[gcc r13-5309] libstdc++: [_GLIBCXX_DEBUG] Remove useless constructor checks

[Francois Dumont <fdumont@gcc.gnu.org>]

https://gcc.gnu.org/g:c3c6c307792026705fe0398f5ee399f7668fed1b

commit r13-5309-gc3c6c307792026705fe0398f5ee399f7668fed1b
Author: François Dumont <fdumont@gcc.gnu.org>
Date:   Mon Jan 23 06:26:34 2023 +0100

    libstdc++: [_GLIBCXX_DEBUG] Remove useless constructor checks
    
    Creating a safe iterator from a normal iterator is done within the library where we
    already know that it is done correctly. The rare situation where a user would use safe
    iterators for his own purpose is non-Standard code so outside _GLIBCXX_DEBUG scope. For
    those reasons the __msg_init_singular is useless and can be removed.
    
    Additionally in the copy constructor used for post-increment and post-decrement operators
    the __msg_init_copy_singular check can also be ommitted because of the preliminary
    __msg_bad_incr and __msg_bad_decr checks.
    
    libstdc++-v3/ChangeLog:
    
            * include/debug/safe_iterator.h (_Safe_iterator<>::_Unchecked): New.
            (_Safe_iterator(const _Safe_iterator&, _Unchecked)): New.
            (_Safe_iterator::operator++(int)): Use latter.
            (_Safe_iterator::operator--(int)): Likewise.
            (_Safe_iterator(_Iterator, const _Safe_sequence_base*)): Remove !_M_insular()
            check.
            * include/debug/safe_local_iterator.h (_Safe_local_iterator<>::_Unchecked):
            New.
            (_Safe_local_iterator(const _Safe_local_iterator&, _Unchecked)): New.
            (_Safe_local_iterator::operator++(int)): Use latter.
            * src/c++11/debug.cc (_S_debug_messages): Add as comment the _Debug_msg_id
            entry associated to the array entry.

Diff:
---
 libstdc++-v3/include/debug/safe_iterator.h       | 35 +++++++++++-----
 libstdc++-v3/include/debug/safe_local_iterator.h | 15 ++++---
 libstdc++-v3/src/c++11/debug.cc                  | 53 ++++++++++++++++++++++++
 3 files changed, 87 insertions(+), 16 deletions(-)

diff --git a/libstdc++-v3/include/debug/safe_iterator.h b/libstdc++-v3/include/debug/safe_iterator.h
index f364477a00c..693192b3ea9 100644
--- a/libstdc++-v3/include/debug/safe_iterator.h
+++ b/libstdc++-v3/include/debug/safe_iterator.h
@@ -129,6 +129,12 @@ namespace __gnu_debug
 	typename _Sequence::_Base::iterator,
 	typename _Sequence::_Base::const_iterator>::__type _OtherIterator;
 
+      struct _Unchecked { };
+
+      _Safe_iterator(const _Safe_iterator& __x, _Unchecked) _GLIBCXX_NOEXCEPT
+      : _Iter_base(__x.base()), _Safe_base()
+      { _M_attach(__x._M_sequence); }
+
     public:
       typedef _Iterator					iterator_type;
       typedef typename _Traits::iterator_category	iterator_category;
@@ -154,11 +160,7 @@ namespace __gnu_debug
       _Safe_iterator(_Iterator __i, const _Safe_sequence_base* __seq)
       _GLIBCXX_NOEXCEPT
       : _Iter_base(__i), _Safe_base(__seq, _S_constant())
-      {
-	_GLIBCXX_DEBUG_VERIFY(!this->_M_singular(),
-			      _M_message(__msg_init_singular)
-			      ._M_iterator(*this, "this"));
-      }
+      { }
 
       /**
        * @brief Copy construction.
@@ -339,7 +341,7 @@ namespace __gnu_debug
 	_GLIBCXX_DEBUG_VERIFY(this->_M_incrementable(),
 			      _M_message(__msg_bad_inc)
 			      ._M_iterator(*this, "this"));
-	_Safe_iterator __ret = *this;
+	_Safe_iterator __ret(*this, _Unchecked());
 	++*this;
 	return __ret;
       }
@@ -514,6 +516,13 @@ namespace __gnu_debug
     protected:
       typedef typename _Safe_base::_OtherIterator _OtherIterator;
 
