identity_op lint fix for '&' with unsigned types
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@ -1,9 +1,9 @@
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use consts::{constant_simple, Constant};
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use rustc::lint::*;
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use rustc::hir::*;
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use rustc::lint::*;
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use rustc_const_math::ConstInt;
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use syntax::codemap::Span;
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use utils::{in_macro, snippet, span_lint};
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use syntax::attr::IntType::{SignedInt, UnsignedInt};
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/// **What it does:** Checks for identity operations, e.g. `x + 0`.
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///
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@ -58,15 +58,28 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for IdentityOp {
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}
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}
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fn no_zeros(v: &ConstInt) -> bool {
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match *v {
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ConstInt::I8(i) => i.count_zeros() == 0,
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ConstInt::I16(i) => i.count_zeros() == 0,
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ConstInt::I32(i) => i.count_zeros() == 0,
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ConstInt::I64(i) => i.count_zeros() == 0,
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ConstInt::I128(i) => i.count_zeros() == 0,
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ConstInt::U8(i) => i.count_zeros() == 0,
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ConstInt::U16(i) => i.count_zeros() == 0,
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ConstInt::U32(i) => i.count_zeros() == 0,
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ConstInt::U64(i) => i.count_zeros() == 0,
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ConstInt::U128(i) => i.count_zeros() == 0,
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_ => false
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}
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}
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#[allow(cast_possible_wrap)]
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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, e) {
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if match m {
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0 => v.to_u128_unchecked() == 0,
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-1 => match v.int_type() {
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SignedInt(_) => (v.to_u128_unchecked() as i128 == -1),
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UnsignedInt(_) => false,
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},
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-1 => no_zeros(&v),
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1 => v.to_u128_unchecked() == 1,
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_ => unreachable!(),
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} {
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@ -27,4 +27,7 @@ fn main() {
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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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let u : u8 = 0;
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u & 255;
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}
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@ -42,3 +42,9 @@ error: the operation is ineffective. Consider reducing it to `x`
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29 | -1 & x;
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| ^^^^^^
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error: the operation is ineffective. Consider reducing it to `u`
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--> $DIR/identity_op.rs:32:5
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32 | u & 255;
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| ^^^^^^^
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