[libc++] Fix build failure with _LIBCPP_DEBUG=0 when iterators return values instead of references
There are many STL algorithms (such as lexicographical_compare) that compare
values pointed to by iterators like so:
__comp(*it1, *it2);
When building with `_LIBCPP_DEBUG=0`, comparators are wrapped in `__debug_less`
which does some additional validation. But `__debug_less::operator()` takes
non-const references, so if the type of `*it1` is int, not int&, then the build
will fail.
This change adds a `const&` overload for `operator()` to fix the build.
Differential Revision: https://reviews.llvm.org/D60592
llvm-svn: 358423
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
index 22adcc8..244ae2d 100644
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -785,6 +785,15 @@
__debug_less(_Compare& __c) : __comp_(__c) {}
template <class _Tp, class _Up>
+ bool operator()(const _Tp& __x, const _Up& __y)
+ {
+ bool __r = __comp_(__x, __y);
+ if (__r)
+ __do_compare_assert(0, __y, __x);
+ return __r;
+ }
+
+ template <class _Tp, class _Up>
_LIBCPP_CONSTEXPR_AFTER_CXX17
bool operator()(_Tp& __x, _Up& __y)
{
