Rollup merge of #106093 - notriddle:notriddle/docblock-short-overflow, r=GuillaumeGomez

[rust.git] / compiler / rustc_lint_defs / src / builtin.rs

diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 848906e29d5b189172bb1e18ad67d266d196765a..67868ded0b86b5b4c9de2442bfc2a75515fee6a0 100644 (file)
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -1026,10 +1026,11 @@
     /// ### Example
     ///
     /// ```rust,compile_fail
+    /// #![feature(const_ptr_read)]
     /// const FOO: () = unsafe {
-    ///     let x = [0_u8; 10];
-    ///     let y = x.as_ptr() as *const u32;
-    ///     *y; // the address of a `u8` array is unknown and thus we don't know if
+    ///     let x = &[0_u8; 4];
+    ///     let y = x.as_ptr().cast::<u32>();
+    ///     y.read(); // the address of a `u8` array is unknown and thus we don't know if
     ///     // it is aligned enough for reading a `u32`.
     /// };
     /// ```
@@ -1404,7 +1405,7 @@
     /// struct S;
     ///
     /// impl S {
-    ///     fn late<'a, 'b>(self, _: &'a u8, _: &'b u8) {}
+    ///     fn late(self, _: &u8, _: &u8) {}
     /// }
     ///
     /// fn main() {
@@ -3310,6 +3311,7 @@
         FFI_UNWIND_CALLS,
         REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS,
         NAMED_ARGUMENTS_USED_POSITIONALLY,
+        IMPLIED_BOUNDS_ENTAILMENT,
     ]
 }
 
@@ -3997,3 +3999,44 @@
     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,
+    /// requires the main function to prove that 's: 'static, but the impl method is allowed
+    /// 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,
+    Warn,
+    "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::FutureReleaseError,
+    };
+}