Detailed panic messages for Vec functions

src/liballoc/vec.rs

@@ -964,8 +964,16 @@ impl<T> Vec<T> {
  #[inline]
  #[stable(feature = "rust1", since = "1.0.0")]
  pub fn swap_remove(&mut self, index: usize) -> T {
+ #[cold]
+ #[inline(never)]
+ fn assert_failed(index: usize, len: usize) -> ! {
+ panic!("swap_remove index (is {}) should be < len (is {})", index, len);
+ }
+
  let len = self.len();
- assert!(index < len);
+ if !(index < len) {
+ assert_failed(index, len);
+ }
  unsafe {
  // We replace self[index] with the last element. Note that if the
  // bounds check above succeeds there must be a last element (which
@@ -995,8 +1003,16 @@ impl<T> Vec<T> {
  /// ```
  #[stable(feature = "rust1", since = "1.0.0")]
  pub fn insert(&mut self, index: usize, element: T) {
+ #[cold]
+ #[inline(never)]
+ fn assert_failed(index: usize, len: usize) -> ! {
+ panic!("insertion index (is {}) should be <= len (is {})", index, len);
+ }
+
  let len = self.len();
- assert!(index <= len);
+ if !(index <= len) {
+ assert_failed(index, len);
+ }
 
  // space for the new element
  if len == self.buf.capacity() {
@@ -1035,8 +1051,16 @@ impl<T> Vec<T> {
  /// ```
  #[stable(feature = "rust1", since = "1.0.0")]
  pub fn remove(&mut self, index: usize) -> T {
+ #[cold]
+ #[inline(never)]
+ fn assert_failed(index: usize, len: usize) -> ! {
+ panic!("removal index (is {}) should be < len (is {})", index, len);
+ }
+
  let len = self.len();
- assert!(index < len);
+ if !(index < len) {
+ assert_failed(index, len);
+ }
  unsafe {
  // infallible
  let ret;
@@ -1294,8 +1318,25 @@ impl<T> Vec<T> {
  Excluded(&n) => n,
  Unbounded => len,
  };
- assert!(start <= end);
- assert!(end <= len);
+
+ #[cold]
+ #[inline(never)]
+ fn start_assert_failed(start: usize, end: usize) -> ! {
+ panic!("start drain index (is {}) should be <= end drain index (is {})", start, end);
+ }
+
+ #[cold]
+ #[inline(never)]
+ fn end_assert_failed(end: usize, len: usize) -> ! {
+ panic!("end drain index (is {}) should be <= len (is {})", end, len);
+ }
+
+ if !(start <= end) {
+ start_assert_failed(start, end);
+ }
+ if !(end <= len) {
+ end_assert_failed(end, len);
+ }
 
  unsafe {
  // set self.vec length's to start, to be safe in case Drain is leaked
@@ -1385,7 +1426,15 @@ impl<T> Vec<T> {
  #[must_use = "use `.truncate()` if you don't need the other half"]
  #[stable(feature = "split_off", since = "1.4.0")]
  pub fn split_off(&mut self, at: usize) -> Self {
- assert!(at <= self.len(), "`at` out of bounds");
+ #[cold]
+ #[inline(never)]
+ fn assert_failed(at: usize, len: usize) -> ! {
+ panic!("`at` split index (is {}) should be <= len (is {})", at, len);
+ }
+
+ if !(at <= self.len()) {
+ assert_failed(at, self.len());
+ }
 
  let other_len = self.len - at;
  let mut other = Vec::with_capacity(other_len);