Add IMPLIED_BOUNDS_ENTAILMENT lint

compiler/rustc_lint_defs/src/builtin.rs

@@ -3998,3 +3998,44 @@ declare_lint! {
     Warn,
     "named arguments in format used positionally"
 }
+
+declare_lint! {
+    /// The `implied_bounds_entailment` lint detects cases where the arguments of an impl method
+    /// have stronger implied bounds than those from the trait method it's implementing.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// #![deny(implied_bounds_entailment)]
+    ///
+    /// trait Trait {
+    ///     fn get<'s>(s: &'s str, _: &'static &'static ()) -> &'static str;
+    /// }
+    ///
+    /// impl Trait for () {
+    ///     fn get<'s>(s: &'s str, _: &'static &'s ()) -> &'static str {
+    ///         s
+    ///     }
+    /// }
+    ///
+    /// let val = <() as Trait>::get(&String::from("blah blah blah"), &&());
+    /// println!("{}", val);
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// Neither the trait method, which provides no implied bounds about `'s`, nor the impl,
+    /// which can't name `'s`, requires the main function to prove that 's: 'static, but the
+    /// impl method is able to assume that 's: 'static within its own body.
+    ///
+    /// This can be used to implement an unsound API if used incorrectly.
+    pub IMPLIED_BOUNDS_ENTAILMENT,
+    Deny,
+    "impl method assumes more implied bounds than its corresponding trait method",
+    @future_incompatible = FutureIncompatibleInfo {
+        reference: "issue #105572 <https://github.com/rust-lang/rust/issues/105572>",
+        reason: FutureIncompatibilityReason::FutureReleaseErrorReportNow,
+    };
+}