* libstdc++-v3/include/bits/regex.h (regex_iterator::regex_iterator()):

	Define end() as _M_pregex == nullptr.
	* libstdc++-v3/include/bits/regex.tcc (regex_iterator::operator==(),
	regex_iterator::operator++()): Fix operator==() and operator++() to
	look at null-ness of _M_pregex on both sides.
	* testsuite/28_regex/regression.cc: New testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@242025 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 22 insertions, 0 deletions

diff --git a/libstdc++-v3/testsuite/28_regex/regression.cc b/libstdc++-v3/testsuite/28_regex/regression.cc
index effb356075e..5214fe3dbc2 100644
--- a/libstdc++-v3/testsuite/28_regex/regression.cc
+++ b/libstdc++-v3/testsuite/28_regex/regression.cc
@@ -72,6 +72,27 @@ test05()
   VERIFY(regex_match_debug("-", std::regex("[a-]")));
 }
 
+// PR libstdc++/78236
+void
+test06()
+{
+  char const s[] = "afoo";
+  std::basic_regex<char> r("(f+)");
+  {
+    std::cregex_iterator i(s, s+sizeof(s), r);
+    std::cregex_iterator j(s, s+sizeof(s), r);
+    VERIFY(i == j);
+  }
+  // The iterator manipulation code must be repeated in the same scope
+  // to expose the undefined read during the execution of the ==
+  // operator (stack location reuse)
+  {
+    std::cregex_iterator i(s, s+sizeof(s), r);
+    std::cregex_iterator j;
+    VERIFY(!(i == j));
+  }
+}
+
 int
 main()
 {
@@ -80,6 +101,7 @@ main()
   test03();
   test04();
   test05();
+  test06();
   return 0;
 }