fix constant traicing inside format function when positional placehol…

…der was used

expected/plpgsql_check_active.out

@@ -9257,3 +9257,32 @@ NOTICE:  7
 NOTICE:  8
 NOTICE:  9
 NOTICE:  10
+-- should not raise warning
+create or replace function fx(p text)
+returns void as $$
+begin
+  execute format($_$select '%1$I'$_$, p);
+end;
+$$ language plpgsql;
+-- should be ok
+select * from plpgsql_check_function('fx(text)');
+ plpgsql_check_function 
+------------------------
+(0 rows)
+
+drop function fx(text);
+create or replace function fx()
+returns void as $$
+declare p varchar;
+begin
+  p := 'ahoj';
+  execute format($_$select '%1$I'$_$, p);
+end;
+$$ language plpgsql;
+-- should be ok
+select * from plpgsql_check_function('fx()');
+ plpgsql_check_function 
+------------------------
+(0 rows)
+
+drop function fx();

expected/plpgsql_check_active_1.out

@@ -9260,3 +9260,32 @@ NOTICE:  7
 NOTICE:  8
 NOTICE:  9
 NOTICE:  10
+-- should not raise warning
+create or replace function fx(p text)
+returns void as $$
+begin
+  execute format($_$select '%1$I'$_$, p);
+end;
+$$ language plpgsql;
+-- should be ok
+select * from plpgsql_check_function('fx(text)');
+ plpgsql_check_function 
+------------------------
+(0 rows)
+
+drop function fx(text);
+create or replace function fx()
+returns void as $$
+declare p varchar;
+begin
+  p := 'ahoj';
+  execute format($_$select '%1$I'$_$, p);
+end;
+$$ language plpgsql;
+-- should be ok
+select * from plpgsql_check_function('fx()');
+ plpgsql_check_function 
+------------------------
+(0 rows)
+
+drop function fx();

sql/plpgsql_check_active.sql

@@ -5488,3 +5488,30 @@ begin
   end loop;
 end;
 $$;
+
+-- should not raise warning
+create or replace function fx(p text)
+returns void as $$
+begin
+  execute format($_$select '%1$I'$_$, p);
+end;
+$$ language plpgsql;
+
+-- should be ok
+select * from plpgsql_check_function('fx(text)');
+
+drop function fx(text);
+
+create or replace function fx()
+returns void as $$
+declare p varchar;
+begin
+  p := 'ahoj';
+  execute format($_$select '%1$I'$_$, p);
+end;
+$$ language plpgsql;
+
+-- should be ok
+select * from plpgsql_check_function('fx()');
+
+drop function fx();

src/expr_walk.c

@@ -597,7 +597,7 @@ plpgsql_check_get_formatted_string(PLpgSQL_checkstate *cstate,
 			}
 		}
 
-		_arg = argpos >= 1 ? argpos : arg + 1;
+		_arg = argpos >= 1 ? argpos + 1: arg + 1;
 		if (_arg <= nargs)
 		{
 			char	   *str;