--- clang-14.log	2022-11-02 22:36:16.548752395 +1100
+++ clang-15.log	2022-11-02 22:36:16.549752391 +1100
@@ -8,12 +8,17 @@
 
 
 
-./compat/have_strcasestr.c:10:13: warning: call to undeclared function 'strcasestr'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
+./compat/have_strcasestr.c:10:13: error: call to undeclared function 'strcasestr'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
     found = strcasestr (haystack, needle);
             ^
+./compat/have_strcasestr.c:10:13: note: did you mean 'strcasecmp'?
+/usr/include/strings.h:116:12: note: 'strcasecmp' declared here
+extern int strcasecmp (const char *__s1, const char *__s2)
+           ^
 ./compat/have_strcasestr.c:10:11: error: incompatible integer to pointer conversion assigning to 'char *' from 'int' [-Wint-conversion]
     found = strcasestr (haystack, needle);
           ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+2 errors generated.