Deprecate float_cmp_const

Author: Jarcho

clippy_lints/src/declared_lints.rs

@@ -570,7 +570,6 @@ pub(crate) static LINTS: &[&crate::LintInfo] = &[
     crate::operators::ERASING_OP_INFO,
     crate::operators::FLOAT_ARITHMETIC_INFO,
     crate::operators::FLOAT_CMP_INFO,
-    crate::operators::FLOAT_CMP_CONST_INFO,
     crate::operators::FLOAT_EQUALITY_WITHOUT_ABS_INFO,
     crate::operators::IDENTITY_OP_INFO,
     crate::operators::IMPOSSIBLE_COMPARISONS_INFO,

clippy_lints/src/deprecated_lints.rs

@@ -241,3 +241,14 @@ declare_deprecated_lint! {
     pub MISMATCHED_TARGET_OS,
     "this lint has been replaced by `unexpected_cfgs`"
 }
+
+declare_deprecated_lint! {
+    /// ### What it does
+    /// Nothing. This lint has been deprecated.
+    ///
+    /// ### Deprecation reason
+    /// `float_cmp` handles this via config options
+    #[clippy::version = "1.76.0"]
+    pub FLOAT_CMP_CONST,
+    "`float_cmp` handles this via config options"
+}

clippy_lints/src/lib.deprecated.rs

@@ -75,4 +75,8 @@
         "clippy::mismatched_target_os",
         "this lint has been replaced by `unexpected_cfgs`",
     );
+    store.register_removed(
+        "clippy::float_cmp_const",
+        "`float_cmp` handles this via config options",
+    );
 }

clippy_lints/src/operators/mod.rs

@@ -633,70 +633,7 @@ declare_clippy_lint! {
 
 declare_clippy_lint! {
     /// ### What it does
-    /// Checks for (in-)equality comparisons on constant floating-point
-    /// values (apart from zero), except in functions called `*eq*` (which probably
-    /// implement equality for a type involving floats).
-    ///
-    /// ### Why restrict this?
-    /// Floating point calculations are usually imprecise, so asking if two values are *exactly*
-    /// equal is asking for trouble because arriving at the same logical result via different
-    /// routes (e.g. calculation versus constant) may yield different values.
-    ///
-    /// ### Example
-    ///
-    /// ```no_run
-    /// let a: f64 = 1000.1;
-    /// let b: f64 = 0.2;
-    /// let x = a + b;
-    /// const Y: f64 = 1000.3; // Expected value.
-    ///
-    /// // Actual value: 1000.3000000000001
-    /// println!("{x}");
-    ///
-    /// let are_equal = x == Y;
-    /// println!("{are_equal}"); // false
-    /// ```
-    ///
-    /// The correct way to compare floating point numbers is to define an allowed error margin. This
-    /// may be challenging if there is no "natural" error margin to permit. Broadly speaking, there
-    /// are two cases:
-    ///
-    /// 1. If your values are in a known range and you can define a threshold for "close enough to
-    ///    be equal", it may be appropriate to define an absolute error margin. For example, if your
-    ///    data is "length of vehicle in centimeters", you may consider 0.1 cm to be "close enough".
-    /// 1. If your code is more general and you do not know the range of values, you should use a
-    ///    relative error margin, accepting e.g. 0.1% of error regardless of specific values.
-    ///
-    /// For the scenario where you can define a meaningful absolute error margin, consider using:
-    ///
-    /// ```no_run
-    /// let a: f64 = 1000.1;
-    /// let b: f64 = 0.2;
-    /// let x = a + b;
-    /// const Y: f64 = 1000.3; // Expected value.
-    ///
-    /// const ALLOWED_ERROR_VEHICLE_LENGTH_CM: f64 = 0.1;
-    /// let within_tolerance = (x - Y).abs() < ALLOWED_ERROR_VEHICLE_LENGTH_CM;
-    /// println!("{within_tolerance}"); // true
-    /// ```
-    ///
-    /// NB! Do not use `f64::EPSILON` - while the error margin is often called "epsilon", this is
-    /// a different use of the term that is not suitable for floating point equality comparison.
-    /// Indeed, for the example above using `f64::EPSILON` as the allowed error would return `false`.
-    ///
-    /// For the scenario where no meaningful absolute error can be defined, refer to
-    /// [the floating point guide](https://www.floating-point-gui.de/errors/comparison)
-    /// for a reference implementation of relative error based comparison of floating point values.
-    /// `MIN_NORMAL` in the reference implementation is equivalent to `MIN_POSITIVE` in Rust.
-    #[clippy::version = "pre 1.29.0"]
-    pub FLOAT_CMP_CONST,
-    restriction,
-    "using `==` or `!=` on float constants instead of comparing difference with an allowed error"
-}
-
-declare_clippy_lint! {
-    /// ### What it does
-    /// Checks for getting the remainder of integer division by one or minus
+    /// Checks for getting the remainder of a division by one or minus
     /// one.
     ///
     /// ### Why is this bad?
@@ -884,7 +821,6 @@ impl_lint_pass!(Operators => [
     INTEGER_DIVISION,
     CMP_OWNED,
     FLOAT_CMP,
-    FLOAT_CMP_CONST,
     MODULO_ONE,
     MODULO_ARITHMETIC,
     NEEDLESS_BITWISE_BOOL,

tests/ui/deprecated.rs

@@ -20,5 +20,6 @@
 #![warn(clippy::wrong_pub_self_convention)]
 #![warn(clippy::maybe_misused_cfg)]
 #![warn(clippy::mismatched_target_os)]
+#![warn(clippy::float_cmp_const)]
 
 fn main() {}

tests/ui/deprecated.stderr

@@ -109,5 +109,11 @@ error: lint `clippy::mismatched_target_os` has been removed: this lint has been
 LL | #![warn(clippy::mismatched_target_os)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 18 previous errors
+error: lint `clippy::float_cmp_const` has been removed: `float_cmp` handles this via config options
+  --> tests/ui/deprecated.rs:23:9
+   |
+LL | #![warn(clippy::float_cmp_const)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 19 previous errors