diff --git a/stl/inc/regex b/stl/inc/regex
index aa1974d47e1..05cb7465d3b 100644
--- a/stl/inc/regex
+++ b/stl/inc/regex
@@ -58,7 +58,7 @@ _STL_DISABLE_CLANG_WARNINGS
 
 _STD_BEGIN
 
-enum _Meta_type { // meta character representations for parser
+enum _Meta_type : int { // meta character representations for parser
     _Meta_lpar  = '(',
     _Meta_rpar  = ')',
     _Meta_dlr   = '$',
diff --git a/stl/inc/sstream b/stl/inc/sstream
index 365753b94e0..12a90ae5651 100644
--- a/stl/inc/sstream
+++ b/stl/inc/sstream
@@ -67,12 +67,12 @@ public:
         const basic_string<_Elem, _Traits, _Alloc2>& _Str, ios_base::openmode _Mode = ios_base::in | ios_base::out)
         : basic_stringbuf(_Str, _Mode, _Alloc{}) {}
 
-    basic_stringbuf(basic_stringbuf&& _Right, const _Alloc& _Al_) : _Al(_Al_) {
+    basic_stringbuf(basic_stringbuf&& _Right, const _Alloc& _Al_) : _Mystate(0), _Al(_Al_) {
         _Assign_rv(_STD move(_Right));
     }
 #endif // _HAS_CXX20
 
-    basic_stringbuf(basic_stringbuf&& _Right) {
+    basic_stringbuf(basic_stringbuf&& _Right) : _Mystate(0) {
         _Assign_rv(_STD move(_Right));
     }
 
@@ -269,7 +269,7 @@ protected:
 
         _Mysb::setp(_Newptr, _New_pnext, _Newptr + _Newsize);
         if (_Mystate & _Noread) { // maintain eback() == allocated pointer invariant
-            _Mysb::setg(_Newptr, nullptr, _Newptr);
+            _Mysb::setg(_Newptr, _Newptr, _Newptr);
         } else { // if readable, set the get area to initialized region
             _Mysb::setg(_Newptr, _Newptr + (_Mysb::gptr() - _Oldptr), _Seekhigh);
         }
@@ -328,6 +328,12 @@ protected:
 
     pos_type seekoff(
         off_type _Off, ios_base::seekdir _Way, ios_base::openmode _Mode = ios_base::in | ios_base::out) override {
+        const bool _Need_read_but_cannot  = (_Mode & ios_base::in) != 0 && (_Mystate & _Noread) != 0;
+        const bool _Need_write_but_cannot = (_Mode & ios_base::out) != 0 && (_Mystate & _Constant) != 0;
+        if (_Need_read_but_cannot || _Need_write_but_cannot) {
+            return pos_type{off_type{-1}};
+        }
+
         // change position by _Off, according to _Way, _Mode
         const auto _Gptr_old = _Mysb::gptr();
         const auto _Pptr_old = (_Mystate & _Constant) ? nullptr : _Mysb::pptr();
@@ -388,6 +394,12 @@ protected:
     }
 
     pos_type seekpos(pos_type _Pos, ios_base::openmode _Mode = ios_base::in | ios_base::out) override {
+        const bool _Need_read_but_cannot  = (_Mode & ios_base::in) != 0 && (_Mystate & _Noread) != 0;
+        const bool _Need_write_but_cannot = (_Mode & ios_base::out) != 0 && (_Mystate & _Constant) != 0;
+        if (_Need_read_but_cannot || _Need_write_but_cannot) {
+            return pos_type{off_type{-1}};
+        }
+
         // change position to _Pos, according to _Mode
         const auto _Off      = static_cast<streamoff>(_Pos);
         const auto _Gptr_old = _Mysb::gptr();
@@ -440,7 +452,7 @@ protected:
                 _Mysb::setp(_Pnew, (_State & (_Atend | _Append)) ? _Seekhigh : _Pnew, _Seekhigh);
 
                 if (_State & _Noread) { // maintain "_Allocated == eback() points to buffer base" invariant
-                    _Mysb::setg(_Pnew, nullptr, _Pnew);
+                    _Mysb::setg(_Pnew, _Pnew, _Pnew);
                 }
             }
 
