diff --git a/contrib/extprotocol/gpextprotocol.c b/contrib/extprotocol/gpextprotocol.c
index fcb1294f8ce..aa11f5034b1 100644
--- a/contrib/extprotocol/gpextprotocol.c
+++ b/contrib/extprotocol/gpextprotocol.c
@@ -288,7 +288,7 @@ DemoUri *ParseDemoUri(const char *uri_str)
 	/*
 	 * parse protocol
 	 */
-	char *post_protocol = strstr(uri_str, "://");
+	const char *post_protocol = strstr(uri_str, "://");
 		
 	if(!post_protocol)
 	{
diff --git a/src/backend/access/external/url_curl.c b/src/backend/access/external/url_curl.c
index 8fdca1e5e1a..11fe7ccc4c3 100644
--- a/src/backend/access/external/url_curl.c
+++ b/src/backend/access/external/url_curl.c
@@ -1524,7 +1524,7 @@ url_curl_fopen(char *url, bool forwrite, extvar_t *ev, CopyState pstate)
 	{
 		/* use empty message */
 		CURL_EASY_SETOPT(file->curl->handle, CURLOPT_POSTFIELDS, "");
-		CURL_EASY_SETOPT(file->curl->handle, CURLOPT_POSTFIELDSIZE, 0);
+		CURL_EASY_SETOPT(file->curl->handle, CURLOPT_POSTFIELDSIZE, 0L);
 
 		/* post away and check response, retry if failed (timeout or * connect error) */
 		gp_perform_backoff_and_check_response(file, easy_perform_work);
@@ -2015,7 +2015,7 @@ gp_proto0_write_done(URL_CURL_FILE *file)
 
 	/* use empty message */
 	CURL_EASY_SETOPT(file->curl->handle, CURLOPT_POSTFIELDS, "");
-	CURL_EASY_SETOPT(file->curl->handle, CURLOPT_POSTFIELDSIZE, 0);
+	CURL_EASY_SETOPT(file->curl->handle, CURLOPT_POSTFIELDSIZE, 0L);
 
 	/* post away! */
 	gp_perform_backoff_and_check_response(file, easy_perform_work);
diff --git a/src/backend/cdb/cdbmutate.c b/src/backend/cdb/cdbmutate.c
index ef61404b27a..a920892693e 100644
--- a/src/backend/cdb/cdbmutate.c
+++ b/src/backend/cdb/cdbmutate.c
@@ -1641,6 +1641,14 @@ typedef struct ctid_inventory_context
 	Index		relid;
 } ctid_inventory_context;
 
+static bool
+ctid_inventory_walker(Node *node, ctid_inventory_context *inv);
+static bool
+ctid_inventory_walker_adapter(Node *node, void *inv)
+{
+	return ctid_inventory_walker(node, (ctid_inventory_context *) inv);
+}
+
 static bool
 ctid_inventory_walker(Node *node, ctid_inventory_context *inv)
 {
@@ -2724,6 +2732,14 @@ typedef struct ParamWalkerContext
 	Bitmapset  *scanrelids;		/* Bitmapset for scanrelid */
 } ParamWalkerContext;
 
+static bool
+param_walker(Node *node, ParamWalkerContext *context);
+static bool
+param_walker_adapter(Node *node, void *context)
+{
+	return param_walker(node, (ParamWalkerContext *) context);
+}
+
 static bool
 param_walker(Node *node, ParamWalkerContext *context)
 {
@@ -2817,6 +2833,14 @@ rte_param_walker(List *rtable, ParamWalkerContext *context)
 	}
 }
 
