Fix assorted compiler warnings seen in the buildfarm.

Failure to use DatumGetFoo/FooGetDatum macros correctly, or at all,
causes some warnings about sign conversion.  This is just cosmetic
at the moment but in principle it's a type violation, so clean up
the instances I could find.

autoprewarm.c and sharedfileset.c contained code that unportably
assumed that pid_t is the same size as int.  We've variously dealt
with this by casting pid_t to int or to unsigned long for printing
purposes; I went with the latter.

Fix uninitialized-variable warning in RestoreGUCState.  This is
a live bug in some sense, but of no great significance given that
nobody is very likely to care what "line number" is associated with
a GUC that hasn't got a source file recorded.

src/backend/storage/file/sharedfileset.c

@@ -214,9 +214,9 @@ SharedFileSetPath(char *path, SharedFileSet *fileset, Oid tablespace)
 	char		tempdirpath[MAXPGPATH];
 
 	TempTablespacePath(tempdirpath, tablespace);
-	snprintf(path, MAXPGPATH, "%s/%s%d.%u.sharedfileset",
+	snprintf(path, MAXPGPATH, "%s/%s%lu.%u.sharedfileset",
 			 tempdirpath, PG_TEMP_FILE_PREFIX,
-			 fileset->creator_pid, fileset->number);
+			 (unsigned long) fileset->creator_pid, fileset->number);
 }
 
 /*

src/backend/utils/adt/jsonb.c

@@ -343,6 +343,7 @@ jsonb_in_scalar(void *pstate, char *token, JsonTokenType tokentype)
 {
 	JsonbInState *_state = (JsonbInState *) pstate;
 	JsonbValue	v;
+	Datum		numd;
 
 	switch (tokentype)
 	{
@@ -361,18 +362,19 @@ jsonb_in_scalar(void *pstate, char *token, JsonTokenType tokentype)
 			 */
 			Assert(token != NULL);
 			v.type = jbvNumeric;
-			v.val.numeric = DatumGetNumeric(DirectFunctionCall3(numeric_in, CStringGetDatum(token), 0, -1));
-
+			numd = DirectFunctionCall3(numeric_in,
+									   CStringGetDatum(token),
+									   ObjectIdGetDatum(InvalidOid),
+									   Int32GetDatum(-1));
+			v.val.numeric = DatumGetNumeric(numd);
 			break;
 		case JSON_TOKEN_TRUE:
 			v.type = jbvBool;
 			v.val.boolean = true;
-
 			break;
 		case JSON_TOKEN_FALSE:
 			v.type = jbvBool;
 			v.val.boolean = false;
-
 			break;
 		case JSON_TOKEN_NULL:
 			v.type = jbvNull;
@@ -772,9 +774,14 @@ datum_to_jsonb(Datum val, bool is_null, JsonbInState *result,
 									 strchr(outputstr, 'n') != NULL);
 					if (!numeric_error)
 					{
-						jb.type = jbvNumeric;
-						jb.val.numeric = DatumGetNumeric(DirectFunctionCall3(numeric_in, CStringGetDatum(outputstr), 0, -1));
+						Datum		numd;
 
+						jb.type = jbvNumeric;
+						numd = DirectFunctionCall3(numeric_in,
+												   CStringGetDatum(outputstr),
+												   ObjectIdGetDatum(InvalidOid),
+												   Int32GetDatum(-1));
+						jb.val.numeric = DatumGetNumeric(numd);
 						pfree(outputstr);
 					}
 					else

src/backend/utils/adt/numeric.c

@@ -3818,8 +3818,8 @@ numeric_avg_deserialize(PG_FUNCTION_ARGS)
 	/* sumX */
 	temp = DirectFunctionCall3(numeric_recv,
 							   PointerGetDatum(&buf),
-							   InvalidOid,
-							   -1);
+							   ObjectIdGetDatum(InvalidOid),
+							   Int32GetDatum(-1));
 	init_var_from_num(DatumGetNumeric(temp), &tmp_var);
 	accum_sum_add(&(result->sumX), &tmp_var);
 
@@ -3941,16 +3941,16 @@ numeric_deserialize(PG_FUNCTION_ARGS)
 	/* sumX */
 	temp = DirectFunctionCall3(numeric_recv,
 							   PointerGetDatum(&buf),
-							   InvalidOid,
-							   -1);
+							   ObjectIdGetDatum(InvalidOid),
+							   Int32GetDatum(-1));
 	init_var_from_num(DatumGetNumeric(temp), &sumX_var);
 	accum_sum_add(&(result->sumX), &sumX_var);
 
 	/* sumX2 */
 	temp = DirectFunctionCall3(numeric_recv,
 							   PointerGetDatum(&buf),
-							   InvalidOid,
-							   -1);
+							   ObjectIdGetDatum(InvalidOid),
+							   Int32GetDatum(-1));
 	init_var_from_num(DatumGetNumeric(temp), &sumX2_var);
 	accum_sum_add(&(result->sumX2), &sumX2_var);
 
@@ -4340,14 +4340,14 @@ numeric_poly_deserialize(PG_FUNCTION_ARGS)
 	/* sumX */
 	sumX = DirectFunctionCall3(numeric_recv,
 							   PointerGetDatum(&buf),
-							   InvalidOid,
-							   -1);
+							   ObjectIdGetDatum(InvalidOid),
+							   Int32GetDatum(-1));
 
 	/* sumX2 */
 	sumX2 = DirectFunctionCall3(numeric_recv,
 								PointerGetDatum(&buf),
-								InvalidOid,
-								-1);
+								ObjectIdGetDatum(InvalidOid),
+								Int32GetDatum(-1));
 
 	init_var_from_num(DatumGetNumeric(sumX), &sumX_var);
 #ifdef HAVE_INT128
@@ -4550,8 +4550,8 @@ int8_avg_deserialize(PG_FUNCTION_ARGS)
 	/* sumX */
 	temp = DirectFunctionCall3(numeric_recv,
 							   PointerGetDatum(&buf),
-							   InvalidOid,
-							   -1);
+							   ObjectIdGetDatum(InvalidOid),
+							   Int32GetDatum(-1));
 	init_var_from_num(DatumGetNumeric(temp), &num);
 #ifdef HAVE_INT128
 	numericvar_to_int128(&num, &result->sumX);

src/backend/utils/adt/pgstatfuncs.c

@@ -813,7 +813,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 					 */
 					nulls[12] = true;
 					nulls[13] = true;
-					values[14] = DatumGetInt32(-1);
+					values[14] = Int32GetDatum(-1);
 				}
 				else
 				{

src/backend/utils/misc/guc.c

@@ -9610,6 +9610,8 @@ RestoreGUCState(void *gucstate)
 		if (varsourcefile[0])
 			read_gucstate_binary(&srcptr, srcend,
 								 &varsourceline, sizeof(varsourceline));
+		else
+			varsourceline = 0;
 		read_gucstate_binary(&srcptr, srcend,
 							 &varsource, sizeof(varsource));
 		read_gucstate_binary(&srcptr, srcend,