[gcc/devel/autopar_devel] libstdc++: Make relational operators work with const guarded iterators (PR 92472)

[Giuliano Belinassi]

https://gcc.gnu.org/g:01305f5d86ea73a3a9d84b51c1dceead99603550

commit 01305f5d86ea73a3a9d84b51c1dceead99603550
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu May 7 21:43:49 2020 +0100

    libstdc++: Make relational operators work with const guarded iterators (PR 92472)
    
    This is a correct fix for the incorrect cppcheck suggestion to make
    these parameters const. In order to that, the dereference operators need
    to be const. The conversions to the underlying iterator can be const
    too.
    
            PR c/92472
            * include/parallel/multiway_merge.h (_GuardedIterator::operator*)
            (_GuardedIterator::operator _RAIter, _UnguardedIterator::operator*)
            (_UnguardedIterator::operator _RAIter): Add const qualifier.
            (operator<(_GuardedIterator&, _GuardedIterator&)
            (operator<=(_GuardedIterator&, _GuardedIterator&)
            (operator<(_UnguardedIterator&, _UnguardedIterator&)
            (operator<=(_UnguardedIterator&, _UnguardedIterator&): Change
            parameters to const references.

Diff:
---
 libstdc++-v3/ChangeLog                         | 12 ++++++++++++
 libstdc++-v3/include/parallel/multiway_merge.h | 24 ++++++++++++------------
 2 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index f5c278e5d58..d0751909dd2 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -27,6 +27,18 @@
 	* config/abi/post/sparc-solaris/sparcv9/baseline_symbols.txt:
 	Likewise.
 
+2020-05-07  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR c/92472
+	* include/parallel/multiway_merge.h (_GuardedIterator::operator*)
+	(_GuardedIterator::operator _RAIter, _UnguardedIterator::operator*)
+	(_UnguardedIterator::operator _RAIter): Add const qualifier.
+	(operator<(_GuardedIterator&, _GuardedIterator&)
+	(operator<=(_GuardedIterator&, _GuardedIterator&)
+	(operator<(_UnguardedIterator&, _UnguardedIterator&)
+	(operator<=(_UnguardedIterator&, _UnguardedIterator&): Change
+	parameters to const references.
+
 2020-05-06  Martin Liska  <mliska@suse.cz>
 
 	Revert:
diff --git a/libstdc++-v3/include/parallel/multiway_merge.h b/libstdc++-v3/include/parallel/multiway_merge.h
index 983c7b2bd9a..52a8b2ca9e7 100644
--- a/libstdc++-v3/include/parallel/multiway_merge.h
+++ b/libstdc++-v3/include/parallel/multiway_merge.h
@@ -104,12 +104,12 @@ namespace __gnu_parallel
       /** @brief Dereference operator.
       *  @return Referenced element. */
       typename std::iterator_traits<_RAIter>::value_type&
-      operator*()
+      operator*() const
       { return *_M_current; }
 
       /** @brief Convert to wrapped iterator.
       *  @return Wrapped iterator. */
-      operator _RAIter()
+      operator _RAIter() const
       { return _M_current; }
 
       /** @brief Compare two elements referenced by guarded iterators.
@@ -117,8 +117,8 @@ namespace __gnu_parallel
        *  @param __bi2 Second iterator.
        *  @return @c true if less. */
       friend bool
-      operator<(_GuardedIterator<_RAIter, _Compare>& __bi1,
-		_GuardedIterator<_RAIter, _Compare>& __bi2)
+      operator<(const _GuardedIterator<_RAIter, _Compare>& __bi1,
+		const _GuardedIterator<_RAIter, _Compare>& __bi2)
       {
 	if (__bi1._M_current == __bi1._M_end)       // __bi1 is sup
 	  return __bi2._M_current == __bi2._M_end;  // __bi2 is not sup
@@ -132,8 +132,8 @@ namespace __gnu_parallel
        *  @param __bi2 Second iterator.
        *  @return @c True if less equal. */
       friend bool
-      operator<=(_GuardedIterator<_RAIter, _Compare>& __bi1,
-		 _GuardedIterator<_RAIter, _Compare>& __bi2)
+      operator<=(const _GuardedIterator<_RAIter, _Compare>& __bi1,
+		 const _GuardedIterator<_RAIter, _Compare>& __bi2)
       {
 	if (__bi2._M_current == __bi2._M_end)       // __bi1 is sup
 	  return __bi1._M_current != __bi1._M_end;  // __bi2 is not sup
@@ -174,12 +174,12 @@ namespace __gnu_parallel
       /** @brief Dereference operator.
       *  @return Referenced element. */
       typename std::iterator_traits<_RAIter>::value_type&
-      operator*()
+      operator*() const
       { return *_M_current; }
 
       /** @brief Convert to wrapped iterator.
       *  @return Wrapped iterator. */
-      operator _RAIter()
+      operator _RAIter() const
       { return _M_current; }
 
       /** @brief Compare two elements referenced by unguarded iterators.
@@ -187,8 +187,8 @@ namespace __gnu_parallel
        *  @param __bi2 Second iterator.
        *  @return @c true if less. */
       friend bool
-      operator<(_UnguardedIterator<_RAIter, _Compare>& __bi1,
-		_UnguardedIterator<_RAIter, _Compare>& __bi2)
+      operator<(const _UnguardedIterator<_RAIter, _Compare>& __bi1,
+		const _UnguardedIterator<_RAIter, _Compare>& __bi2)
       {
 	// Normal compare.
 	return (__bi1.__comp)(*__bi1, *__bi2);
@@ -199,8 +199,8 @@ namespace __gnu_parallel
        *  @param __bi2 Second iterator.
        *  @return @c True if less equal. */
       friend bool
-      operator<=(_UnguardedIterator<_RAIter, _Compare>& __bi1,
-		 _UnguardedIterator<_RAIter, _Compare>& __bi2)
+      operator<=(const _UnguardedIterator<_RAIter, _Compare>& __bi1,
+		 const _UnguardedIterator<_RAIter, _Compare>& __bi2)
       {
 	// Normal compare.
 	return !(__bi1.__comp)(*__bi2, *__bi1);