+static bool
+initplan_walker(Node *node, ParamWalkerContext *context);
+static bool
+initplan_walker_adapter(Node *node, void *context)
+{
+	return initplan_walker(node, (ParamWalkerContext *) context);
+}
+
 static bool
 initplan_walker(Node *node, ParamWalkerContext *context)
 {
diff --git a/src/backend/cdb/cdbplan.c b/src/backend/cdb/cdbplan.c
index abb4b99b36b..4afe5d1c765 100644
--- a/src/backend/cdb/cdbplan.c
+++ b/src/backend/cdb/cdbplan.c
@@ -933,7 +933,7 @@ plan_tree_mutator(Node *node,
  *
  */
 static void
-mutate_plan_fields(Plan *newplan, Plan *oldplan, Node *(*mutator) (), void *context)
+mutate_plan_fields(Plan *newplan, Plan *oldplan, Node *(*mutator) (Node *, void *), void *context)
 {
 	/*
 	 * Scalar fields startup_cost total_cost plan_rows plan_width nParamExec
diff --git a/src/backend/cdb/dispatcher/cdbgang.c b/src/backend/cdb/dispatcher/cdbgang.c
index c992af0bddd..1e1a3d5ed3d 100644
--- a/src/backend/cdb/dispatcher/cdbgang.c
+++ b/src/backend/cdb/dispatcher/cdbgang.c
@@ -158,7 +158,7 @@ AllocateGang(CdbDispatcherState *ds, GangType type, List *segments)
 bool
 segment_failure_due_to_recovery(const char *error_message)
 {
-	char	   *fatal = NULL,
+	const char	   *fatal = NULL,
 			   *ptr = NULL;
 	int			fatal_len = 0;
 
@@ -201,7 +201,7 @@ segment_failure_due_to_recovery(const char *error_message)
 bool
 segment_failure_due_to_missing_writer(const char *error_message)
 {
-	char	   *fatal = NULL,
+	const char	   *fatal = NULL,
 			   *ptr = NULL;
 	int			fatal_len = 0;
 
@@ -223,7 +223,7 @@ segment_failure_due_to_missing_writer(const char *error_message)
 bool
 segment_failure_due_to_fault_injector(const char *error_message)
 {
-	char	   *fatal = NULL,
+	const char	   *fatal = NULL,
 			   *ptr = NULL;
 	int			fatal_len = 0;
 
diff --git a/src/backend/commands/resgroupcmds.c b/src/backend/commands/resgroupcmds.c
index 750e1da71a0..36fdb0ab3fc 100644
--- a/src/backend/commands/resgroupcmds.c
+++ b/src/backend/commands/resgroupcmds.c
@@ -1625,8 +1625,8 @@ checkCpusetSyntax(const char *cpuset)
 extern void
 checkCpuSetByRole(const char *cpuset)
 {
-	char *first = NULL;
-	char *last = NULL;
+	const char *first = NULL;
+	const char *last = NULL;
 
 	if (cpuset == NULL)
 	{
diff --git a/src/backend/executor/execUtils.c b/src/backend/executor/execUtils.c
index 1e000112371..6ae9d162f8e 100644
--- a/src/backend/executor/execUtils.c
+++ b/src/backend/executor/execUtils.c
@@ -2407,6 +2407,15 @@ typedef struct MotionFinderContext
 /*
  * Walker to find a motion node that matches a particular motionID
  */
+static bool
+MotionFinderWalker(Plan *node,
+				  void *context);
+static bool
+MotionFinderWalker_adapter(Node *node, void *context)
+{
+	return MotionFinderWalker((Plan *) node, context);
+}
+
 static bool
 MotionFinderWalker(Plan *node,
 				  void *context)
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 98eefd64e89..0bac03a34a0 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -2869,6 +2869,11 @@ cdb_extract_plan_dependencies(PlannerInfo *root, Plan *plan)
 	(void) cdb_extract_plan_dependencies_walker((Node *) plan, &context);
 }
 
+static bool
+cdb_extract_plan_dependencies_walker(Node *node, cdb_extract_plan_dependencies_context *context);
+static bool
+cdb_extract_plan_dependencies_walker_adapter(Node *node, void *context);
+
 static bool
 cdb_extract_plan_dependencies_walker(Node *node, cdb_extract_plan_dependencies_context *context)
 {
diff --git a/src/backend/optimizer/util/predtest_valueset.c b/src/backend/optimizer/util/predtest_valueset.c
index f5c55ef3c2e..e8387c9d82b 100644
--- a/src/backend/optimizer/util/predtest_valueset.c
+++ b/src/backend/optimizer/util/predtest_valueset.c
@@ -28,7 +28,7 @@
 #define INT32MAX (2147483647)
 #define INT32MIN (-2147483648)
 
