diff --git a/stl/inc/xcall_once.h b/stl/inc/xcall_once.h
index 5057ca65d18..8874e232f81 100644
--- a/stl/inc/xcall_once.h
+++ b/stl/inc/xcall_once.h
@@ -40,8 +40,7 @@ union _Immortalizer_impl { // constructs _Ty, never destroys
     _Ty _Storage;
 };
 
-#if defined(_M_CEE) || defined(_M_ARM64EC) || defined(_M_HYBRID) \
-    || defined(__clang__) // TRANSITION, Clang doesn't recognize /ALTERNATENAME, not yet reported
+#if defined(_M_CEE) || defined(_M_ARM64EC) || defined(_M_HYBRID)
 #define _WINDOWS_API              __stdcall
 #define _RENAME_WINDOWS_API(_Api) _Api##_clr
 #else // ^^^ use forwarders / use /ALTERNATENAME vvv
diff --git a/tests/std/tests/GH_002030_asan_annotate_string/env.lst b/tests/std/tests/GH_002030_asan_annotate_string/env.lst
index f1dd40a650d..08acc3dc792 100644
--- a/tests/std/tests/GH_002030_asan_annotate_string/env.lst
+++ b/tests/std/tests/GH_002030_asan_annotate_string/env.lst
@@ -1,57 +1,40 @@
 # Copyright (c) Microsoft Corporation.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-# This test matrix is the usual test matrix, with all currently unsupported options removed, crossed with the ASan flags.
+# This test matrix is the usual test matrix, with all currently unsupported options removed, with
+# some additional /Zc:char8_t coverage, crossed with the ASan flags.
 
 # TRANSITION, google/sanitizers#328: clang-cl does not support /MDd or /MTd with ASan
 RUNALL_INCLUDE ..\prefix.lst
 RUNALL_CROSSLIST
 PM_CL="/Zi /wd4611 /w14640 /Zc:threadSafeInit-" PM_LINK="/debug"
 RUNALL_CROSSLIST
-PM_CL="-fsanitize=address /BE /c /EHsc /MD /std:c++14"
-PM_CL="-fsanitize=address /BE /c /EHsc /MDd /std:c++17 /permissive-"
-PM_CL="-fsanitize=address /BE /c /EHsc /MT /std:c++20 /permissive-"
-PM_CL="-fsanitize=address /BE /c /EHsc /MTd /std:c++latest /permissive-"
-PM_CL="-fsanitize=address /EHsc /MD /std:c++14"
-PM_CL="-fsanitize=address /EHsc /MD /std:c++17"
-PM_CL="-fsanitize=address /EHsc /MD /std:c++20"
-PM_CL="-fsanitize=address /EHsc /MD /std:c++latest /permissive- /Zc:char8_t- /Zc:preprocessor"
-PM_CL="-fsanitize=address /EHsc /MD /std:c++latest /permissive- /Zc:noexceptTypes-"
-PM_CL="-fsanitize=address /EHsc /MDd /std:c++14 /fp:except /Zc:preprocessor"
-PM_CL="-fsanitize=address /EHsc /MDd /std:c++17 /permissive-"
-PM_CL="-fsanitize=address /EHsc /MDd /std:c++20 /permissive-"
-PM_CL="-fsanitize=address /EHsc /MDd /std:c++latest /permissive- /Zc:wchar_t-"
-PM_CL="-fsanitize=address /EHsc /MDd /std:c++latest /permissive-"
-PM_CL="-fsanitize=address /EHsc /MT /std:c++latest /permissive- /analyze:only /analyze:autolog-"
-PM_CL="-fsanitize=address /EHsc /MT /std:c++latest /permissive-"
-PM_CL="-fsanitize=address /EHsc /MTd /std:c++latest /permissive"
-PM_CL="-fsanitize=address /EHsc /MTd /std:c++latest /permissive- /analyze:only /analyze:autolog-"
-PM_CL="-fsanitize=address /EHsc /MTd /std:c++latest /permissive- /fp:strict"
-PM_CL="-fsanitize=address /EHsc /MTd /std:c++latest /permissive-"
-PM_CL="/D_ANNOTATE_STRING /BE /c /EHsc /MD /std:c++14"
-PM_CL="/D_ANNOTATE_STRING /BE /c /EHsc /MDd /std:c++17 /permissive-"
-PM_CL="/D_ANNOTATE_STRING /BE /c /EHsc /MT /std:c++20 /permissive-"
-PM_CL="/D_ANNOTATE_STRING /BE /c /EHsc /MTd /std:c++latest /permissive-"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MD /std:c++14"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MD /std:c++14 /Zc:char8_t"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MD /std:c++17"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MD /std:c++17 /Zc:char8_t"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MD /std:c++20"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MD /std:c++latest /permissive- /Zc:char8_t- /Zc:preprocessor"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MD /std:c++latest /permissive- /Zc:noexceptTypes-"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MDd /std:c++14 /fp:except /Zc:preprocessor"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MDd /std:c++17 /permissive-"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MDd /std:c++20 /permissive-"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MDd /std:c++latest /permissive- /Zc:wchar_t-"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MDd /std:c++latest /permissive-"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MT /std:c++latest /permissive- /analyze:only /analyze:autolog-"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MT /std:c++latest /permissive-"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MTd /std:c++latest /permissive"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MTd /std:c++latest /permissive- /analyze:only /analyze:autolog-"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MTd /std:c++latest /permissive- /fp:strict"
-PM_CL="/D_ANNOTATE_STRING /EHsc /MTd /std:c++latest /permissive-"
-# TRANSITION, clang-cl does not support /alternatename so we cannot test /D_ANNOTATE_STRING without -fsanitize=address
-PM_COMPILER="clang-cl" PM_CL="-fsanitize=address -fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MD /std:c++14"
-PM_COMPILER="clang-cl" PM_CL="-fsanitize=address -fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MD /std:c++17"
-PM_COMPILER="clang-cl" PM_CL="-fsanitize=address -fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++20 /permissive-"
-PM_COMPILER="clang-cl" PM_CL="-fsanitize=address -fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++latest /permissive- /fp:strict"
+PM_CL="-fsanitize=address"
+PM_CL="/D_ANNOTATE_STRING"
+RUNALL_CROSSLIST
+PM_CL="/BE /c /EHsc /MD /std:c++14"
+PM_CL="/BE /c /EHsc /MDd /std:c++17 /permissive-"
+PM_CL="/BE /c /EHsc /MT /std:c++20 /permissive-"
+PM_CL="/BE /c /EHsc /MTd /std:c++latest /permissive-"
+PM_CL="/EHsc /MD /std:c++14"
+PM_CL="/EHsc /MD /std:c++14 /Zc:char8_t"
+PM_CL="/EHsc /MD /std:c++17"
+PM_CL="/EHsc /MD /std:c++17 /Zc:char8_t"
+PM_CL="/EHsc /MD /std:c++20"
+PM_CL="/EHsc /MD /std:c++latest /permissive- /Zc:char8_t- /Zc:preprocessor"
+PM_CL="/EHsc /MD /std:c++latest /permissive- /Zc:noexceptTypes-"
+PM_CL="/EHsc /MDd /std:c++14 /fp:except /Zc:preprocessor"
+PM_CL="/EHsc /MDd /std:c++17 /permissive-"
+PM_CL="/EHsc /MDd /std:c++20 /permissive-"
+PM_CL="/EHsc /MDd /std:c++latest /permissive- /Zc:wchar_t-"
+PM_CL="/EHsc /MDd /std:c++latest /permissive-"
+PM_CL="/EHsc /MT /std:c++latest /permissive- /analyze:only /analyze:autolog-"
+PM_CL="/EHsc /MT /std:c++latest /permissive-"
+PM_CL="/EHsc /MTd /std:c++latest /permissive"
+PM_CL="/EHsc /MTd /std:c++latest /permissive- /analyze:only /analyze:autolog-"
+PM_CL="/EHsc /MTd /std:c++latest /permissive- /fp:strict"
+PM_CL="/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 /MD /std:c++14"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MD /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 /MT /std:c++latest /permissive- /fp:strict"
diff --git a/tests/std/tests/GH_002030_asan_annotate_vector/env.lst b/tests/std/tests/GH_002030_asan_annotate_vector/env.lst
index 1e9c4211833..4182c344a2e 100644
--- a/tests/std/tests/GH_002030_asan_annotate_vector/env.lst
+++ b/tests/std/tests/GH_002030_asan_annotate_vector/env.lst
@@ -8,48 +8,30 @@ RUNALL_INCLUDE ..\prefix.lst
 RUNALL_CROSSLIST
 PM_CL="/Zi /wd4611 /w14640 /Zc:threadSafeInit-" PM_LINK="/debug"
 RUNALL_CROSSLIST
-PM_CL="-fsanitize=address /BE /c /EHsc /MD /std:c++14"
-PM_CL="-fsanitize=address /BE /c /EHsc /MDd /std:c++17 /permissive-"
-PM_CL="-fsanitize=address /BE /c /EHsc /MT /std:c++20 /permissive-"
-PM_CL="-fsanitize=address /BE /c /EHsc /MTd /std:c++latest /permissive-"
-PM_CL="-fsanitize=address /EHsc /MD /std:c++14"
-PM_CL="-fsanitize=address /EHsc /MD /std:c++17"
-PM_CL="-fsanitize=address /EHsc /MD /std:c++20"
-PM_CL="-fsanitize=address /EHsc /MD /std:c++latest /permissive- /Zc:char8_t- /Zc:preprocessor"
-PM_CL="-fsanitize=address /EHsc /MD /std:c++latest /permissive- /Zc:noexceptTypes-"
-PM_CL="-fsanitize=address /EHsc /MDd /std:c++14 /fp:except /Zc:preprocessor"
-PM_CL="-fsanitize=address /EHsc /MDd /std:c++17 /permissive-"
-PM_CL="-fsanitize=address /EHsc /MDd /std:c++20 /permissive-"
-PM_CL="-fsanitize=address /EHsc /MDd /std:c++latest /permissive- /Zc:wchar_t-"
-PM_CL="-fsanitize=address /EHsc /MDd /std:c++latest /permissive-"
