core: Add core::ffi::c_intptr_t and core::ffi::c_uintptr_t

This is a complement to c_ptrdiff_t

Tracking issue: #88345

Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>

Author: lygstate

library/core/src/ffi/mod.rs

@@ -38,7 +38,7 @@ pub use self::primitives::{
     c_ulong, c_ulonglong, c_ushort,
 };
 #[unstable(feature = "c_size_t", issue = "88345")]
-pub use self::primitives::{c_ptrdiff_t, c_size_t, c_ssize_t};
+pub use self::primitives::{c_ptrdiff_t, c_size_t, c_ssize_t, c_intptr_t, c_uintptr_t};
 
 // N.B., for LLVM to recognize the void pointer type and by extension
 //     functions like malloc(), we need to have it represented as i8* in

library/core/src/ffi/primitives.rs

@@ -174,6 +174,24 @@ pub type c_ptrdiff_t = isize;
 #[unstable(feature = "c_size_t", issue = "88345")]
 pub type c_ssize_t = isize;
 
+/// Equivalent to C's `intptr_t` type.
+///
+/// This type is currently always [`isize`], however in the future there may be
+/// platforms where this is not the case. The C standard technically only
+/// requires that this type be a signed integer type just capable of holding a
+/// pointer.
+#[unstable(feature = "c_size_t", issue = "88345")]
+pub type c_intptr_t = isize;
+
+/// Equivalent to C's `uintptr_t` type.
+///
+/// This type is currently always [`usize`], however in the future there may be
+/// platforms where this is not the case. The C standard technically only
+/// requires that this type be an unsigned integer type just capable of holding a
+/// pointer.
+#[unstable(feature = "c_size_t", issue = "88345")]
+pub type c_uintptr_t = usize;
+
 mod c_int_definition {
     crate::cfg_select! {
         any(target_arch = "avr", target_arch = "msp430") => {