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Auto merge of #5966 - 1c3t3a:1c3t3a-dev-5819-fix, r=Manishearth

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Corrects the float_equality_without_abs lint

Fixes an issue in the `float_equality_without_abs` lint. The lint suggestion was configured in a way that it lints the whole error and not just the subtraction part. In the current configuration the lint would suggest to change the expression in a wrong way, e.g.
```rust
let _ = (a - b) < f32::EPSILON; // before
let _ = (a - b).abs(); // after
```
This was dicovered by @flip1995. (See discussion of PR #5952).

Also the suggestion is now formatted via `utils::sugg`.
changelog: none
This commit is contained in:
bors 2020-08-26 18:15:42 +00:00
commit 64c4bb0d2b
2 changed files with 47 additions and 27 deletions
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30
clippy_lints/src/float_equality_without_abs.rs
View file

@ -1,5 +1,6 @@
use crate::utils::{match_qpath, paths, snippet, span_lint_and_sugg};
use crate::utils::{match_qpath, paths, span_lint_and_then, sugg};
use if_chain::if_chain;
use rustc_ast::util::parser::AssocOp;
use rustc_errors::Applicability;
use rustc_hir::{BinOpKind, Expr, ExprKind};
use rustc_lint::{LateContext, LateLintPass};
@ -84,27 +85,24 @@ impl<'tcx> LateLintPass<'tcx> for FloatEqualityWithoutAbs {
if let ty::Float(_) = t_val_r.kind;
then {
// get the snippet string
let lhs_string = snippet(
cx,
lhs.span,
"(...)",
);
let sug_l = sugg::Sugg::hir(cx, &val_l, "..");
let sug_r = sugg::Sugg::hir(cx, &val_r, "..");
// format the suggestion
let suggestion = if lhs_string.starts_with('(') {
format!("{}.abs()", lhs_string)
} else {
format!("({}).abs()", lhs_string)
};
let suggestion = format!("{}.abs()", sugg::make_assoc(AssocOp::Subtract, &sug_l, &sug_r).maybe_par());
// spans the lint
span_lint_and_sugg(
span_lint_and_then(
cx,
FLOAT_EQUALITY_WITHOUT_ABS,
expr.span,
"float equality check without `.abs()`",
"add `.abs()`",
suggestion,
Applicability::MaybeIncorrect,
| diag | {
diag.span_suggestion(
lhs.span,
"add `.abs()`",
suggestion,
Applicability::MaybeIncorrect,
);
}
);
}
}