-PM_CL="-fsanitize=address /EHsc /MT /std:c++latest /permissive- /analyze:only /analyze:autolog-"
-PM_CL="-fsanitize=address /EHsc /MT /std:c++latest /permissive-"
-PM_CL="-fsanitize=address /EHsc /MTd /std:c++latest /permissive"
-PM_CL="-fsanitize=address /EHsc /MTd /std:c++latest /permissive- /analyze:only /analyze:autolog-"
-PM_CL="-fsanitize=address /EHsc /MTd /std:c++latest /permissive- /fp:strict"
-PM_CL="-fsanitize=address /EHsc /MTd /std:c++latest /permissive-"
-PM_CL="/D_ANNOTATE_VECTOR /BE /c /EHsc /MD /std:c++14"
-PM_CL="/D_ANNOTATE_VECTOR /BE /c /EHsc /MDd /std:c++17 /permissive-"
-PM_CL="/D_ANNOTATE_VECTOR /BE /c /EHsc /MT /std:c++20 /permissive-"
-PM_CL="/D_ANNOTATE_VECTOR /BE /c /EHsc /MTd /std:c++latest /permissive-"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MD /std:c++14"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MD /std:c++17"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MD /std:c++20"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MD /std:c++latest /permissive- /Zc:char8_t- /Zc:preprocessor"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MD /std:c++latest /permissive- /Zc:noexceptTypes-"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MDd /std:c++14 /fp:except /Zc:preprocessor"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MDd /std:c++17 /permissive-"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MDd /std:c++20 /permissive-"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MDd /std:c++latest /permissive- /Zc:wchar_t-"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MDd /std:c++latest /permissive-"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MT /std:c++latest /permissive- /analyze:only /analyze:autolog-"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MT /std:c++latest /permissive-"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MTd /std:c++latest /permissive"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MTd /std:c++latest /permissive- /analyze:only /analyze:autolog-"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MTd /std:c++latest /permissive- /fp:strict"
-PM_CL="/D_ANNOTATE_VECTOR /EHsc /MTd /std:c++latest /permissive-"
-# TRANSITION, clang-cl does not support /alternatename so we cannot test /D_ANNOTATE_VECTOR without -fsanitize=address
-PM_COMPILER="clang-cl" PM_CL="-fsanitize=address -fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MD /std:c++14"
-PM_COMPILER="clang-cl" PM_CL="-fsanitize=address -fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MD /std:c++17"
-PM_COMPILER="clang-cl" PM_CL="-fsanitize=address -fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++20 /permissive-"
-PM_COMPILER="clang-cl" PM_CL="-fsanitize=address -fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MT /std:c++latest /permissive- /fp:strict"
+PM_CL="-fsanitize=address"
+PM_CL="/D_ANNOTATE_VECTOR"
+RUNALL_CROSSLIST
+PM_CL="/BE /c /EHsc /MD /std:c++14"
+PM_CL="/BE /c /EHsc /MDd /std:c++17 /permissive-"
+PM_CL="/BE /c /EHsc /MT /std:c++20 /permissive-"
+PM_CL="/BE /c /EHsc /MTd /std:c++latest /permissive-"
+PM_CL="/EHsc /MD /std:c++14"
+PM_CL="/EHsc /MD /std:c++17"
+PM_CL="/EHsc /MD /std:c++20"
+PM_CL="/EHsc /MD /std:c++latest /permissive- /Zc:char8_t- /Zc:preprocessor"
+PM_CL="/EHsc /MD /std:c++latest /permissive- /Zc:noexceptTypes-"
+PM_CL="/EHsc /MDd /std:c++14 /fp:except /Zc:preprocessor"
+PM_CL="/EHsc /MDd /std:c++17 /permissive-"
+PM_CL="/EHsc /MDd /std:c++20 /permissive-"
+PM_CL="/EHsc /MDd /std:c++latest /permissive- /Zc:wchar_t-"
+PM_CL="/EHsc /MDd /std:c++latest /permissive-"
+PM_CL="/EHsc /MT /std:c++latest /permissive- /analyze:only /analyze:autolog-"
+PM_CL="/EHsc /MT /std:c++latest /permissive-"
+PM_CL="/EHsc /MTd /std:c++latest /permissive"
+PM_CL="/EHsc /MTd /std:c++latest /permissive- /analyze:only /analyze:autolog-"
+PM_CL="/EHsc /MTd /std:c++latest /permissive- /fp:strict"
+PM_CL="/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 /MD /std:c++14"
+PM_COMPILER="clang-cl" PM_CL="-fno-ms-compatibility -fno-delayed-template-parsing -Wno-unqualified-std-cast-call /EHsc /MD /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 /MT /std:c++latest /permissive- /fp:strict"