Add safety annotations in iter::range

CAD97 · CAD97 · commit 27d1cd857e89 · 2020-05-21T13:44:54.000-04:00
diff --git a/src/libcore/iter/range.rs b/src/libcore/iter/range.rs
@@ -427,6 +427,8 @@ unsafe impl Step for char {
             res = Step::forward_checked(res, 0x800)?;
         }
         if res <= char::MAX as u32 {
+            // SAFETY: res is a valid unicode scalar
+            // (below 0x110000 and not in 0xD800..0xE000)
             Some(unsafe { char::from_u32_unchecked(res) })
         } else {
             None
@@ -440,6 +442,8 @@ unsafe impl Step for char {
         if start >= 0xE000 && 0xE000 > res {
             res = Step::backward_checked(res, 0x800)?;
         }
+        // SAFETY: res is a valid unicode scalar
+        // (below 0x110000 and not in 0xD800..0xE000)
         Some(unsafe { char::from_u32_unchecked(res) })
     }
 

Original file line number	Diff line number	Diff line change
`@@ -427,6 +427,8 @@ unsafe impl Step for char {`
`427`	`427`	`res = Step::forward_checked(res, 0x800)?;`
`428`	`428`	`}`
`429`	`429`	`if res <= char::MAX as u32 {`
	`430`	`+ // SAFETY: res is a valid unicode scalar`
	`431`	`+ // (below 0x110000 and not in 0xD800..0xE000)`
`430`	`432`	`Some(unsafe { char::from_u32_unchecked(res) })`
`431`	`433`	`} else {`
`432`	`434`	`None`
`@@ -440,6 +442,8 @@ unsafe impl Step for char {`
`440`	`442`	`if start >= 0xE000 && 0xE000 > res {`
`441`	`443`	`res = Step::backward_checked(res, 0x800)?;`
`442`	`444`	`}`
	`445`	`+ // SAFETY: res is a valid unicode scalar`
	`446`	`+ // (below 0x110000 and not in 0xD800..0xE000)`
`443`	`447`	`Some(unsafe { char::from_u32_unchecked(res) })`
`444`	`448`	`}`
`445`	`449`