@@ -469,7 +481,7 @@ protected:
 
         _Mysb::setp(_Pnew, _Next, _End_buffer);
         if (_State & _Noread) { // maintain "_Allocated == eback() points to buffer base" invariant
-            _Mysb::setg(_Pnew, nullptr, _Pnew);
+            _Mysb::setg(_Pnew, _Pnew, _Pnew);
         } else {
             _Mysb::setg(_Pnew, _Pnew, _Seekhigh);
         }
diff --git a/tests/std/tests/char8_t_17_matrix.lst b/tests/std/tests/char8_t_17_matrix.lst
index 97170842230..cfabb7ae85e 100644
--- a/tests/std/tests/char8_t_17_matrix.lst
+++ b/tests/std/tests/char8_t_17_matrix.lst
@@ -35,3 +35,4 @@ PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsin
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MDd /std:c++17"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++20 /permissive-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MTd /std:c++latest /permissive- /fp:strict"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++latest /permissive- /fp:strict -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/std/tests/char8_t_impure_matrix.lst b/tests/std/tests/char8_t_impure_matrix.lst
index d5a87b4e2c3..f7c9462651c 100644
--- a/tests/std/tests/char8_t_impure_matrix.lst
+++ b/tests/std/tests/char8_t_impure_matrix.lst
@@ -37,3 +37,4 @@ PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsin
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MDd /std:c++17"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++20 /permissive-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MTd /std:c++latest /permissive- /fp:strict"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++latest /permissive- /fp:strict -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/std/tests/char8_t_matrix.lst b/tests/std/tests/char8_t_matrix.lst
index 12d002c7609..7795932f132 100644
--- a/tests/std/tests/char8_t_matrix.lst
+++ b/tests/std/tests/char8_t_matrix.lst
@@ -36,3 +36,4 @@ PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsin
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MDd /std:c++17 /w14640 /Zc:threadSafeInit-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++20 /permissive- /w14640 /Zc:threadSafeInit-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MTd /std:c++latest /permissive- /fp:strict /w14640 /Zc:threadSafeInit-"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++latest /permissive- /fp:strict /w14640 /Zc:threadSafeInit- -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/std/tests/concepts_20_matrix.lst b/tests/std/tests/concepts_20_matrix.lst
index 7ce5f2b0e0c..ea8806b97bb 100644
--- a/tests/std/tests/concepts_20_matrix.lst
+++ b/tests/std/tests/concepts_20_matrix.lst
@@ -27,3 +27,4 @@ PM_CL="/clr /MDd /std:c++20"
 # PM_CL="/std:c++latest /permissive- /BE /c /EHsc /MTd"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /std:c++20 /permissive- /MD"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /std:c++latest /permissive- /MTd /fp:strict"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /std:c++latest /permissive- /MT /fp:strict -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/std/tests/concepts_latest_matrix.lst b/tests/std/tests/concepts_latest_matrix.lst
index 73625bbbb86..ecf410ca036 100644
--- a/tests/std/tests/concepts_latest_matrix.lst
+++ b/tests/std/tests/concepts_latest_matrix.lst
@@ -22,3 +22,4 @@ PM_CL="/MTd /D_ITERATOR_DEBUG_LEVEL=2 /permissive- /analyze:only /analyze:autolo
 # PM_CL="/permissive- /BE /c /MTd"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /permissive- /MD"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /permissive- /MTd /fp:strict"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /permissive- /MT /fp:strict -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/std/tests/impure_matrix.lst b/tests/std/tests/impure_matrix.lst
index 53e8bf46f1c..a14eb162d57 100644
--- a/tests/std/tests/impure_matrix.lst
+++ b/tests/std/tests/impure_matrix.lst
@@ -35,3 +35,4 @@ PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsin
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MDd /std:c++17"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++20 /permissive-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MTd /std:c++latest /permissive- /fp:strict"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++latest /permissive- /fp:strict -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/std/tests/locale0_implib_cpp_matrix.lst b/tests/std/tests/locale0_implib_cpp_matrix.lst
index 32992138ddc..73891267e7c 100644
--- a/tests/std/tests/locale0_implib_cpp_matrix.lst
+++ b/tests/std/tests/locale0_implib_cpp_matrix.lst
@@ -37,3 +37,4 @@ PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsin
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MDd /std:c++17 /w14640 /Zc:threadSafeInit-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++20 /permissive- /w14640 /Zc:threadSafeInit-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MTd /std:c++latest /permissive- /fp:strict /w14640 /Zc:threadSafeInit-"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++latest /permissive- /fp:strict /w14640 /Zc:threadSafeInit- -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/std/tests/strict_concepts_20_matrix.lst b/tests/std/tests/strict_concepts_20_matrix.lst
index e8dd503d44f..cc86671e318 100644
--- a/tests/std/tests/strict_concepts_20_matrix.lst
+++ b/tests/std/tests/strict_concepts_20_matrix.lst
@@ -26,3 +26,4 @@ PM_CL="/clr /MDd /std:c++20"
 # PM_CL="/std:c++latest /BE /c /EHsc /MTd"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /std:c++20 /MD"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /std:c++latest /MTd /fp:strict"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /std:c++latest /MT /fp:strict -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/std/tests/strict_concepts_latest_matrix.lst b/tests/std/tests/strict_concepts_latest_matrix.lst
index 3b126ab4c16..2604c0e479c 100644
--- a/tests/std/tests/strict_concepts_latest_matrix.lst
