fix ptr invalidation in Vec::truncate

RalfJung · RalfJung · commit fa6c88307408 · 2020-03-30T11:58:16.000+02:00
diff --git a/src/liballoc/vec.rs b/src/liballoc/vec.rs
@@ -739,7 +739,8 @@ impl<T> Vec<T> {
             if len > self.len {
                 return;
             }
-            let s = self.get_unchecked_mut(len..) as *mut _;
+            let remaining_len = self.len - len;
+            let s = slice::from_raw_parts_mut(self.as_mut_ptr().add(len), remaining_len);
             self.len = len;
             ptr::drop_in_place(s);
         }

Original file line number	Diff line number	Diff line change
`@@ -739,7 +739,8 @@ impl<T> Vec<T> {`
`739`	`739`	`if len > self.len {`
`740`	`740`	`return;`
`741`	`741`	`}`
`742`		`- let s = self.get_unchecked_mut(len..) as *mut _;`
	`742`	`+ let remaining_len = self.len - len;`
	`743`	`+ let s = slice::from_raw_parts_mut(self.as_mut_ptr().add(len), remaining_len);`
`743`	`744`	`self.len = len;`
`744`	`745`	`ptr::drop_in_place(s);`
`745`	`746`	`}`