diff -up gambas-3.14.3/gb.db.postgresql/src/main.c.orig gambas-3.14.3/gb.db.postgresql/src/main.c
--- gambas-3.14.3/gb.db.postgresql/src/main.c.orig	2020-06-22 21:31:16.035953348 +0200
+++ gambas-3.14.3/gb.db.postgresql/src/main.c	2020-06-22 21:33:38.812290889 +0200
@@ -33,6 +33,42 @@
 #include <postgres.h>
 #include <pg_type.h>
 
+// Starting v12, PostgreSQL (libpq) redefins printf symbol but the
+// implementation is not exported.
+// This should work-around the issue before a more robust solution is found.
+// PostgreSQL commit that caused this:
+// https://github.com/postgres/postgres/commit/96bf88d5271
+#ifdef vsnprintf
+#undef vsnprintf
+#endif
+#ifdef snprintf
+#undef snprintf
+#endif
+#ifdef vsprintf
+#undef vsprintf
+#endif
+#ifdef sprintf
+#undef sprintf
+#endif
+#ifdef vfprintf
+#undef vfprintf
+#endif
+#ifdef fprintf
+#undef fprintf
+#endif
+#ifdef vprintf
+#undef vprintf
+#endif
+#ifdef printf
+#undef printf
+#endif
+#ifdef strerror
+#undef strerror
+#endif
+#ifdef strerror_r
+#undef strerror_r
+#endif
+
 #ifdef PACKAGE_NAME
 	#undef PACKAGE_NAME
 	#undef PACKAGE_BUGREPORT