From 66117f8c593c5041bde9f50f95bfd7a6a0664744 Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Wed, 23 Mar 2022 10:01:00 -0700
Subject: [PATCH v3 1/5] configure: check for dlsym not just dlopen.

When building with sanitizers the sanitizer library provides dlopen, but not
dlsym(), making configure think that -ldl isn't needed.
---
 configure    | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 configure.ac |  3 +++
 2 files changed, 59 insertions(+)

diff --git a/configure b/configure
index f3cb5c2b511..e605f5a17f1 100755
--- a/configure
+++ b/configure
@@ -11912,6 +11912,62 @@ if test "$ac_res" != no; then :
 
 fi
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing dlsym" >&5
+$as_echo_n "checking for library containing dlsym... " >&6; }
+if ${ac_cv_search_dlsym+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_func_search_save_LIBS=$LIBS
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char dlsym ();
+int
+main ()
+{
+return dlsym ();
+  ;
+  return 0;
+}
+_ACEOF
+for ac_lib in '' dl; do
+  if test -z "$ac_lib"; then
+    ac_res="none required"
+  else
+    ac_res=-l$ac_lib
+    LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
+  fi
+  if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_search_dlsym=$ac_res
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext
+  if ${ac_cv_search_dlsym+:} false; then :
+  break
+fi
+done
+if ${ac_cv_search_dlsym+:} false; then :
+
+else
+  ac_cv_search_dlsym=no
+fi
+rm conftest.$ac_ext
+LIBS=$ac_func_search_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_dlsym" >&5
+$as_echo "$ac_cv_search_dlsym" >&6; }
+ac_res=$ac_cv_search_dlsym
+if test "$ac_res" != no; then :
+  test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
+
+fi
+ # Address Sanitizer provides dlopen but not dlsym
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing socket" >&5
 $as_echo_n "checking for library containing socket... " >&6; }
 if ${ac_cv_search_socket+:} false; then :
diff --git a/configure.ac b/configure.ac
index 19d1a803673..b2440e9ae2d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1230,6 +1230,9 @@ AC_SUBST(PTHREAD_LIBS)
 AC_CHECK_LIB(m, main)
 AC_SEARCH_LIBS(setproctitle, util)
 AC_SEARCH_LIBS(dlopen, dl)
+# Address sanitizer's helper library provides dlopen but not dlsym, thus when
+# enabling asan the dlopen check doesn't notice that -ldl is actually required.
+AC_SEARCH_LIBS(dlsym, dl)
 AC_SEARCH_LIBS(socket, [socket ws2_32])
 AC_SEARCH_LIBS(shl_load, dld)
 AC_SEARCH_LIBS(getopt_long, [getopt gnugetopt])
-- 
2.35.1.354.g715d08a9e5