Author: ericwf
Date: Wed Aug 22 10:47:13 2018
New Revision: 340426
URL: http://llvm.org/viewvc/llvm-project?rev=340426&view=rev
Log:
Add diagnostics for min/max algorithms when a InputIterator is used.
These algorithms require a ForwardIterator or better. Ensure
we diagnose the contract violation at compile time instead of
of silently doing the wrong thing.
Further algorithms will be audited in upcoming patches.
Added:
libcxx/trunk/test/std/algorithms/alg.sorting/alg.min.max/requires_forward_iterator.fail.cpp
Modified:
libcxx/trunk/include/algorithm
Modified: libcxx/trunk/include/algorithm
URL:
http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/algorithm?rev=340426&r1=340425&r2=340426&view=diff
==============================================================================
--- libcxx/trunk/include/algorithm (original)
+++ libcxx/trunk/include/algorithm Wed Aug 22 10:47:13 2018
@@ -2398,6 +2398,8 @@ inline _LIBCPP_INLINE_VISIBILITY _LIBCPP
_ForwardIterator
min_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
{
+ static_assert(__is_forward_iterator<_ForwardIterator>::value,
+ "std::min_element requires a ForwardIterator");
if (__first != __last)
{
_ForwardIterator __i = __first;
@@ -2462,6 +2464,8 @@ inline _LIBCPP_INLINE_VISIBILITY _LIBCPP
_ForwardIterator
max_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
{
+ static_assert(__is_forward_iterator<_ForwardIterator>::value,
+ "std::max_element requires a ForwardIterator");
if (__first != __last)
{
_ForwardIterator __i = __first;
@@ -2548,6 +2552,8 @@ _LIBCPP_CONSTEXPR_AFTER_CXX11
std::pair<_ForwardIterator, _ForwardIterator>
minmax_element(_ForwardIterator __first, _ForwardIterator __last, _Compare
__comp)
{
+ static_assert(__is_forward_iterator<_ForwardIterator>::value,
+ "std::minmax_element requires a ForwardIterator");
std::pair<_ForwardIterator, _ForwardIterator> __result(__first, __first);
if (__first != __last)
{
Added:
libcxx/trunk/test/std/algorithms/alg.sorting/alg.min.max/requires_forward_iterator.fail.cpp
URL:
http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/algorithms/alg.sorting/alg.min.max/requires_forward_iterator.fail.cpp?rev=340426&view=auto
==============================================================================
---
libcxx/trunk/test/std/algorithms/alg.sorting/alg.min.max/requires_forward_iterator.fail.cpp
(added)
+++
libcxx/trunk/test/std/algorithms/alg.sorting/alg.min.max/requires_forward_iterator.fail.cpp
Wed Aug 22 10:47:13 2018
@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <algorithm>
+
+// template<ForwardIterator Iter>
+// max_element(Iter first, Iter last);
+
+#include <algorithm>
+#include <cassert>
+
+#include "test_iterators.h"
+
+int main() {
+ int arr[] = {1, 2, 3};
+ const int *b = std::begin(arr), *e = std::end(arr);
+ typedef input_iterator<const int*> Iter;
+ {
+ // expected-error@algorithm:* {{"std::min_element requires a
ForwardIterator"}}
+ std::min_element(Iter(b), Iter(e));
+ }
+ {
+ // expected-error@algorithm:* {{"std::max_element requires a
ForwardIterator"}}
+ std::max_element(Iter(b), Iter(e));
+ }
+ {
+ // expected-error@algorithm:* {{"std::minmax_element requires a
ForwardIterator"}}
+ std::minmax_element(Iter(b), Iter(e));
+ }
+
+}
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