Auto merge of #79233 - yoshuawuyts:alloc-doc-alias, r=GuillaumeGomez

Add doc aliases for memory allocations

This patch adds doc aliases for various C allocation functions, making it possible to search for the C-equivalent of a function and finding the (safe) Rust counterpart:

- `Vec::with_capacity` / `Box::new` / `vec!` -> alloc + malloc, allocates memory
- `Box::new_zeroed` -> calloc, allocates zeroed-out memory
- `Vec::{reserve,reserve_exact,try_reserve_exact,shrink_to_fit,shrink_to}` -> realloc, reallocates a previously allocated slice of memory

It's worth noting that `Vec::new` does not allocate, so we don't link to it. Instead people are probably looking for `Vec::with_capacity` or `vec!`. I hope this will allow people comfortable with the system allocation APIs to make it easier to find what they may be looking for.

Thanks!

library/alloc/src/boxed.rs

@@ -178,8 +178,10 @@ impl<T> Box<T> {
     /// ```
     /// let five = Box::new(5);
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     #[inline(always)]
+    #[doc(alias = "alloc")]
+    #[doc(alias = "malloc")]
+    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn new(x: T) -> Self {
         box x
     }
@@ -226,8 +228,9 @@ impl<T> Box<T> {
     /// ```
     ///
     /// [zeroed]: mem::MaybeUninit::zeroed
-    #[unstable(feature = "new_uninit", issue = "63291")]
     #[inline]
+    #[doc(alias = "calloc")]
+    #[unstable(feature = "new_uninit", issue = "63291")]
     pub fn new_zeroed() -> Box<mem::MaybeUninit<T>> {
         Self::new_zeroed_in(Global)
     }

library/alloc/src/macros.rs

@@ -35,6 +35,8 @@
 ///
 /// [`Vec`]: crate::vec::Vec
 #[cfg(not(test))]
+#[doc(alias = "alloc")]
+#[doc(alias = "malloc")]
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[allow_internal_unstable(box_syntax, liballoc_internals)]

library/alloc/src/string.rs

@@ -403,6 +403,8 @@ impl String {
     /// s.push('a');
     /// ```
     #[inline]
+    #[doc(alias = "alloc")]
+    #[doc(alias = "malloc")]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn with_capacity(capacity: usize) -> String {
         String { vec: Vec::with_capacity(capacity) }

library/alloc/src/vec/mod.rs

@@ -433,6 +433,7 @@ impl<T> Vec<T> {
     /// assert!(vec.capacity() >= 11);
     /// ```
     #[inline]
+    #[doc(alias = "malloc")]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn with_capacity(capacity: usize) -> Self {
         Self::with_capacity_in(capacity, Global)
@@ -766,6 +767,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// vec.reserve(10);
     /// assert!(vec.capacity() >= 11);
     /// ```
+    #[doc(alias = "realloc")]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn reserve(&mut self, additional: usize) {
         self.buf.reserve(self.len, additional);
@@ -791,6 +793,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// vec.reserve_exact(10);
     /// assert!(vec.capacity() >= 11);
     /// ```
+    #[doc(alias = "realloc")]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn reserve_exact(&mut self, additional: usize) {
         self.buf.reserve_exact(self.len, additional);
@@ -828,6 +831,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// }
     /// # process_data(&[1, 2, 3]).expect("why is the test harness OOMing on 12 bytes?");
     /// ```
+    #[doc(alias = "realloc")]
     #[unstable(feature = "try_reserve", reason = "new API", issue = "48043")]
     pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> {
         self.buf.try_reserve(self.len, additional)
@@ -869,6 +873,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// }
     /// # process_data(&[1, 2, 3]).expect("why is the test harness OOMing on 12 bytes?");
     /// ```
+    #[doc(alias = "realloc")]
     #[unstable(feature = "try_reserve", reason = "new API", issue = "48043")]
     pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), TryReserveError> {
         self.buf.try_reserve_exact(self.len, additional)
@@ -888,6 +893,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// vec.shrink_to_fit();
     /// assert!(vec.capacity() >= 3);
     /// ```
+    #[doc(alias = "realloc")]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn shrink_to_fit(&mut self) {
         // The capacity is never less than the length, and there's nothing to do when
@@ -920,6 +926,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// vec.shrink_to(0);
     /// assert!(vec.capacity() >= 3);
     /// ```
+    #[doc(alias = "realloc")]
     #[unstable(feature = "shrink_to", reason = "new API", issue = "56431")]
     pub fn shrink_to(&mut self, min_capacity: usize) {
         self.buf.shrink_to_fit(cmp::max(self.len, min_capacity));