float_cmp: Don't lint self comparisons.

Author: Jarcho

clippy_lints/src/operators/float_cmp.rs

@@ -2,9 +2,10 @@ use clippy_utils::consts::{constant, Constant};
 use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::sugg::Sugg;
 use clippy_utils::visitors::{for_each_expr, is_const_evaluatable};
-use clippy_utils::{get_item_name, is_expr_named_const, peel_hir_expr_while, SpanlessEq};
+use clippy_utils::{get_item_name, is_expr_named_const, path_res, peel_hir_expr_while, SpanlessEq};
 use core::ops::ControlFlow;
 use rustc_errors::Applicability;
+use rustc_hir::def::Res;
 use rustc_hir::{BinOpKind, BorrowKind, Expr, ExprKind, UnOp, Unsafety};
 use rustc_lint::LateContext;
 use rustc_middle::ty::{self, Ty, TypeFlags, TypeVisitableExt};
@@ -32,6 +33,10 @@ pub(crate) fn check<'tcx>(
         && !(matches!(left_red.kind, ExprKind::Lit(_)) && matches!(right_red.kind, ExprKind::Lit(_)))
         // Allow comparing the results of signum()
         && !(is_signum(cx, left_red) && is_signum(cx, right_red))
+        && match (path_res(cx, left_red), path_res(cx, right_red)) {
+            (Res::Err, _) | (_, Res::Err) => true,
+            (left, right) => left != right,
+        }
     {
         let left_c = constant(cx, cx.typeck_results(), left_red);
         let is_left_const = left_c.is_some();
@@ -64,7 +69,7 @@ pub(crate) fn check<'tcx>(
 
         if let Some(name) = get_item_name(cx, expr) {
             let name = name.as_str();
-            if name == "eq" || name == "ne" || name == "is_nan" || name.starts_with("eq_") || name.ends_with("_eq") {
+            if name == "eq" || name == "ne" || name.starts_with("eq_") || name.ends_with("_eq") {
                 return;
             }
         }

tests/ui-toml/float_cmp_change_detection/test.rs

@@ -1,6 +1,7 @@
 //@no-rustfix
 
 #![deny(clippy::float_cmp)]
+#![allow(clippy::op_ref, clippy::eq_op)]
 
 fn main() {
     {
@@ -26,4 +27,14 @@ fn main() {
             let _ = x == x + 1.0;
         }
     }
+    {
+        fn _f(x: f32) {
+            let _ = x == x;
+            let _ = x != x;
+            let _ = x == -x;
+            let _ = -x == x;
+            let _ = x as f64 == x as f64;
+            let _ = &&x == &&x;
+        }
+    }
 }

tests/ui-toml/float_cmp_change_detection/test.stderr

@@ -1,5 +1,5 @@
 error: strict comparison of `f32` or `f64`
-  --> $DIR/test.rs:25:21
+  --> $DIR/test.rs:26:21
    |
 LL |             let _ = x + 1.0 == x;
    |                     ^^^^^^^^^^^^ help: consider comparing them within some margin of error: `(x + 1.0 - x).abs() < error_margin`
@@ -11,7 +11,7 @@ LL | #![deny(clippy::float_cmp)]
    |         ^^^^^^^^^^^^^^^^^
 
 error: strict comparison of `f32` or `f64`
-  --> $DIR/test.rs:26:21
+  --> $DIR/test.rs:27:21
    |
 LL |             let _ = x == x + 1.0;
    |                     ^^^^^^^^^^^^ help: consider comparing them within some margin of error: `(x - (x + 1.0)).abs() < error_margin`

tests/ui-toml/float_cmp_constant_comparisons/test.rs

@@ -1,6 +1,7 @@
 //@no-rustfix
 
 #![deny(clippy::float_cmp)]
+#![allow(clippy::op_ref, clippy::eq_op)]
 
 fn main() {
     {
@@ -26,4 +27,14 @@ fn main() {
             let _ = x == x + 1.0;
         }
     }
+    {
+        fn _f(x: f32) {
+            let _ = x == x;
+            let _ = x != x;
+            let _ = x == -x;
+            let _ = -x == x;
+            let _ = x as f64 == x as f64;
+            let _ = &&x == &&x;
+        }
+    }
 }

tests/ui-toml/float_cmp_constant_comparisons/test.stderr

@@ -1,5 +1,5 @@
 error: strict comparison of `f32` or `f64`
-  --> $DIR/test.rs:16:17
+  --> $DIR/test.rs:17:17
    |
 LL |         let _ = f(1.0) == f(2.0);
    |                 ^^^^^^^^^^^^^^^^ help: consider comparing them within some margin of error: `(f(1.0) - f(2.0)).abs() < error_margin`

tests/ui-toml/float_cmp_named_constants/test.rs

@@ -1,6 +1,7 @@
 //@no-rustfix
 
 #![deny(clippy::float_cmp)]
+#![allow(clippy::op_ref, clippy::eq_op)]
 
 fn main() {
     {
@@ -26,4 +27,14 @@ fn main() {
             let _ = x == x + 1.0;
         }
     }
+    {
+        fn _f(x: f32) {
+            let _ = x == x;
+            let _ = x != x;
+            let _ = x == -x;
+            let _ = -x == x;
+            let _ = x as f64 == x as f64;
+            let _ = &&x == &&x;
+        }
+    }
 }

tests/ui-toml/float_cmp_named_constants/test.stderr

@@ -1,5 +1,5 @@
 error: strict comparison of `f32` or `f64`
-  --> $DIR/test.rs:9:21
+  --> $DIR/test.rs:10:21
    |
 LL |             let _ = x == C;
    |                     ^^^^^^ help: consider comparing them within some margin of error: `(x - C).abs() < error_margin`

tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr

@@ -202,6 +202,9 @@ error: error reading Clippy's configuration file: unknown field `allow_mixed_uni
            enum-variant-name-threshold
            enum-variant-size-threshold
            excessive-nesting-threshold
+           float-cmp-ignore-change-detection
+           float-cmp-ignore-constant-comparisons
+           float-cmp-ignore-named-constants
            future-size-threshold
            ignore-interior-mutability
            large-error-threshold

tests/ui/float_cmp.rs

@@ -1,7 +1,7 @@
 //@no-rustfix
 
 #![warn(clippy::float_cmp)]
-#![allow(clippy::op_ref)]
+#![allow(clippy::op_ref, clippy::eq_op)]
 
 fn main() {
     {
@@ -330,4 +330,16 @@ fn main() {
             //~^ ERROR: strict comparison of `f32` or `f64`
         }
     }
+
+    // Self comparisons
+    {
+        fn _f(x: f32) {
+            let _ = x == x;
+            let _ = x != x;
+            let _ = x == -x;
+            let _ = -x == x;
+            let _ = x as f64 == x as f64;
+            let _ = &&x == &&x;
+        }
+    }
 }