+++ b/tests/std/tests/strict_concepts_latest_matrix.lst
@@ -24,3 +24,4 @@ PM_CL="/MTd /D_ITERATOR_DEBUG_LEVEL=2 /analyze:only /analyze:autolog-"
 # PM_CL="/BE /c /MTd"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /MD"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /MTd /fp:strict"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /MT /fp:strict -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/std/tests/usual_17_matrix.lst b/tests/std/tests/usual_17_matrix.lst
index 510cc46a999..6b82f8ba838 100644
--- a/tests/std/tests/usual_17_matrix.lst
+++ b/tests/std/tests/usual_17_matrix.lst
@@ -34,3 +34,4 @@ PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsin
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MDd /std:c++17"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++20 /permissive-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MTd /std:c++latest /permissive- /fp:strict"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++latest /permissive- /fp:strict -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/std/tests/usual_20_matrix.lst b/tests/std/tests/usual_20_matrix.lst
index c8aa8e8da23..119e24c2246 100644
--- a/tests/std/tests/usual_20_matrix.lst
+++ b/tests/std/tests/usual_20_matrix.lst
@@ -24,3 +24,4 @@ PM_CL="/BE /c /EHsc /MD /std:c++20 /permissive-"
 PM_CL="/BE /c /EHsc /MTd /std:c++latest /permissive-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /std:c++20 /permissive- /MD"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /std:c++latest /permissive- /MTd /fp:strict"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /std:c++latest /permissive- /MT /fp:strict -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/std/tests/usual_latest_matrix.lst b/tests/std/tests/usual_latest_matrix.lst
index 0f50c36029c..68e6e2fbcae 100644
--- a/tests/std/tests/usual_latest_matrix.lst
+++ b/tests/std/tests/usual_latest_matrix.lst
@@ -22,3 +22,4 @@ PM_CL="/BE /c /MD /permissive-"
 PM_CL="/BE /c /MTd /permissive-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /permissive- /MD"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /permissive- /MTd /fp:strict"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /permissive- /MT /fp:strict -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/std/tests/usual_matrix.lst b/tests/std/tests/usual_matrix.lst
index bde343a864b..ecf7265160b 100644
--- a/tests/std/tests/usual_matrix.lst
+++ b/tests/std/tests/usual_matrix.lst
@@ -36,3 +36,4 @@ PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsin
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MDd /std:c++17 /w14640 /Zc:threadSafeInit-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++20 /permissive- /w14640 /Zc:threadSafeInit-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MTd /std:c++latest /permissive- /fp:strict /w14640 /Zc:threadSafeInit-"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++latest /permissive- /fp:strict /w14640 /Zc:threadSafeInit- -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/tr1/env.lst b/tests/tr1/env.lst
index a6afa08fef3..a814774a4a5 100644
--- a/tests/tr1/env.lst
+++ b/tests/tr1/env.lst
@@ -31,3 +31,4 @@ PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsin
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call -Wno-deprecated-declarations -Wno-self-assign /EHsc /MDd /std:c++17"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call -Wno-deprecated-declarations -Wno-self-assign /EHsc /MT /std:c++20 /permissive-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call -Wno-deprecated-declarations -Wno-self-assign /EHsc /MTd /std:c++latest /permissive-"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call -Wno-deprecated-declarations -Wno-self-assign /EHsc /MT /std:c++latest /permissive- -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/tr1/env_minus_md_idl.lst b/tests/tr1/env_minus_md_idl.lst
index d9f860c1dbf..2fc8c1b4a5d 100644
--- a/tests/tr1/env_minus_md_idl.lst
+++ b/tests/tr1/env_minus_md_idl.lst
@@ -26,3 +26,4 @@ PM_CL="/BE /c /EHsc /MTd /std:c++latest /permissive- /w14640 /Zc:threadSafeInit-
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call -Wno-deprecated-declarations -Wno-self-assign /EHsc /MD /std:c++14 /w14640 /Zc:threadSafeInit-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call -Wno-deprecated-declarations -Wno-self-assign /EHsc /MDd /std:c++17 /w14640 /Zc:threadSafeInit-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call -Wno-deprecated-declarations -Wno-self-assign /EHsc /MTd /std:c++latest /permissive- /w14640 /Zc:threadSafeInit-"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call -Wno-deprecated-declarations -Wno-self-assign /EHsc /MT /std:c++latest /permissive- /w14640 /Zc:threadSafeInit- -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/tr1/env_minus_pure.lst b/tests/tr1/env_minus_pure.lst
index fee56896524..72ffa04557e 100644
--- a/tests/tr1/env_minus_pure.lst
+++ b/tests/tr1/env_minus_pure.lst
@@ -27,3 +27,4 @@ PM_CL="/BE /c /EHsc /MTd /std:c++latest /permissive-"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call -Wno-deprecated-declarations -Wno-self-assign /EHsc /MD /std:c++14"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call -Wno-deprecated-declarations -Wno-self-assign /EHsc /MDd /std:c++17"
 PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call -Wno-deprecated-declarations -Wno-self-assign /EHsc /MTd /std:c++latest /permissive-"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call -Wno-deprecated-declarations -Wno-self-assign /EHsc /MT /std:c++latest /permissive- -fsanitize=undefined -fno-sanitize-recover=undefined"
diff --git a/tests/tr1/tests/chrono/test.cpp b/tests/tr1/tests/chrono/test.cpp
index d02fa73132b..635a66a4be0 100644
--- a/tests/tr1/tests/chrono/test.cpp
+++ b/tests/tr1/tests/chrono/test.cpp
@@ -53,9 +53,9 @@ namespace {
         CHECK_INT(d_i::max(), STD numeric_limits<int>::max());
 
