tests

Author: Randl

library/core/src/net/socket_addr.rs

@@ -1,5 +1,6 @@
 use super::display_buffer::DisplayBuffer;
 use crate::fmt::{self, Write};
+use crate::marker::Destruct;
 use crate::net::{IpAddr, Ipv4Addr, Ipv6Addr};
 
 /// An internet socket address, either IPv4 or IPv6.
@@ -612,7 +613,8 @@ impl const From<SocketAddrV6> for SocketAddr {
 }
 
 #[stable(feature = "addr_from_into_ip", since = "1.17.0")]
-impl<I: Into<IpAddr>> From<(I, u16)> for SocketAddr {
+#[rustc_const_unstable(feature = "const_trait_impl", issue = "67792")]
+impl<I: ~const Into<IpAddr> + ~const Destruct> const From<(I, u16)> for SocketAddr {
     /// Converts a tuple struct (Into<[`IpAddr`]>, `u16`) into a [`SocketAddr`].
     ///
     /// This conversion creates a [`SocketAddr::V4`] for an [`IpAddr::V4`]

library/core/src/num/nonzero.rs

@@ -296,7 +296,8 @@ where
 }
 
 #[stable(feature = "from_nonzero", since = "1.31.0")]
-impl<T> From<NonZero<T>> for T
+#[rustc_const_unstable(feature = "const_trait_impl", issue = "67792")]
+impl<T> const From<NonZero<T>> for T
 where
     T: ZeroablePrimitive,
 {

library/core/src/result.rs

@@ -534,6 +534,7 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use crate::iter::{self, FusedIterator, TrustedLen};
+use crate::marker::Destruct;
 use crate::ops::{self, ControlFlow, Deref, DerefMut};
 use crate::{convert, fmt, hint};
 

tests/ui/traits/const-traits/const-from.rs

@@ -0,0 +1,80 @@
+// tests/const_conversion_tests.rs
+#![feature(const_trait_impl,f16, f128)]
+#![feature(ascii_char, ascii_char_variants)]
+
+use std::convert::TryFrom;
+use std::net::{Ipv4Addr, IpAddr, SocketAddr};
+use std::str::FromStr;
+use std::num::NonZero;
+use std::ascii::Char as AsciiChar;
+
+const _: () = {
+    // --- From<AsciiChar> / From<char> / TryFrom<u32> for char ---
+    let ac = AsciiChar::LessThanSign;
+    let _: u8   = u8::from(ac);
+    let _: u16  = u16::from(ac);
+    let _: u32  = u32::from(ac);
+    let _: u64  = u64::from(ac);
+    let _: u128 = u128::from(ac);
+    let _: char = char::from(ac);
+
+    let c = '🚀';
+    let _: u32  = u32::from(c);
+    let _: u64  = u64::from(c);
+    let _: u128 = u128::from(c);
+    let _: char = char::from(65u8);
+    let _: char = char::try_from(0x1F680u32).unwrap();
+
+
+    let mut st = String::from("world");
+    //~^ ERROR: the trait bound `String: const From<&str>` is not satisfied
+
+    // --- AsRef / AsMut on primitive refs, arrays, strings ---
+    let x = &5u8;
+    let _: &u8      = x.as_ref();
+    //~^ ERROR: the method `as_ref` exists for reference `&u8`, but its trait bounds were not satisfied
+    let mut y = 6u8;
+    let ym = &mut y;
+    let _: &mut u8  = ym.as_mut();
+    //~^ ERROR: the method `as_mut` exists for mutable reference `&mut u8`, but its trait bounds were not satisfied
+
+    let arr      = [1u8, 2, 3];
+    let _: &[u8] = arr.as_ref();
+    //~^ ERROR: the trait bound `[u8; 3]: const AsRef<[u8]>` is not satisfied [E0277]
+    let mut arr2 = [4u8, 5, 6];
+    let _: &mut [u8] = arr2.as_mut();
+    //~^ ERROR: the trait bound `[u8; 3]: const AsMut<[u8]>` is not satisfied [E0277]
+
+    let s  = "hello";
+    let _: &str     = s.as_ref();
+
+    // --- bool → integers, isize ↔ usize ---
+    let b = true;
+    let _: u8    = u8::from(b);
+    let _: i8    = i8::from(b);
+    let _: u16   = u16::from(b);
+    let _: i16   = i16::from(b);
+    let _: usize = usize::from(b);
+    let _: isize = isize::from(b);
+
+    let _ = usize::try_from(42_isize);
+    let _ = isize::try_from(42_usize);
+
+    // --- NonZero conversions ---
+    let nz8  = unsafe { NonZero::new_unchecked(5)};
+    let _   = NonZero::<u16>::from(nz8);
+    let _         = u8::from(nz8);
+
+    // --- IpAddr / SocketAddr ---
+    let v4 = Ipv4Addr::new(127, 0, 0, 1);
+    let _: u32      = u32::from(v4);
+    let _: SocketAddr  = SocketAddr::from((v4, 8080));
+
+    // --- FromStr for ints  ---
+    let _: u8   = u8::from_str("123").unwrap();
+    let _: i16  = i16::from_str("-456").unwrap();
+
+    ();
+};
+
+fn main() {}

tests/ui/traits/const-traits/const-from.stderr

@@ -0,0 +1,42 @@
+error[E0277]: the trait bound `String: const From<&str>` is not satisfied
+  --> $DIR/const-from.rs:29:18
+   |
+LL |     let mut st = String::from("world");
+   |                  ^^^^^^
+
+error[E0599]: the method `as_ref` exists for reference `&u8`, but its trait bounds were not satisfied
+  --> $DIR/const-from.rs:34:25
+   |
+LL |     let _: &u8      = x.as_ref();
+   |                         ^^^^^^ method cannot be called on `&u8` due to unsatisfied trait bounds
+   |
+   = note: the following trait bounds were not satisfied:
+           `u8: AsRef<_>`
+           which is required by `&u8: AsRef<_>`
+
+error[E0599]: the method `as_mut` exists for mutable reference `&mut u8`, but its trait bounds were not satisfied
+  --> $DIR/const-from.rs:38:26
+   |
+LL |     let _: &mut u8  = ym.as_mut();
+   |                          ^^^^^^ method cannot be called on `&mut u8` due to unsatisfied trait bounds
+   |
+   = note: the following trait bounds were not satisfied:
+           `u8: AsMut<_>`
+           which is required by `&mut u8: AsMut<_>`
+
+error[E0277]: the trait bound `[u8; 3]: const AsRef<[u8]>` is not satisfied
+  --> $DIR/const-from.rs:42:24
+   |
+LL |     let _: &[u8] = arr.as_ref();
+   |                        ^^^^^^
+
+error[E0277]: the trait bound `[u8; 3]: const AsMut<[u8]>` is not satisfied
+  --> $DIR/const-from.rs:45:29
+   |
+LL |     let _: &mut [u8] = arr2.as_mut();
+   |                             ^^^^^^
+
+error: aborting due to 5 previous errors
+
+Some errors have detailed explanations: E0277, E0599.
+For more information about an error, try `rustc --explain E0277`.