Auto merge of #72717 - poliorcetics:try-from-int-to-nzint, r=dtolnay

Add TryFrom<{int}> for NonZero{int}

Adds `TryFrom<{int}> for NonZero{int}`.

It uses the existing `NonZero{int}::new()` and `Option::ok_or()` functions, meaning the checks are not repeated.

I also added tests, I tried to follow the convention I saw in the test file.

I also used `#[stable(feature = "nzint_try_from_int_conv", since = "1.46.0")]`, but I have no idea if the feature/version are correctly named or even correct.

1 files changed, 19 insertions, 0 deletions

diff --git a/src/libcore/tests/nonzero.rs b/src/libcore/tests/nonzero.rs
index 0227a66b863..48aec6d718d 100644
--- a/src/libcore/tests/nonzero.rs
+++ b/src/libcore/tests/nonzero.rs
@@ -1,3 +1,4 @@
+use core::convert::TryFrom;
 use core::num::{IntErrorKind, NonZeroI32, NonZeroI8, NonZeroU32, NonZeroU8};
 use core::option::Option::{self, None, Some};
 use std::mem::size_of;
@@ -176,3 +177,21 @@ fn test_nonzero_bitor_assign() {
     target |= 0;
     assert_eq!(target.get(), 0b1011_1111);
 }
+
+#[test]
+fn test_nonzero_from_int_on_success() {
+    assert_eq!(NonZeroU8::try_from(5), Ok(NonZeroU8::new(5).unwrap()));
+    assert_eq!(NonZeroU32::try_from(5), Ok(NonZeroU32::new(5).unwrap()));
+
+    assert_eq!(NonZeroI8::try_from(-5), Ok(NonZeroI8::new(-5).unwrap()));
+    assert_eq!(NonZeroI32::try_from(-5), Ok(NonZeroI32::new(-5).unwrap()));
+}
+
+#[test]
+fn test_nonzero_from_int_on_err() {
+    assert!(NonZeroU8::try_from(0).is_err());
+    assert!(NonZeroU32::try_from(0).is_err());
+
+    assert!(NonZeroI8::try_from(0).is_err());
+    assert!(NonZeroI32::try_from(0).is_err());
+}