From 171f3374c7668e1e108d5c699ff0ee815967525c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Julian=20M=C3=BCller?= <julian.mueller@uni-konstanz.de>
Date: Thu, 30 Oct 2025 19:52:11 +0100
Subject: [PATCH 1/4] align x64's max stack limit with x86's

---
 stl/inc/regex                                  |  4 ----
 tests/std/tests/VSO_0000000_regex_use/test.cpp | 13 +++++--------
 2 files changed, 5 insertions(+), 12 deletions(-)

diff --git a/stl/inc/regex b/stl/inc/regex
index 2409ce9bd5a..7b5fccb59cb 100644
--- a/stl/inc/regex
+++ b/stl/inc/regex
@@ -48,11 +48,7 @@ _STL_DISABLE_CLANG_WARNINGS
 #endif // !defined(_REGEX_MAX_COMPLEXITY_COUNT)
 
 #ifndef _REGEX_MAX_STACK_COUNT
-#ifdef _WIN64
-#define _REGEX_MAX_STACK_COUNT 600L // set to 0 to disable
-#else // ^^^ defined(_WIN64) / !defined(_WIN64) vvv
 #define _REGEX_MAX_STACK_COUNT 1000L // set to 0 to disable
-#endif // ^^^ !defined(_WIN64) ^^^
 #endif // !defined(_REGEX_MAX_STACK_COUNT)
 
 #ifndef _ENHANCED_REGEX_VISUALIZER
diff --git a/tests/std/tests/VSO_0000000_regex_use/test.cpp b/tests/std/tests/VSO_0000000_regex_use/test.cpp
index 794e3ffd06f..c24d5553024 100644
--- a/tests/std/tests/VSO_0000000_regex_use/test.cpp
+++ b/tests/std/tests/VSO_0000000_regex_use/test.cpp
@@ -910,12 +910,12 @@ void test_gh_997() {
         assert(ex.code() == error_stack);
     }
 
-    wregex rgx(LR"(^http[s]?://([^.]+\.)*example\.com/.*$)", icase);
+    {
+        test_wregex rgx(&g_regexTester, LR"(^http[s]?://([^.]+\.)*example\.com/.*$)", icase);
 
-    assert(regex_match(L"https://www.example.com/meow", rgx));
+        rgx.should_search_match(L"https://www.example.com/meow", L"https://www.example.com/meow");
 
-    try {
-        assert(!regex_match(
+        rgx.should_search_fail(
             L"https://www.bogus.invalid/"
             L"123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789-"
             L"123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789-"
@@ -923,10 +923,7 @@ void test_gh_997() {
             L"123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789-"
             L"123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456.89-123456789-123456789."
             L"123456789-12345678.-123456789-123456789-1.3456789-123456789-123456789-123456789-123456789-123456789-"
-            L"123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789-1234",
-            rgx));
-    } catch (const regex_error& ex) {
-        assert(ex.code() == error_stack);
+            L"123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789-1234");
     }
 }
 

From 699b8fbcef6bb6a0b88f160243de215436e55f80 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Julian=20M=C3=BCller?= <julian.mueller@uni-konstanz.de>
Date: Thu, 30 Oct 2025 19:56:38 +0100
Subject: [PATCH 2/4] remove default arguments from `_Matcher3::_Push_frame()`

---
 stl/inc/regex | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/stl/inc/regex b/stl/inc/regex
index 7b5fccb59cb..ea4447380de 100644
--- a/stl/inc/regex
+++ b/stl/inc/regex
@@ -1810,7 +1810,7 @@ private:
     vector<_Rx_state_frame_t<_It>> _Frames;
     size_t _Frames_count;
 
-    size_t _Push_frame(_Rx_unwind_ops _Code = {}, _Node_base* _Node = nullptr);
+    size_t _Push_frame(_Rx_unwind_ops _Code, _Node_base* _Node);
     void _Pop_frame(size_t);
 
     void _Increase_stack_usage_count();
@@ -3990,7 +3990,7 @@ bool _Matcher3<_BidIt, _Elem, _RxTraits, _It, _Alloc>::_Match_pat(_Node_base* _N
                     auto& _Sav   = _Loop_vals[_Node->_Loop_number];
 
                     if (_Node->_Simple_loop == 1) {
-                        _Sav._Loop_frame_idx = _Push_frame(_Rx_unwind_ops::_Do_nothing);
+                        _Sav._Loop_frame_idx = _Push_frame(_Rx_unwind_ops::_Do_nothing, nullptr);
                         _Increase_complexity_count();
                         if (_Node->_Min > 0 || (_Greedy && !_Longest && _Node->_Max != 0)) { // try a rep first
                             _Sav._Loop_idx = 1;

From c55ceb30e6d624321b9d71154ad5a97cd645f230 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Julian=20M=C3=BCller?= <julian.mueller@uni-konstanz.de>
Date: Thu, 30 Oct 2025 19:59:19 +0100
Subject: [PATCH 3/4] start unwinding opcodes at 1

---
 stl/inc/regex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/stl/inc/regex b/stl/inc/regex
index ea4447380de..b5bddf972b5 100644
--- a/stl/inc/regex
+++ b/stl/inc/regex
@@ -1671,7 +1671,7 @@ public:
 };
 
 enum class _Rx_unwind_ops {
-    _After_assert = _N_end + 1,
+    _After_assert = 1,
     _After_neg_assert,
     _Disjunction_eval_alt_on_failure,
     _Disjunction_eval_alt_always,

From ce3ccf9e14bf726e49d1b536694cc67e7c51ff6a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Julian=20M=C3=BCller?= <julian.mueller@uni-konstanz.de>
Date: Thu, 30 Oct 2025 20:01:16 +0100
Subject: [PATCH 4/4] remove `_Initial_frames_count` from
 `_Matcher3::_Match_pat()`

---
 stl/inc/regex | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/stl/inc/regex b/stl/inc/regex
index b5bddf972b5..489dbf34f42 100644
--- a/stl/inc/regex
+++ b/stl/inc/regex
@@ -3814,8 +3814,7 @@ template <class _BidIt, class _Elem, class _RxTraits, class _It, class _Alloc>
 bool _Matcher3<_BidIt, _Elem, _RxTraits, _It, _Alloc>::_Match_pat(_Node_base* _Nx) { // check for match
     _Increase_stack_usage_count();
 
-    bool _Failed                       = false;
-    const size_t _Initial_frames_count = _Frames_count;
+    bool _Failed = false;
 
     while (_Nx) {
         do { // match current node
@@ -4175,7 +4174,7 @@ bool _Matcher3<_BidIt, _Elem, _RxTraits, _It, _Alloc>::_Match_pat(_Node_base* _N
             }
         } while (_Nx);
 
-        while (_Frames_count > _Initial_frames_count && !_Nx) {
+        while (_Frames_count > 0 && !_Nx) {
             auto& _Frame = _Frames[--_Frames_count];
 
             switch (_Frame._Code) {