog: false positive: [`identity_op`]: corrected suggestion for reference coerced to value. fixes: #12050
214 lines
5.7 KiB
Rust
214 lines
5.7 KiB
Rust
#![warn(clippy::identity_op)]
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#![allow(unused)]
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#![allow(
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clippy::eq_op,
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clippy::no_effect,
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clippy::unnecessary_operation,
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clippy::op_ref,
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clippy::double_parens,
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clippy::uninlined_format_args,
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clippy::borrow_deref_ref,
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clippy::deref_addrof
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)]
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use std::fmt::Write as _;
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const ONE: i64 = 1;
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const NEG_ONE: i64 = -1;
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const ZERO: i64 = 0;
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struct A(String);
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impl std::ops::Shl<i32> for A {
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type Output = A;
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fn shl(mut self, other: i32) -> Self {
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let _ = write!(self.0, "{}", other);
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self
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}
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}
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struct Length(u8);
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struct Meter;
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impl core::ops::Mul<Meter> for u8 {
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type Output = Length;
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fn mul(self, _: Meter) -> Length {
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Length(self)
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}
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}
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#[rustfmt::skip]
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fn main() {
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let x = 0;
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x + 0;
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//~^ ERROR: this operation has no effect
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x + (1 - 1);
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//~^ ERROR: this operation has no effect
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x + 1;
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0 + x;
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//~^ ERROR: this operation has no effect
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1 + x;
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x - ZERO; //no error, as we skip lookups (for now)
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x | (0);
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//~^ ERROR: this operation has no effect
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((ZERO)) | x; //no error, as we skip lookups (for now)
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x * 1;
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//~^ ERROR: this operation has no effect
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1 * x;
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//~^ ERROR: this operation has no effect
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x / ONE; //no error, as we skip lookups (for now)
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x / 2; //no false positive
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x & NEG_ONE; //no error, as we skip lookups (for now)
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-1 & x;
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//~^ ERROR: this operation has no effect
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let u: u8 = 0;
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u & 255;
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//~^ ERROR: this operation has no effect
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1 << 0; // no error, this case is allowed, see issue 3430
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42 << 0;
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//~^ ERROR: this operation has no effect
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1 >> 0;
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//~^ ERROR: this operation has no effect
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42 >> 0;
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//~^ ERROR: this operation has no effect
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&x >> 0;
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//~^ ERROR: this operation has no effect
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x >> &0;
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//~^ ERROR: this operation has no effect
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let mut a = A(String::new());
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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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//~^ ERROR: this operation has no effect
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-2 % 3;
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//~^ ERROR: this operation has no effect
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2 % -3 + x;
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//~^ ERROR: this operation has no effect
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-2 % -3 + x;
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//~^ ERROR: this operation has no effect
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x + 1 % 3;
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//~^ ERROR: this operation has no effect
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(x + 1) % 3; // no error
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4 % 3; // no error
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4 % -3; // no error
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// See #8724
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let a = 0;
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let b = true;
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0 + if b { 1 } else { 2 };
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//~^ ERROR: this operation has no effect
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0 + if b { 1 } else { 2 } + if b { 3 } else { 4 };
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//~^ ERROR: this operation has no effect
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0 + match a { 0 => 10, _ => 20 };
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//~^ ERROR: this operation has no effect
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0 + match a { 0 => 10, _ => 20 } + match a { 0 => 30, _ => 40 };
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//~^ ERROR: this operation has no effect
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0 + if b { 1 } else { 2 } + match a { 0 => 30, _ => 40 };
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//~^ ERROR: this operation has no effect
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0 + match a { 0 => 10, _ => 20 } + if b { 3 } else { 4 };
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//~^ ERROR: this operation has no effect
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(if b { 1 } else { 2 }) + 0;
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//~^ ERROR: this operation has no effect
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0 + { a } + 3;
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//~^ ERROR: this operation has no effect
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0 + { a } * 2;
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//~^ ERROR: this operation has no effect
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0 + loop { let mut c = 0; if c == 10 { break c; } c += 1; } + { a * 2 };
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//~^ ERROR: this operation has no effect
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fn f(_: i32) {
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todo!();
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}
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f(1 * a + { 8 * 5 });
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//~^ ERROR: this operation has no effect
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f(0 + if b { 1 } else { 2 } + 3);
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//~^ ERROR: this operation has no effect
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const _: i32 = { 2 * 4 } + 0 + 3;
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//~^ ERROR: this operation has no effect
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const _: i32 = 0 + { 1 + 2 * 3 } + 3;
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//~^ ERROR: this operation has no effect
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0 + a as usize;
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//~^ ERROR: this operation has no effect
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let _ = 0 + a as usize;
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//~^ ERROR: this operation has no effect
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0 + { a } as usize;
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//~^ ERROR: this operation has no effect
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2 * (0 + { a });
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//~^ ERROR: this operation has no effect
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1 * ({ a } + 4);
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//~^ ERROR: this operation has no effect
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1 * 1;
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//~^ ERROR: this operation has no effect
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// Issue #9904
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let x = 0i32;
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let _: i32 = &x + 0;
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//~^ ERROR: this operation has no effect
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}
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pub fn decide(a: bool, b: bool) -> u32 {
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0 + if a { 1 } else { 2 } + if b { 3 } else { 5 }
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}
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/// The following tests are from / for issue #12050
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/// In short, the lint didn't work for coerced references,
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/// e.g. let x = &0; let y = x + 0;
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/// because the suggested fix was `let y = x;` but
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/// it should have been `let y = *x;`
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fn issue_12050() {
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{
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let x = &0i32;
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let _: i32 = *x + 0;
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//~^ ERROR: this operation has no effect
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let _: i32 = x + 0;
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//~^ ERROR: this operation has no effect
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}
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{
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let x = &&0i32;
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let _: i32 = **x + 0;
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//~^ ERROR: this operation has no effect
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let x = &&0i32;
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let _: i32 = *x + 0;
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//~^ ERROR: this operation has no effect
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}
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{
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// this is just silly
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let x = &&&0i32;
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let _: i32 = ***x + 0;
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//~^ ERROR: this operation has no effect
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let _: i32 = **x + 0;
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//~^ ERROR: this operation has no effect
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let x = 0i32;
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let _: i32 = *&x + 0;
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//~^ ERROR: this operation has no effect
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let _: i32 = **&&x + 0;
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//~^ ERROR: this operation has no effect
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let _: i32 = *&*&x + 0;
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//~^ ERROR: this operation has no effect
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let _: i32 = **&&*&x + 0;
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//~^ ERROR: this operation has no effect
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}
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{
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// this is getting ridiculous, but we should still see the same
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// error message so let's just keep going
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let x = &0i32;
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let _: i32 = **&&*&x + 0;
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//~^ ERROR: this operation has no effect
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let _: i32 = **&&*&x + 0;
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//~^ ERROR: this operation has no effect
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}
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}
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