Add migration lint for 2024 prelude additions

This adds the migration lint for the newly ambiguous methods `poll` and
`into_future`. When these methods are used on types implementing the
respective traits, it will be ambiguous in the future, which can lead to
hard errors or behavior changes depending on the exact circumstances.

compiler/rustc_lint_defs/src/builtin.rs

@@ -91,6 +91,7 @@ declare_lint_pass! {
         RUST_2021_PREFIXES_INCOMPATIBLE_SYNTAX,
         RUST_2021_PRELUDE_COLLISIONS,
         RUST_2024_INCOMPATIBLE_PAT,
+        RUST_2024_PRELUDE_COLLISIONS,
         SELF_CONSTRUCTOR_FROM_OUTER_ITEM,
         SEMICOLON_IN_EXPRESSIONS_FROM_MACROS,
         SINGLE_USE_LIFETIMES,
@@ -3750,6 +3751,46 @@ declare_lint! {
     };
 }
 
+declare_lint! {
+    /// The `rust_2024_prelude_collisions` lint detects the usage of trait methods which are ambiguous
+    /// with traits added to the prelude in future editions.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,edition2021,compile_fail
+    /// #![deny(rust_2024_prelude_collisions)]
+    /// trait Meow {
+    ///     fn poll(&self) {}
+    /// }
+    /// impl<T> Meow for T {}
+    ///
+    /// fn main() {
+    ///     core::pin::pin!(async {}).poll();
+    ///     //                        ^^^^^^
+    ///     // This call to try_into matches both Future::poll and Meow::poll as
+    ///     // `Future` has been added to the Rust prelude in 2024 edition.
+    /// }
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// Rust 2024, introduces two new additions to the standard library's prelude:
+    /// `Future` and `IntoFuture`. This results in an ambiguity as to which method/function
+    /// to call when an existing `poll`/`into_future` method is called via dot-call syntax or
+    /// a `poll`/`into_future` associated function is called directly on a type.
+    ///
+    pub RUST_2024_PRELUDE_COLLISIONS,
+    Allow,
+    "detects the usage of trait methods which are ambiguous with traits added to the \
+        prelude in future editions",
+    @future_incompatible = FutureIncompatibleInfo {
+        reason: FutureIncompatibilityReason::EditionError(Edition::Edition2024),
+        reference: "<https://doc.rust-lang.org/nightly/edition-guide/rust-2024/prelude.html>",
+    };
+}
+
 declare_lint! {
     /// The `rust_2021_prefixes_incompatible_syntax` lint detects identifiers that will be parsed as a
     /// prefix instead in Rust 2021.