-static HTAB *CreateNodeSetHashTable();
+static HTAB *CreateNodeSetHashTable(MemoryContext memoryContext);
 static void AddValue(PossibleValueSet *pvs, Const *valueToCopy);
 static void RemoveValue(PossibleValueSet *pvs, Const *value);
 static bool ContainsValue(PossibleValueSet *pvs, Const *value);
diff --git a/src/backend/optimizer/util/walkers.c b/src/backend/optimizer/util/walkers.c
index 6110e9cdfe5..0c038a5e7a1 100644
--- a/src/backend/optimizer/util/walkers.c
+++ b/src/backend/optimizer/util/walkers.c
@@ -29,8 +29,8 @@ void exec_init_plan_tree_base(plan_tree_base_prefix *base, PlannedStmt *stmt)
 	base->node = (Node*)stmt;
 }
 
-static bool walk_scan_node_fields(Scan *scan, bool (*walker) (), void *context);
-static bool walk_join_node_fields(Join *join, bool (*walker) (), void *context);
+static bool walk_scan_node_fields(Scan *scan, bool (*walker) (Node *, void *), void *context);
+static bool walk_join_node_fields(Join *join, bool (*walker) (Node *, void *), void *context);
 
 
 /* ----------------------------------------------------------------------- *
@@ -50,7 +50,7 @@ static bool walk_join_node_fields(Join *join, bool (*walker) (), void *context);
  */
 bool
 walk_plan_node_fields(Plan *plan,
-					  bool (*walker) (),
+					  bool (*walker) (Node *, void *),
 					  void *context)
 {
 	/* target list to be computed at this node */
@@ -94,7 +94,7 @@ walk_plan_node_fields(Plan *plan,
  */
 bool
 walk_scan_node_fields(Scan *scan,
-					  bool (*walker) (),
+					  bool (*walker) (Node *, void *),
 					  void *context)
 {
 	/* A Scan node is a kind of Plan node. */
@@ -119,7 +119,7 @@ walk_scan_node_fields(Scan *scan,
  */
 bool
 walk_join_node_fields(Join *join,
-					  bool (*walker) (),
+					  bool (*walker) (Node *, void *),
 					  void *context)
 {
 	/* A Join node is a kind of Plan node. */
@@ -637,6 +637,11 @@ List *extract_nodes_plan(Plan *pl, int nodeTag, bool descendIntoSubqueries)
 	return context.nodes;
 }
 
+static bool
+extract_nodes_walker(Node *node, extract_context *context);
+static bool
+extract_nodes_walker_adapter(Node *node, void *context);
+
 static bool
 extract_nodes_walker(Node *node, extract_context *context)
 {
diff --git a/src/backend/utils/misc/fstream/fstream.c b/src/backend/utils/misc/fstream/fstream.c
index a789c9bdc92..d315e7bd5c7 100644
--- a/src/backend/utils/misc/fstream/fstream.c
+++ b/src/backend/utils/misc/fstream/fstream.c
@@ -380,7 +380,7 @@ static int glob_path(fstream_t *fs, const char *path)
 		while (*path == ' ')
 			path++;
 
-		p = strchr(path, ' ');
+		p = (char *)strchr(path, ' ');
 
 		if (p)
 			*p++ = 0;
diff --git a/src/backend/utils/misc/uriparser.c b/src/backend/utils/misc/uriparser.c
index 9d4213771f0..1874a3437c3 100644
--- a/src/backend/utils/misc/uriparser.c
+++ b/src/backend/utils/misc/uriparser.c
@@ -70,7 +70,7 @@ ParseExternalTableUri(const char *uri_str)
 
 	else /* not recognized. treat it as a custom protocol */
 	{
-		char *post_protocol = strstr(uri_str, "://");
+		const char *post_protocol = strstr(uri_str, "://");
 		
 		if(!post_protocol)
 		{
diff --git a/src/backend/utils/resource_manager/memquota.c b/src/backend/utils/resource_manager/memquota.c
index b05a403eed3..f865abe396f 100644
--- a/src/backend/utils/resource_manager/memquota.c
+++ b/src/backend/utils/resource_manager/memquota.c
@@ -338,6 +338,16 @@ IsRootOperatorInGroup(Node *node)
  * in a plan.
  */
 
