libstdc++: Fix allocator propagation in regex algorithms [PR107376]

The PR points out that we assume the match_results allocator is default
constuctible, which might not be true. We also have a related issue with
unwanted propagation from an object that might have an unequal
allocator.

Ideally we use the same allocator type for _State_info::_M_match_queue
but that would be an ABI change now. We should investigate if that can
be done without breaking anything, which might be possible because the
_Executor object is short-lived and never leaks out of the regex_match,
regex_search, and regex_replace algorithms. If we change the mangled
name for _Executor then there would be no ODR violations when mixing old
and new definitions. This commit does not attempt that.

libstdc++-v3/ChangeLog:

	PR libstdc++/107376
	* include/bits/regex_executor.h (_Executor::_Executor): Use same
	allocator for _M_cur_results and _M_results.
	* include/bits/regex_executor.tcc (_Executor::_M_main_dispatch):
	Prevent possibly incorrect allocator propagating to
	_M_cur_results.
	* testsuite/28_regex/algorithms/regex_match/107376.cc: New test.

diff --git a/libstdc++-v3/include/bits/regex_executor.h b/libstdc++-v3/include/bits/regex_executor.h
index dc0878ce678703d37a8a5ca233372a908d50098c..cdafcd5523d55ae3a935a59cb9eca6df4c0854fc 100644 (file)
--- a/libstdc++-v3/include/bits/regex_executor.h
+++ b/libstdc++-v3/include/bits/regex_executor.h
@@ -71,14 +71,15 @@ namespace __detail
                _ResultsVec&    __results,
                const _RegexT&  __re,
                _FlagT          __flags)
-      : _M_begin(__begin),
-      _M_end(__end),
-      _M_re(__re),
-      _M_nfa(*__re._M_automaton),
-      _M_results(__results),
-      _M_rep_count(_M_nfa.size()),
-      _M_states(_M_nfa._M_start(), _M_nfa.size()),
-      _M_flags(__flags)
+      : _M_cur_results(__results.get_allocator()),
+       _M_begin(__begin),
+       _M_end(__end),
+       _M_re(__re),
+       _M_nfa(*__re._M_automaton),
+       _M_results(__results),
+       _M_rep_count(_M_nfa.size()),
+       _M_states(_M_nfa._M_start(), _M_nfa.size()),
+       _M_flags(__flags)
       {
        using namespace regex_constants;
        if (__flags & match_prev_avail) // ignore not_bol and not_bow

diff --git a/libstdc++-v3/include/bits/regex_executor.tcc b/libstdc++-v3/include/bits/regex_executor.tcc
index b93e958075e3d3266ae01b8dd1ffca8f41d67d4e..a5885ed34badd0da4c8779dd71b49eff191fb04f 100644 (file)
--- a/libstdc++-v3/include/bits/regex_executor.tcc
+++ b/libstdc++-v3/include/bits/regex_executor.tcc
@@ -124,9 +124,10 @@ namespace __detail
            break;
          std::fill_n(_M_states._M_visited_states, _M_nfa.size(), false);
          auto __old_queue = std::move(_M_states._M_match_queue);
+         auto __alloc = _M_cur_results.get_allocator();
          for (auto& __task : __old_queue)
            {
-             _M_cur_results = std::move(__task.second);
+             _M_cur_results = _ResultsVec(std::move(__task.second), __alloc);
              _M_dfs(__match_mode, __task.first);
            }
          if (__match_mode == _Match_mode::_Prefix)

diff --git a/libstdc++-v3/testsuite/28_regex/algorithms/regex_match/107376.cc b/libstdc++-v3/testsuite/28_regex/algorithms/regex_match/107376.cc
new file mode 100644 (file)
index 0000000..da4f7ad
--- /dev/null
+++ b/libstdc++-v3/testsuite/28_regex/algorithms/regex_match/107376.cc
@@ -0,0 +1,76 @@
+// { dg-do run { target c++11 } }
+#include <regex>
+#include <testsuite_hooks.h>
+#include <testsuite_allocator.h>
+
+template<typename T>
+struct Alloc
+{
+  using value_type = T;
+  explicit Alloc(int) { }
+  template<typename U> Alloc(const Alloc&) { }
+
+  T* allocate(std::size_t n)
+  { return std::allocator<T>().allocate(n); }
+  void deallocate(T* ptr, std::size_t n)
+  { std::allocator<T>().deallocate(ptr, n); }
+
+  bool operator==(const Alloc&) const { return true; }
+  bool operator!=(const Alloc&) const { return false; }
+};
+
+void
+test_non_default_constructible()
+{
+  using sub_match = std::sub_match<const char*>;
+  using alloc_type = Alloc<sub_match>;
+  using match_results = std::match_results<const char*, alloc_type>;
+  match_results res(alloc_type(1));
+
+  std::regex_match("x", res, std::regex(".")); // PR libstdc++/107376
+}
+
+template<typename T>
+struct PropAlloc
+{
+  int id;
+
+  using value_type = T;
+  explicit PropAlloc(int id) : id(id) { }
+  template<typename U> PropAlloc(const PropAlloc& a) : id(a.id) { }
+
+  using propagate_on_container_move_assignment = std::true_type;
+  using propagate_on_container_copy_assignment = std::true_type;
+
+  PropAlloc select_on_container_copy_construction() const
+  { return PropAlloc(0); }
+
+  T* allocate(std::size_t n)
+  { return std::allocator<T>().allocate(n); }
+  void deallocate(T* ptr, std::size_t n)
+  { std::allocator<T>().deallocate(ptr, n); }
+
+  bool operator==(const PropAlloc& a) const { return id == a.id; }
+  bool operator!=(const PropAlloc& a) const { return id != a.id; }
+};
+
+void
+test_propagation()
+{
+  using sub_match = std::sub_match<const char*>;
+  using alloc_type = PropAlloc<sub_match>;
+  using match_results = std::match_results<const char*, alloc_type>;
+  alloc_type alloc(107376);
+  match_results res(alloc);
+
+  std::regex re("..", std::regex_constants::__polynomial);
+  std::regex_match("xx", res, re);
+
+  VERIFY( res.get_allocator() == alloc );
+}
+
+int main()
+{
+  test_non_default_constructible();
+  test_propagation();
+}