+      typedef typename _Safe_base::_Unchecked _Unchecked;
+
+      _Safe_iterator(const _Safe_iterator& __x,
+		     _Unchecked __unchecked) _GLIBCXX_NOEXCEPT
+	: _Safe_base(__x, __unchecked)
+      { }
+
     public:
       /// @post the iterator is singular and unattached
       _Safe_iterator() _GLIBCXX_NOEXCEPT { }
@@ -596,7 +605,7 @@ namespace __gnu_debug
 	_GLIBCXX_DEBUG_VERIFY(this->_M_incrementable(),
 			      _M_message(__msg_bad_inc)
 			      ._M_iterator(*this, "this"));
-	_Safe_iterator __ret = *this;
+	_Safe_iterator __ret(*this, _Unchecked());
 	++*this;
 	return __ret;
       }
@@ -627,7 +636,7 @@ namespace __gnu_debug
 	_GLIBCXX_DEBUG_VERIFY(this->_M_decrementable(),
 			      _M_message(__msg_bad_dec)
 			      ._M_iterator(*this, "this"));
-	_Safe_iterator __ret = *this;
+	_Safe_iterator __ret(*this, _Unchecked());
 	--*this;
 	return __ret;
       }
@@ -653,6 +662,12 @@ namespace __gnu_debug
       typedef _Safe_iterator<_OtherIterator, _Sequence,
 			     std::random_access_iterator_tag> _OtherSelf;
 
+      typedef typename _Safe_base::_Unchecked _Unchecked;
+      _Safe_iterator(const _Safe_iterator& __x,
+		     _Unchecked __unchecked) _GLIBCXX_NOEXCEPT
+	: _Safe_base(__x, __unchecked)
+      { }
+
     public:
       typedef typename _Safe_base::difference_type	difference_type;
       typedef typename _Safe_base::reference		reference;
@@ -744,7 +759,7 @@ namespace __gnu_debug
 	_GLIBCXX_DEBUG_VERIFY(this->_M_incrementable(),
 			      _M_message(__msg_bad_inc)
 			      ._M_iterator(*this, "this"));
-	_Safe_iterator __ret = *this;
+	_Safe_iterator __ret(*this, _Unchecked());
 	++*this;
 	return __ret;
       }
@@ -771,7 +786,7 @@ namespace __gnu_debug
 	_GLIBCXX_DEBUG_VERIFY(this->_M_decrementable(),
 			      _M_message(__msg_bad_dec)
 			      ._M_iterator(*this, "this"));
-	_Safe_iterator __ret = *this;
+	_Safe_iterator __ret(*this, _Unchecked());
 	--*this;
 	return __ret;
       }
diff --git a/libstdc++-v3/include/debug/safe_local_iterator.h b/libstdc++-v3/include/debug/safe_local_iterator.h
index 624f0ddad0f..d655730c897 100644
--- a/libstdc++-v3/include/debug/safe_local_iterator.h
+++ b/libstdc++-v3/include/debug/safe_local_iterator.h
@@ -84,6 +84,13 @@ namespace __gnu_debug
       typedef _Safe_local_iterator _Self;
       typedef _Safe_local_iterator<_OtherIterator, _Sequence> _OtherSelf;
 
+      struct _Unchecked { };
+
+      _Safe_local_iterator(const _Safe_local_iterator& __x,
+			   _Unchecked) noexcept
+      : _Iter_base(__x.base())
+      { _M_attach(__x._M_sequence); }
+
     public:
       typedef _Iterator					iterator_type;
       typedef typename _Traits::iterator_category	iterator_category;
@@ -104,11 +111,7 @@ namespace __gnu_debug
        */
       _Safe_local_iterator(_Iterator __i, const _Safe_sequence_base* __cont)
       : _Iter_base(__i), _Safe_base(__cont, _S_constant())
-      {
-	_GLIBCXX_DEBUG_VERIFY(!this->_M_singular(),
-			      _M_message(__msg_init_singular)
-			      ._M_iterator(*this, "this"));
-      }
+      { }
 
