Auto merge of #148049 - cuviper:revert-hash_map, r=Mark-Simulacrum

Revert "feat: implement `hash_map!` macro"

Crater for 1.91-beta found that this unstable macro caused ambiguity in the ecosystem: #147971

Since we are very close to release, it's probably best to just revert the macro for now, and re-add it later in a less invasive way -- i.e. not a top-level macro, and not in the prelude until a future edition (as noted [here](https://std-dev-guide.rust-lang.org/breaking-changes/prelude.html#macros)).

`@rustbot` label beta-nominated

Author: bors

library/std/src/lib.rs

@@ -290,8 +290,6 @@
 #![feature(ffi_const)]
 #![feature(formatting_options)]
 #![feature(funnel_shifts)]
-#![feature(hash_map_internals)]
-#![feature(hash_map_macro)]
 #![feature(if_let_guard)]
 #![feature(intra_doc_pointers)]
 #![feature(iter_advance_by)]

library/std/src/macros.rs

@@ -379,77 +379,3 @@ macro_rules! dbg {
         ($($crate::dbg!($val)),+,)
     };
 }
-
-#[doc(hidden)]
-#[macro_export]
-#[allow_internal_unstable(hash_map_internals)]
-#[unstable(feature = "hash_map_internals", issue = "none")]
-macro_rules! repetition_utils {
-    (@count $($tokens:tt),*) => {{
-        [$($crate::repetition_utils!(@replace $tokens => ())),*].len()
-    }};
-
-    (@replace $x:tt => $y:tt) => { $y }
-}
-
-/// Creates a [`HashMap`] containing the arguments.
-///
-/// `hash_map!` allows specifying the entries that make
-/// up the [`HashMap`] where the key and value are separated by a `=>`.
-///
-/// The entries are separated by commas with a trailing comma being allowed.
-///
-/// It is semantically equivalent to using repeated [`HashMap::insert`]
-/// on a newly created hashmap.
-///
-/// `hash_map!` will attempt to avoid repeated reallocations by
-/// using [`HashMap::with_capacity`].
-///
-/// # Examples
-///
-/// ```rust
-/// #![feature(hash_map_macro)]
-///
-/// let map = hash_map! {
-///     "key" => "value",
-///     "key1" => "value1"
-/// };
-///
-/// assert_eq!(map.get("key"), Some(&"value"));
-/// assert_eq!(map.get("key1"), Some(&"value1"));
-/// assert!(map.get("brrrrrrooooommm").is_none());
-/// ```
-///
-/// And with a trailing comma
-///
-///```rust
-/// #![feature(hash_map_macro)]
-///
-/// let map = hash_map! {
-///     "key" => "value", // notice the ,
-/// };
-///
-/// assert_eq!(map.get("key"), Some(&"value"));
-/// ```
-///
-/// The key and value are moved into the HashMap.
-///
-/// [`HashMap`]: crate::collections::HashMap
-/// [`HashMap::insert`]: crate::collections::HashMap::insert
-/// [`HashMap::with_capacity`]: crate::collections::HashMap::with_capacity
-#[macro_export]
-#[allow_internal_unstable(hash_map_internals)]
-#[unstable(feature = "hash_map_macro", issue = "144032")]
-macro_rules! hash_map {
-    () => {{
-        $crate::collections::HashMap::new()
-    }};
-
-    ( $( $key:expr => $value:expr ),* $(,)? ) => {{
-        let mut map = $crate::collections::HashMap::with_capacity(
-            const { $crate::repetition_utils!(@count $($key),*) }
-        );
-        $( map.insert($key, $value); )*
-        map
-    }}
-}

library/std/tests/ambiguous-hash_map.rs

@@ -0,0 +1,17 @@
+//! Make sure that a `std` macro `hash_map!` does not cause ambiguity
+//! with a local glob import with the same name.
+//!
+//! See regression https://github.com/rust-lang/rust/issues/147971
+
+mod module {
+    macro_rules! hash_map {
+        () => {};
+    }
+    pub(crate) use hash_map;
+}
+
+use module::*;
+
+fn main() {
+    hash_map! {}
+}