conftest.c: In function 'main':
conftest.c:185:1: warning: old-style function definition [-Wold-style-definition]
conftest.c:190:49: warning: passing argument 3 of 'pcre_compile' from incompatible pointer type [-Wincompatible-pointer-types]
  pcre *regexp = pcre_compile("test", PCRE_UTF8, error, error_offset, 0);
                                                 ^~~~~
In file included from conftest.c:182:
/usr/include/pcre.h:540:21: note: expected 'const char **' but argument is of type 'const char *'
 PCRE_EXP_DECL pcre *pcre_compile(const char *, int, const char **, int *,
                     ^~~~~~~~~~~~
conftest.c:190:56: warning: passing argument 4 of 'pcre_compile' makes pointer from integer without a cast [-Wint-conversion]
  pcre *regexp = pcre_compile("test", PCRE_UTF8, error, error_offset, 0);
                                                        ^~~~~~~~~~~~
In file included from conftest.c:182:
/usr/include/pcre.h:540:21: note: expected 'int *' but argument is of type 'int'
 PCRE_EXP_DECL pcre *pcre_compile(const char *, int, const char **, int *,
                     ^~~~~~~~~~~~

conftest.c: In function 'int main()':
conftest.c:192:49: error: cannot convert 'const char*' to 'const char**'
  pcre *regexp = pcre_compile("test", PCRE_UTF8, error, error_offset, 0);
                                                 ^~~~~
In file included from conftest.c:184:
/usr/include/pcre.h:540:53: note:   initializing argument 3 of 'pcre* pcre_compile(const char*, int, const char**, int*, const unsigned char*)'
 PCRE_EXP_DECL pcre *pcre_compile(const char *, int, const char **, int *,
                                                     ^~~~~~~~~~~~~

Index: m4/pcre.m4
===================================================================
--- m4/pcre.m4	(revision 87676)
+++ m4/pcre.m4	(working copy)
@@ -20,7 +20,7 @@
 [
 	const char* error = NULL;
 	int error_offset = -1;
-	pcre *regexp = pcre_compile("test", PCRE_UTF8, error, error_offset, 0);
+	pcre *regexp = pcre_compile("test", PCRE_UTF8, &error, &error_offset, NULL);
 	pcre_free(regexp);
 ],
 found_libpcre="yes")