Auto merge of #10618 - KisaragiEffective:patch-2, r=llogiq

[missing_const_for_fn] fix #7121

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changelog: [`missing_const_for_fn`] note about removing const may break compatibility

fix #7121

clippy_lints/src/missing_const_for_fn.rs

@@ -41,6 +41,7 @@
     /// can't be const as it calls a non-const function. Making `a` const and running Clippy again,
     /// will suggest to make `b` const, too.
     ///
+    /// If you are marking a public function with `const`, removing it again will break API compatibility.
     /// ### Example
     /// ```rust
     /// # struct Foo {