Auto merge of #9148 - arieluy:then_some_unwrap_or, r=Jarcho

[rust.git] / clippy_lints / src / as_conversions.rs

diff --git a/clippy_lints/src/as_conversions.rs b/clippy_lints/src/as_conversions.rs
index 1ec3377193ec9b616d1a027b56e8e9978c23c85b..6e5c8f445818ebfb54bb5c45bbbe87b9a57b9cf9 100644 (file)
--- a/clippy_lints/src/as_conversions.rs
+++ b/clippy_lints/src/as_conversions.rs
@@ -1,36 +1,43 @@
-use rustc::lint::in_external_macro;
+use clippy_utils::diagnostics::span_lint_and_help;
 use rustc_ast::ast::{Expr, ExprKind};
 use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
-use crate::utils::span_lint_and_help;
-
 declare_clippy_lint! {
-    /// **What it does:** Checks for usage of `as` conversions.
+    /// ### What it does
+    /// Checks for usage of `as` conversions.
+    ///
+    /// Note that this lint is specialized in linting *every single* use of `as`
+    /// regardless of whether good alternatives exist or not.
+    /// If you want more precise lints for `as`, please consider using these separate lints:
+    /// `unnecessary_cast`, `cast_lossless/possible_truncation/possible_wrap/precision_loss/sign_loss`,
+    /// `fn_to_numeric_cast(_with_truncation)`, `char_lit_as_u8`, `ref_to_mut` and `ptr_as_ptr`.
+    /// There is a good explanation the reason why this lint should work in this way and how it is useful
+    /// [in this issue](https://github.com/rust-lang/rust-clippy/issues/5122).
     ///
-    /// **Why is this bad?** `as` conversions will perform many kinds of
+    /// ### Why is this bad?
+    /// `as` conversions will perform many kinds of
     /// conversions, including silently lossy conversions and dangerous coercions.
     /// There are cases when it makes sense to use `as`, so the lint is
     /// Allow by default.
     ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
+    /// ### Example
     /// ```rust,ignore
     /// let a: u32;
     /// ...
     /// f(a as u16);
     /// ```
     ///
-    /// Usually better represents the semantics you expect:
+    /// Use instead:
     /// ```rust,ignore
     /// f(a.try_into()?);
-    /// ```
-    /// or
-    /// ```rust,ignore
+    ///
+    /// // or
+    ///
     /// f(a.try_into().expect("Unexpected u16 overflow in f"));
     /// ```
-    ///
+    #[clippy::version = "1.41.0"]
     pub AS_CONVERSIONS,
     restriction,
     "using a potentially dangerous silent `as` conversion"
@@ -50,6 +57,7 @@ fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
                 AS_CONVERSIONS,
                 expr.span,
                 "using a potentially dangerous silent `as` conversion",
+                None,
                 "consider using a safe wrapper for this conversion",
             );
         }