Rollup merge of #45133 - GuillaumeGomez:usize-index-msg, r=dtolnay

usize index message for vec

src/liballoc/lib.rs

@@ -121,6 +121,7 @@
 #![feature(unique)]
 #![feature(unsize)]
 #![feature(allocator_internals)]
+#![feature(on_unimplemented)]
 
 #![cfg_attr(not(test), feature(fused, fn_traits, placement_new_protocol, swap_with_slice, i128))]
 #![cfg_attr(test, feature(test, box_heap))]

src/liballoc/vec.rs

@@ -1543,6 +1543,7 @@ impl<T: Hash> Hash for Vec<T> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
 impl<T> Index<usize> for Vec<T> {
     type Output = T;
 
@@ -1554,6 +1555,7 @@ impl<T> Index<usize> for Vec<T> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
 impl<T> IndexMut<usize> for Vec<T> {
     #[inline]
     fn index_mut(&mut self, index: usize) -> &mut T {
@@ -1562,8 +1564,8 @@ impl<T> IndexMut<usize> for Vec<T> {
     }
 }
 
-
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
 impl<T> ops::Index<ops::Range<usize>> for Vec<T> {
     type Output = [T];
 
@@ -1572,7 +1574,9 @@ impl<T> ops::Index<ops::Range<usize>> for Vec<T> {
         Index::index(&**self, index)
     }
 }
+
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
 impl<T> ops::Index<ops::RangeTo<usize>> for Vec<T> {
     type Output = [T];
 
@@ -1581,7 +1585,9 @@ impl<T> ops::Index<ops::RangeTo<usize>> for Vec<T> {
         Index::index(&**self, index)
     }
 }
+
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
 impl<T> ops::Index<ops::RangeFrom<usize>> for Vec<T> {
     type Output = [T];
 
@@ -1590,7 +1596,9 @@ impl<T> ops::Index<ops::RangeFrom<usize>> for Vec<T> {
         Index::index(&**self, index)
     }
 }
+
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
 impl<T> ops::Index<ops::RangeFull> for Vec<T> {
     type Output = [T];
 
@@ -1599,7 +1607,9 @@ impl<T> ops::Index<ops::RangeFull> for Vec<T> {
         self
     }
 }
+
 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
 impl<T> ops::Index<ops::RangeInclusive<usize>> for Vec<T> {
     type Output = [T];
 
@@ -1608,7 +1618,9 @@ impl<T> ops::Index<ops::RangeInclusive<usize>> for Vec<T> {
         Index::index(&**self, index)
     }
 }
+
 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
 impl<T> ops::Index<ops::RangeToInclusive<usize>> for Vec<T> {
     type Output = [T];
 
@@ -1619,41 +1631,52 @@ impl<T> ops::Index<ops::RangeToInclusive<usize>> for Vec<T> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
 impl<T> ops::IndexMut<ops::Range<usize>> for Vec<T> {
     #[inline]
     fn index_mut(&mut self, index: ops::Range<usize>) -> &mut [T] {
         IndexMut::index_mut(&mut **self, index)
     }
 }
+
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
 impl<T> ops::IndexMut<ops::RangeTo<usize>> for Vec<T> {
     #[inline]
     fn index_mut(&mut self, index: ops::RangeTo<usize>) -> &mut [T] {
         IndexMut::index_mut(&mut **self, index)
     }
 }
+
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
 impl<T> ops::IndexMut<ops::RangeFrom<usize>> for Vec<T> {
     #[inline]
     fn index_mut(&mut self, index: ops::RangeFrom<usize>) -> &mut [T] {
         IndexMut::index_mut(&mut **self, index)
     }
 }
+
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
 impl<T> ops::IndexMut<ops::RangeFull> for Vec<T> {
     #[inline]
     fn index_mut(&mut self, _index: ops::RangeFull) -> &mut [T] {
         self
     }
 }
+
 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
 impl<T> ops::IndexMut<ops::RangeInclusive<usize>> for Vec<T> {
     #[inline]
     fn index_mut(&mut self, index: ops::RangeInclusive<usize>) -> &mut [T] {
         IndexMut::index_mut(&mut **self, index)
     }
 }
+
 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
 impl<T> ops::IndexMut<ops::RangeToInclusive<usize>> for Vec<T> {
     #[inline]
     fn index_mut(&mut self, index: ops::RangeToInclusive<usize>) -> &mut [T] {

src/test/compile-fail/index-help.rs

@@ -0,0 +1,15 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    let x = vec![1];
+    x[0i32]; //~ ERROR E0277
+             //~| NOTE vector indices are of type `usize` or ranges of `usize`
+}