         typedef STD chrono::duration_values<double> d_d;
-        CHECK_INT(d_d::zero(), 0.0);
-        CHECK_INT(d_d::min(), STD numeric_limits<double>::lowest());
-        CHECK_INT(d_d::max(), STD numeric_limits<double>::max());
+        CHECK_DOUBLE(d_d::zero(), 0.0);
+        CHECK_DOUBLE(d_d::min(), STD numeric_limits<double>::lowest());
+        CHECK_DOUBLE(d_d::max(), STD numeric_limits<double>::max());
     }
 
     template <class Rep, class Period>
diff --git a/tests/tr1/tests/cstddef/test.cpp b/tests/tr1/tests/cstddef/test.cpp
index c8731270d76..e0d4c158f69 100644
--- a/tests/tr1/tests/cstddef/test.cpp
+++ b/tests/tr1/tests/cstddef/test.cpp
@@ -20,16 +20,14 @@ typedef struct {
 } Str;
 
 void test_cpp() { // test C++ header
-    ptrdiff_t zero                  = 0;
-    static char* pc                 = (char*) zero;
     static const STDx size_t offs[] = {offsetof(Str, f1), offsetof(Str, f2), offsetof(Str, f3)};
-    STDx ptrdiff_t pdiff            = &pc[INT_MAX] - &pc[0];
+    STDx ptrdiff_t pdiff            = &offs[2] - &offs[0];
     wchar_t wc                      = L'Z';
     Str x                           = {1, {2}, 3};
     char* ps                        = (char*) &x;
 
