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Auto merge of #25013 - pnkfelix:span_to_lines-oflo, r=huonw

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Guard against overflow in `codemap::span_to_lines`.

(Revised/expanded version of PR #24976)

Make `span_to_lines` to return a `Result`.

In `diagnostic`, catch `Err` from `span_to_lines` and print `"(unprintable span)"` instead.

----

There a number of recent issues that report the bug here.  See e.g. #24761 and #24954.

This change *might* fix them. However, that is *not* its main goal. The main goals are:

 1. Make it possible for callers to recover from an error here, and

 2. Insert a more conservative check, in that we are also checking that the files match up.

----

As a drive-by, fix #24997 , which was causing my attempts to `make check-stage1` on an `--enable-debug` build to fail.
This commit is contained in:
bors
2015-05-07 15:25:09 +00:00
parent 05d5fcaa5b 939e4c9ea9
commit a39d4fc684
3 changed files with 69 additions and 14 deletions
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30
src/libcore/slice.rs
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@@ -631,8 +631,14 @@ fn size_from_ptr<T>(_: *const T) -> usize {
}
// Use macro to be generic over const/mut
macro_rules! slice_offset {
// Use macros to be generic over const/mut
//
// They require non-negative `$by` because otherwise the expression
// `(ptr as usize + $by)` would interpret `-1` as `usize::MAX` (and
// thus trigger a panic when overflow checks are on).
// Use this to do `$ptr + $by`, where `$by` is non-negative.
macro_rules! slice_add_offset {
($ptr:expr, $by:expr) => {{
let ptr = $ptr;
if size_from_ptr(ptr) == 0 {
@@ -643,6 +649,18 @@ macro_rules! slice_offset {
}};
}
// Use this to do `$ptr - $by`, where `$by` is non-negative.
macro_rules! slice_sub_offset {
($ptr:expr, $by:expr) => {{
let ptr = $ptr;
if size_from_ptr(ptr) == 0 {
transmute(ptr as usize - $by)
} else {
ptr.offset(-$by)
}
}};
}
macro_rules! slice_ref {
($ptr:expr) => {{
let ptr = $ptr;
@@ -672,7 +690,7 @@ macro_rules! iterator {
None
} else {
let old = self.ptr;
self.ptr = slice_offset!(self.ptr, 1);
self.ptr = slice_add_offset!(self.ptr, 1);
Some(slice_ref!(old))
}
}
@@ -714,7 +732,7 @@ macro_rules! iterator {
if self.end == self.ptr {
None
} else {
self.end = slice_offset!(self.end, -1);
self.end = slice_sub_offset!(self.end, 1);
Some(slice_ref!(self.end))
}
}
@@ -776,7 +794,7 @@ impl<'a, T> Iter<'a, T> {
fn iter_nth(&mut self, n: usize) -> Option<&'a T> {
match self.as_slice().get(n) {
Some(elem_ref) => unsafe {
self.ptr = slice_offset!(elem_ref as *const _, 1);
self.ptr = slice_add_offset!(elem_ref as *const _, 1);
Some(slice_ref!(elem_ref))
},
None => {
@@ -849,7 +867,7 @@ impl<'a, T> IterMut<'a, T> {
fn iter_nth(&mut self, n: usize) -> Option<&'a mut T> {
match make_mut_slice!(T => &'a mut [T]: self.ptr, self.end).get_mut(n) {
Some(elem_ref) => unsafe {
self.ptr = slice_offset!(elem_ref as *mut _, 1);
self.ptr = slice_add_offset!(elem_ref as *mut _, 1);
Some(slice_ref!(elem_ref))
},
None => {