+static bool PolicyAutoPrelimWalker(Node *node, PolicyAutoContext *context);
+static bool PolicyAutoAssignWalker(Node *node, PolicyAutoContext *context);
+static bool PolicyEagerFreePrelimWalker(Node *node, PolicyEagerFreeContext *context);
+static bool PolicyEagerFreeAssignWalker(Node *node, PolicyEagerFreeContext *context);
+
+static bool PolicyAutoPrelimWalker_adapter(Node *node, void *context);
+static bool PolicyAutoAssignWalker_adapter(Node *node, void *context);
+static bool PolicyEagerFreePrelimWalker_adapter(Node *node, void *context);
+static bool PolicyEagerFreeAssignWalker_adapter(Node *node, void *context);
+
 static bool PolicyAutoPrelimWalker(Node *node, PolicyAutoContext *context)
 {
 	if (node == NULL)
@@ -893,6 +903,30 @@ PolicyEagerFreeAssignWalker(Node *node, PolicyEagerFreeContext *context)
 	return result;
 }
 
+static bool
+PolicyAutoPrelimWalker_adapter(Node *node, void *context)
+{
+	return PolicyAutoPrelimWalker(node, (PolicyAutoContext *) context);
+}
+
+static bool
+PolicyAutoAssignWalker_adapter(Node *node, void *context)
+{
+	return PolicyAutoAssignWalker(node, (PolicyAutoContext *) context);
+}
+
+static bool
+PolicyEagerFreePrelimWalker_adapter(Node *node, void *context)
+{
+	return PolicyEagerFreePrelimWalker(node, (PolicyEagerFreeContext *) context);
+}
+
+static bool
+PolicyEagerFreeAssignWalker_adapter(Node *node, void *context)
+{
+	return PolicyEagerFreeAssignWalker(node, (PolicyEagerFreeContext *) context);
+}
+
 /*
  * PolicyEagerFreeAssignOperatorMemoryKB
  *    Main entry point for memory quota OPTIMIZE. This function distributes the memory
diff --git a/src/test/regress/pg_regress.c b/src/test/regress/pg_regress.c
index e095a1fae52..99b86a0f628 100644
--- a/src/test/regress/pg_regress.c
+++ b/src/test/regress/pg_regress.c
@@ -1053,8 +1053,8 @@ const char *
 get_expectfile(const char *testname, const char *file, const char *default_expectfile)
 {
 	char		expectpath[MAXPGPATH];
-	char	   *file_type;
-	char	   *file_name;
+	const char	   *file_type;
+	const char	   *file_name;
 	char		base_file[MAXPGPATH];
 	_resultmap *rm;
 	char		buf[MAXPGPATH];
@@ -1085,7 +1085,7 @@ get_expectfile(const char *testname, const char *file, const char *default_expec
 	 * up to the last slash.
 	 */
 	{
-		char	   *p = strrchr(default_expectfile, '/');
+		const char	   *p = strrchr(default_expectfile, '/');
 
 		if (!p)
 			return NULL;
diff --git a/src/timezone/zic.c b/src/timezone/zic.c
index 0a0fc49f670..741051eda98 100644
--- a/src/timezone/zic.c
+++ b/src/timezone/zic.c
@@ -2606,7 +2606,7 @@ doabbr(char *abbr, struct zone const *zp, char const *letters,
 	   bool isdst, zic_t save, bool doquotes)
 {
 	char	   *cp;
-	char	   *slashp;
+	const char	   *slashp;
 	size_t		len;
 	char const *format = zp->z_format;