     CHECK_INT(sizeof(STDx size_t), sizeof(sizeof(char)));
-    CHECK_INT(pdiff, &pc[INT_MAX] - &pc[0]);
+    CHECK_INT(pdiff, &offs[2] - &offs[0]);
     CHECK_INT(wc, L'Z');
     CHECK(offs[0] < offs[1]);
     CHECK_INT((long) *(float*) (ps + offs[1]), 2);
diff --git a/tests/tr1/tests/streambuf1/test.cpp b/tests/tr1/tests/streambuf1/test.cpp
index ea455177770..78dedcea08e 100644
--- a/tests/tr1/tests/streambuf1/test.cpp
+++ b/tests/tr1/tests/streambuf1/test.cpp
@@ -28,7 +28,7 @@ class Mybuf : public STD streambuf {
     }
 
     void setp(char* p) { // set pptr
-        Mybase::setp(p, nullptr);
+        Mybase::setp(p, p);
     }
 
     char* getp() const { // get pptr
diff --git a/tests/tr1/tests/streambuf2/test.cpp b/tests/tr1/tests/streambuf2/test.cpp
index 12d7202f466..991adeca90f 100644
--- a/tests/tr1/tests/streambuf2/test.cpp
+++ b/tests/tr1/tests/streambuf2/test.cpp
@@ -29,7 +29,7 @@ class Mybuf : public STD wstreambuf {
     }
 
     void setp(wchar_t* p) { // set pptr
-        Mybase::setp(p, nullptr);
+        Mybase::setp(p, p);
     }
 
     wchar_t* getp() const { // get pptr
diff --git a/tests/tr1/tests/type_traits5/test.cpp b/tests/tr1/tests/type_traits5/test.cpp
index 9cdf0005555..e0ef94e1d3d 100644
--- a/tests/tr1/tests/type_traits5/test.cpp
+++ b/tests/tr1/tests/type_traits5/test.cpp
@@ -180,7 +180,7 @@ static void t_add_rvalue_reference() { // test add_rvalue_reference<T> for vario
     CHECK_TYPEX(STD add_rvalue_reference<ARR1>::type, ARR1 &&);
 }
 
-typedef enum { red, blue, green } color;
+enum color : int { red, blue, green };
 
 static void t_make_signed() { // test make_signed<T> for various types
     CHECK_TYPE(STD make_signed<signed char>::type, signed char);
diff --git a/tests/utils/stl/test/features.py b/tests/utils/stl/test/features.py
index abfa20bbc62..5a8adf8e64c 100644
--- a/tests/utils/stl/test/features.py
+++ b/tests/utils/stl/test/features.py
@@ -49,6 +49,7 @@ def getDefaultFeatures(config, litConfig):
         DEFAULT_FEATURES.append(Feature(name='x86'))
 
     elif litConfig.target_arch.casefold() == 'x64'.casefold():
+        DEFAULT_FEATURES.append(Feature(name='ubsan'))
         DEFAULT_FEATURES.append(Feature(name='edg'))
         DEFAULT_FEATURES.append(Feature(name='arch_avx2'))
         DEFAULT_FEATURES.append(Feature(name='x64'))
diff --git a/tests/utils/stl/test/tests.py b/tests/utils/stl/test/tests.py
index 09fdeb86fc2..5d10ae30386 100644
--- a/tests/utils/stl/test/tests.py
+++ b/tests/utils/stl/test/tests.py
@@ -249,8 +249,10 @@ def _parseFlags(self, litConfig):
                 self.requires.append('clr_pure') # TRANSITION, GH-798
             elif flag[1:] == 'clr':
                 self.requires.append('clr') # TRANSITION, GH-797
+            elif flag[1:] == 'fsanitize=undefined':
+                self.requires.append('ubsan') # available for x64, see features.py
             elif flag[1:] == 'BE':
-                self.requires.append('edg') # available for x86, see features.py
+                self.requires.append('edg') # available for x64, see features.py
             elif flag[1:] == 'arch:AVX2':
                 self.requires.append('arch_avx2') # available for x86 and x64, see features.py
             elif flag[1:] == 'arch:IA32':