--- CMakeLists.txt.orig	2023-02-15 10:03:30 UTC
+++ CMakeLists.txt
@@ -96,7 +96,7 @@ include(CheckStructHasMember)
 include(CheckFunctionExists)
 include(CheckSymbolExists)
 include(CheckStructHasMember)
-include(CheckPrototypeDefinition)
+include(CheckPrototypeDefinitionSafe)
 include(AddCFlagIfSupported)
 include(FindPkgLibraries)
 include(FindThreads)
--- cmake/CheckPrototypeDefinitionSafe.cmake.orig	2023-05-14 12:22:20 UTC
+++ cmake/CheckPrototypeDefinitionSafe.cmake
@@ -0,0 +1,16 @@
+include(CheckPrototypeDefinition)
+
+function(check_prototype_definition_safe function prototype return header variable)
+	# temporarily save CMAKE_C_FLAGS and disable warnings about unused
+	# unused functions and parameters, otherwise they will always fail
+	# if ENABLE_WERROR is on
+	set(SAVED_CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
+
+	disable_warnings(unused-function)
+	disable_warnings(unused-parameter)
+
+	check_prototype_definition("${function}" "${prototype}" "${return}" "${header}" "${variable}")
+
+	# restore CMAKE_C_FLAGS
+	set(CMAKE_C_FLAGS "${SAVED_CMAKE_C_FLAGS}")
+endfunction()
--- src/CMakeLists.txt.orig	2023-02-15 10:03:30 UTC
+++ src/CMakeLists.txt
@@ -58,15 +58,29 @@ add_feature_info(futimens GIT_USE_FUTIMENS "futimens s
 
 # qsort
 
-check_prototype_definition(qsort_r
-	"void qsort_r(void *base, size_t nmemb, size_t size, void *thunk, int (*compar)(void *, const void *, const void *))"
-	"" "stdlib.h" GIT_QSORT_R_BSD)
+# old-style FreeBSD qsort_r() has the 'context' parameter as the first argument
+# of the comparison function:
+check_prototype_definition_safe(qsort_r
+	"void (qsort_r)(void *base, size_t nmemb, size_t size, void *context, int (*compar)(void *, const void *, const void *))"
+	"" "stdlib.h" GIT_QSORT_BSD)
 
-check_prototype_definition(qsort_r
-	"void qsort_r(void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *, void *), void *arg)"
-	"" "stdlib.h" GIT_QSORT_R_GNU)
+# GNU or POSIX qsort_r() has the 'context' parameter as the last argument of the
+# comparison function:
+check_prototype_definition_safe(qsort_r
+	"void (qsort_r)(void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *, void *), void *context)"
+	"" "stdlib.h" GIT_QSORT_GNU)
 
-check_function_exists(qsort_s GIT_QSORT_S)
+# C11 qsort_s() has the 'context' parameter as the last argument of the
+# comparison function, and returns an error status:
+check_prototype_definition_safe(qsort_s
+	"errno_t (qsort_s)(void *base, rsize_t nmemb, rsize_t size, int (*compar)(const void *, const void *, void *), void *context)"
+	"0" "stdlib.h" GIT_QSORT_C11)
+
+# MSC qsort_s() has the 'context' parameter as the first argument of the
+# comparison function, and as the last argument of qsort_s():
+check_prototype_definition_safe(qsort_s
+	"void (qsort_s)(void *base, size_t num, size_t width, int (*compare )(void *, const void *, const void *), void *context)"
+	"" "stdlib.h" GIT_QSORT_MSC)
 
 # random / entropy data
 
--- src/features.h.in.orig	2023-02-15 10:03:30 UTC
+++ src/features.h.in
@@ -24,9 +24,10 @@
 #cmakedefine GIT_REGEX_PCRE2
 #cmakedefine GIT_REGEX_BUILTIN 1
 
-#cmakedefine GIT_QSORT_R_BSD
-#cmakedefine GIT_QSORT_R_GNU
-#cmakedefine GIT_QSORT_S
+#cmakedefine GIT_QSORT_BSD
+#cmakedefine GIT_QSORT_GNU
+#cmakedefine GIT_QSORT_C11
+#cmakedefine GIT_QSORT_MSC
 
 #cmakedefine GIT_SSH 1
 #cmakedefine GIT_SSH_MEMORY_CREDENTIALS 1
--- src/util/util.c.orig	2023-02-15 10:03:30 UTC
+++ src/util/util.c
@@ -18,7 +18,7 @@
 # endif
 # include <windows.h>
 
-# ifdef GIT_QSORT_S
+# ifdef GIT_QSORT_MSC
 #  include <search.h>
 # endif
 #endif
@@ -673,7 +673,7 @@ size_t git__unescape(char *str)
 	return (pos - str);
 }
 
-#if defined(GIT_QSORT_S) || defined(GIT_QSORT_R_BSD)
+#if defined(GIT_QSORT_MSC) || defined(GIT_QSORT_BSD)
 typedef struct {
 	git__sort_r_cmp cmp;
 	void *payload;
@@ -688,9 +688,11 @@ static int GIT_LIBGIT2_CALL git__qsort_r_glue_cmp(
 #endif
 
 
-#if !defined(GIT_QSORT_R_BSD) && \
-	!defined(GIT_QSORT_R_GNU) && \
-	!defined(GIT_QSORT_S)
+#if !defined(GIT_QSORT_BSD) && \
+    !defined(GIT_QSORT_GNU) && \
+    !defined(GIT_QSORT_C11) && \
+    !defined(GIT_QSORT_MSC)
+
 static void swap(uint8_t *a, uint8_t *b, size_t elsize)
 {
 	char tmp[256];
@@ -716,17 +718,20 @@ static void insertsort(
 		for (j = i; j > base && cmp(j, j - elsize, payload) < 0; j -= elsize)
 			swap(j, j - elsize, elsize);
 }
+
 #endif
 
 void git__qsort_r(
 	void *els, size_t nel, size_t elsize, git__sort_r_cmp cmp, void *payload)
 {
-#if defined(GIT_QSORT_R_BSD)
+#if defined(GIT_QSORT_GNU)
+	qsort_r(els, nel, elsize, cmp, payload);
+#elif defined(GIT_QSORT_C11)
+	qsort_s(els, nel, elsize, cmp, payload);
+#elif defined(GIT_QSORT_BSD)
 	git__qsort_r_glue glue = { cmp, payload };
 	qsort_r(els, nel, elsize, &glue, git__qsort_r_glue_cmp);
-#elif defined(GIT_QSORT_R_GNU)
-	qsort_r(els, nel, elsize, cmp, payload);
-#elif defined(GIT_QSORT_S)
+#elif defined(GIT_QSORT_MSC)
 	git__qsort_r_glue glue = { cmp, payload };
 	qsort_s(els, nel, elsize, git__qsort_r_glue_cmp, &glue);
 #else