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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
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@bors
bors committed Aug 26, 2020
2 parents 894581b + 2d85314 commit 64c4bb0
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Showing 2 changed files with 47 additions and 27 deletions.
30 changes: 14 additions & 16 deletions clippy_lints/src/float_equality_without_abs.rs
View file
Original file line number Diff line number Diff line change
@@ -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};
Expand Down Expand Up @@ -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,
);
}
);
}
}
Expand Down
44 changes: 33 additions & 11 deletions tests/ui/float_equality_without_abs.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -2,69 +2,91 @@ error: float equality check without `.abs()`
--> $DIR/float_equality_without_abs.rs:4:5
|
LL | (a - b) < f32::EPSILON
| ^^^^^^^^^^^^^^^^^^^^^^ help: add `.abs()`: `(a - b).abs()`
| -------^^^^^^^^^^^^^^^
| |
| help: add `.abs()`: `(a - b).abs()`
|
= note: `-D clippy::float-equality-without-abs` implied by `-D warnings`

error: float equality check without `.abs()`
--> $DIR/float_equality_without_abs.rs:13:13
|
LL | let _ = (a - b) < f32::EPSILON;
| ^^^^^^^^^^^^^^^^^^^^^^ help: add `.abs()`: `(a - b).abs()`
| -------^^^^^^^^^^^^^^^
| |
| help: add `.abs()`: `(a - b).abs()`

error: float equality check without `.abs()`
--> $DIR/float_equality_without_abs.rs:14:13
|
LL | let _ = a - b < f32::EPSILON;
| ^^^^^^^^^^^^^^^^^^^^ help: add `.abs()`: `(a - b).abs()`
| -----^^^^^^^^^^^^^^^
| |
| help: add `.abs()`: `(a - b).abs()`

error: float equality check without `.abs()`
--> $DIR/float_equality_without_abs.rs:15:13
|
LL | let _ = a - b.abs() < f32::EPSILON;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add `.abs()`: `(a - b.abs()).abs()`
| -----------^^^^^^^^^^^^^^^
| |
| help: add `.abs()`: `(a - b.abs()).abs()`

error: float equality check without `.abs()`
--> $DIR/float_equality_without_abs.rs:16:13
|
LL | let _ = (a as f64 - b as f64) < f64::EPSILON;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add `.abs()`: `(a as f64 - b as f64).abs()`
| ---------------------^^^^^^^^^^^^^^^
| |
| help: add `.abs()`: `(a as f64 - b as f64).abs()`

error: float equality check without `.abs()`
--> $DIR/float_equality_without_abs.rs:17:13
|
LL | let _ = 1.0 - 2.0 < f32::EPSILON;
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: add `.abs()`: `(1.0 - 2.0).abs()`
| ---------^^^^^^^^^^^^^^^
| |
| help: add `.abs()`: `(1.0 - 2.0).abs()`

error: float equality check without `.abs()`
--> $DIR/float_equality_without_abs.rs:19:13
|
LL | let _ = f32::EPSILON > (a - b);
| ^^^^^^^^^^^^^^^^^^^^^^ help: add `.abs()`: `(a - b).abs()`
| ^^^^^^^^^^^^^^^-------
| |
| help: add `.abs()`: `(a - b).abs()`

error: float equality check without `.abs()`
--> $DIR/float_equality_without_abs.rs:20:13
|
LL | let _ = f32::EPSILON > a - b;
| ^^^^^^^^^^^^^^^^^^^^ help: add `.abs()`: `(a - b).abs()`
| ^^^^^^^^^^^^^^^-----
| |
| help: add `.abs()`: `(a - b).abs()`

error: float equality check without `.abs()`
--> $DIR/float_equality_without_abs.rs:21:13
|
LL | let _ = f32::EPSILON > a - b.abs();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add `.abs()`: `(a - b.abs()).abs()`
| ^^^^^^^^^^^^^^^-----------
| |
| help: add `.abs()`: `(a - b.abs()).abs()`

error: float equality check without `.abs()`
--> $DIR/float_equality_without_abs.rs:22:13
|
LL | let _ = f64::EPSILON > (a as f64 - b as f64);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add `.abs()`: `(a as f64 - b as f64).abs()`
| ^^^^^^^^^^^^^^^---------------------
| |
| help: add `.abs()`: `(a as f64 - b as f64).abs()`

error: float equality check without `.abs()`
--> $DIR/float_equality_without_abs.rs:23:13
|
LL | let _ = f32::EPSILON > 1.0 - 2.0;
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: add `.abs()`: `(1.0 - 2.0).abs()`
| ^^^^^^^^^^^^^^^---------
| |
| help: add `.abs()`: `(1.0 - 2.0).abs()`

error: aborting due to 11 previous errors

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