       /**
        * @brief Copy construction.
@@ -282,7 +285,7 @@ namespace __gnu_debug
 	_GLIBCXX_DEBUG_VERIFY(this->_M_incrementable(),
 			      _M_message(__msg_bad_inc)
 			      ._M_iterator(*this, "this"));
-	_Safe_local_iterator __ret = *this;
+	_Safe_local_iterator __ret(*this, _Unchecked{});
 	++*this;
 	return __ret;
       }
diff --git a/libstdc++-v3/src/c++11/debug.cc b/libstdc++-v3/src/c++11/debug.cc
index d4ee5fa12dc..926e8be6122 100644
--- a/libstdc++-v3/src/c++11/debug.cc
+++ b/libstdc++-v3/src/c++11/debug.cc
@@ -181,86 +181,139 @@ namespace __gnu_debug
   const char* const _S_debug_messages[] =
   {
     // General Checks
+    // __msg_valid_range
     "function requires a valid iterator range [%1.name;, %2.name;)",
+    // __msg_insert_singular
     "attempt to insert into container with a singular iterator",
+    // __msg_insert_different
     "attempt to insert into container with an iterator"
     " from a different container",
+    // __msg_erase_bad
     "attempt to erase from container with a %2.state; iterator",
+    // __msg_erase_different
     "attempt to erase from container with an iterator"
     " from a different container",
+    // __msg_subscript_oob
     "attempt to subscript container with out-of-bounds index %2;,"
     " but container only holds %3; elements",
+    // __msg_empty
     "attempt to access an element in an empty container",
+    // __msg_unpartitioned
     "elements in iterator range [%1.name;, %2.name;)"
     " are not partitioned by the value %3;",
+    // __msg_unpartitioned_pred
     "elements in iterator range [%1.name;, %2.name;)"
     " are not partitioned by the predicate %3; and value %4;",
+    // __msg_unsorted
     "elements in iterator range [%1.name;, %2.name;) are not sorted",
+    // __msg_unsorted_pred
     "elements in iterator range [%1.name;, %2.name;)"
     " are not sorted according to the predicate %3;",
+    // __msg_not_heap
     "elements in iterator range [%1.name;, %2.name;) do not form a heap",
+    // __msg_not_heap_pred
     "elements in iterator range [%1.name;, %2.name;)"
     " do not form a heap with respect to the predicate %3;",
     // std::bitset checks
+    // __msg_bad_bitset_write
     "attempt to write through a singular bitset reference",
+    // __msg_bad_bitset_read
     "attempt to read from a singular bitset reference",
+    // __msg_bad_bitset_flip
     "attempt to flip a singular bitset reference",
     // std::list checks
+    // __msg_self_splice
     "attempt to splice a list into itself",
+    // __msg_splice_alloc
     "attempt to splice lists with unequal allocators",
+    // __msg_splice_bad
     "attempt to splice elements referenced by a %1.state; iterator",
+    // __msg_splice_other
     "attempt to splice an iterator from a different container",
+    // __msg_splice_overlap
     "splice destination %1.name;"
     " occurs within source range [%2.name;, %3.name;)",
     // iterator checks
+    // __msg_init_singular
     "attempt to initialize an iterator that will immediately become singular",
+    // __msg_init_copy_singular
     "attempt to copy-construct an iterator from a singular iterator",
+    // __msg_init_const_singular
     "attempt to construct a constant iterator"
     " from a singular mutable iterator",
+    // __msg_copy_singular
     "attempt to copy from a singular iterator",
+    // __msg_bad_deref
     "attempt to dereference a %1.state; iterator",
+    // __msg_bad_inc
     "attempt to increment a %1.state; iterator",
+    // __msg_bad_dec
     "attempt to decrement a %1.state; iterator",
+    // __msg_iter_subscript_oob
     "attempt to subscript a %1.state; iterator %2; step from"
     " its current position, which falls outside its dereferenceable range",
+    // __msg_advance_oob
     "attempt to advance a %1.state; iterator %2; steps,"
     " which falls outside its valid range",
+    // __msg_retreat_oob
     "attempt to retreat a %1.state; iterator %2; steps,"
     " which falls outside its valid range",
+    // __msg_iter_compare_bad
     "attempt to compare a %1.state; iterator to a %2.state; iterator",
+    // __msg_compare_different
     "attempt to compare iterators from different sequences",
+    // __msg_iter_order_bad
     "attempt to order a %1.state; iterator to a %2.state; iterator",
+    // __msg_order_different
     "attempt to order iterators from different sequences",
+    // __msg_distance_bad
     "attempt to compute the difference between a %1.state;"
     " iterator to a %2.state; iterator",
+    // __msg_distance_different
     "attempt to compute the different between two iterators"
     " from different sequences",
     // istream_iterator
+    // __msg_deref_istream
     "attempt to dereference an end-of-stream istream_iterator",
+    // __msg_inc_istream
     "attempt to increment an end-of-stream istream_iterator",
     // ostream_iterator
+    // __msg_output_ostream
     "attempt to output via an ostream_iterator with no associated stream",
     // istreambuf_iterator
+    // __msg_deref_istreambuf
     "attempt to dereference an end-of-stream istreambuf_iterator"
     " (this is a GNU extension)",
+    // __msg_inc_istreambuf
     "attempt to increment an end-of-stream istreambuf_iterator",
     // std::forward_list
+    // __msg_insert_after_end
     "attempt to insert into container after an end iterator",
+    // __msg_erase_after_bad
     "attempt to erase from container after a %2.state; iterator not followed"
     " by a dereferenceable one",
+    // __msg_valid_range2
     "function requires a valid iterator range (%2.name;, %3.name;)"
     ", \"%2.name;\" shall be before and not equal to \"%3.name;\"",
     // std::unordered_container::local_iterator
+    // __msg_local_iter_compare_bad
     "attempt to compare local iterators from different unordered container"
     " buckets",
+    // __msg_non_empty_range
     "function requires a non-empty iterator range [%1.name;, %2.name;)",
+    // __msg_self_move_assign
     "attempt to self move assign",
+    // __msg_bucket_index_oob
     "attempt to access container with out-of-bounds bucket index %2;,"
     " container only holds %3; buckets",
+    // __msg_valid_load_factor
     "load factor shall be positive",
+    // __msg_equal_allocs
     "allocators must be equal",
+    // __msg_insert_range_from_self
     "attempt to insert with an iterator range [%1.name;, %2.name;) from this"
     " container",
+    // __msg_irreflexive_ordering
     "comparison doesn't meet irreflexive requirements, assert(!(a < a))"
   };