dMZX Forums: -Wunused-result -> Archived MegaZeux Bugs -> Tracker

Linux glibc seems to have added the warn_unused_result attribute to every library function call they possibly could have. While our ignoring these return values doesn't do a lot of harm, these warnings should be legitimately fixed as much as possible (i.e. no hacks).

It is possible to add -Wno-unused-result to the cflags for GCC >= 4.6, but I'd rather fix these properly.

2018-10-05 edit: updated remaining instances.

util.c

src/util.c: In function ‘mzx_res_init’:
src/util.c:139:5: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
     chdir(bin_path);
     ^~~~~~~~~~~~~~~
src/util.c:140:5: warning: ignoring return value of ‘getcwd’, declared with attribute warn_unused_result [-Wunused-result]
     getcwd(bin_path, MAX_PATH);
     ^~~~~~~~~~~~~~~~~~~~~~~~~~
src/util.c:166:7: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
       chdir(CONFDIR);
       ^~~~~~~~~~~~~~
src/util.c:168:7: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
       chdir(SHAREDIR);
       ^~~~~~~~~~~~~~~
src/util.c:170:5: warning: ignoring return value of ‘getcwd’, declared with attribute warn_unused_result [-Wunused-result]
     getcwd(p_dir, MAX_PATH);
     ^~~~~~~~~~~~~~~~~~~~~~~
src/util.c:200:7: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
       chdir(bin_path);
       ^~~~~~~~~~~~~~~

window.c

src/window.c: In function ‘file_manager’:
src/window.c:2761:3: warning: ignoring return value of ‘getcwd’, declared with attribute warn_unused_result [-Wunused-result]
   getcwd(return_dir_name, MAX_PATH);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/window.c:2786:5: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
     chdir(current_dir_name);
     ^~~~~~~~~~~~~~~~~~~~~~~
src/window.c:2851:19: warning: ignoring return value of ‘fread’, declared with attribute warn_unused_result [-Wunused-result]
                   fread(file_list[num_files] + 30, 1, 24, mzx_file);
                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/window.c:2895:5: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
     chdir(return_dir_name);
     ^~~~~~~~~~~~~~~~~~~~~~
src/window.c: In function ‘remove_files’:
src/window.c:2670:3: warning: ignoring return value of ‘getcwd’, declared with attribute warn_unused_result [-Wunused-result]
   getcwd(current_dir_name, MAX_PATH);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/window.c:2671:3: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
   chdir(directory_name);
   ^~~~~~~~~~~~~~~~~~~~~
src/window.c:2695:3: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
   chdir(current_dir_name);
   ^~~~~~~~~~~~~~~~~~~~~~~

world.c

src/world.c: In function ‘reload_world’:
src/world.c:3052:5: warning: ignoring return value of ‘getcwd’, declared with attribute warn_unused_result [-Wunused-result]
     getcwd(current_dir, MAX_PATH);
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/world.c: In function ‘load_world’:
src/world.c:2510:5: warning: ignoring return value of ‘getcwd’, declared with attribute warn_unused_result [-Wunused-result]
     getcwd(current_dir, MAX_PATH);
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/world.c:2513:7: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
       chdir(file_path);
       ^~~~~~~~~~~~~~~~
src/world.c: In function ‘reload_swap’:
src/world.c:3116:3: warning: ignoring return value of ‘getcwd’, declared with attribute warn_unused_result [-Wunused-result]
   getcwd(full_path, MAX_PATH);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~

main.c

 
src/main.c: In function ‘main’:
src/main.c:90:3: warning: ignoring return value of ‘getcwd’, declared with attribute warn_unused_result [-Wunused-result]
   getcwd(current_dir, MAX_PATH);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/main.c:121:3: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
   chdir(config_dir);
   ^~~~~~~~~~~~~~~~~
src/main.c:136:3: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
   chdir(current_dir);
   ^~~~~~~~~~~~~~~~~~
src/main.c:152:3: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
   chdir(current_dir);
   ^~~~~~~~~~~~~~~~~~

edit.c

src/editor/edit.c: In function ‘__edit_world’:
src/editor/edit.c:3447:3: warning: ignoring return value of ‘getcwd’, declared with attribute warn_unused_result [-Wunused-result]
   getcwd(editor->current_listening_dir, MAX_PATH);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/editor/edit.c: In function ‘editor_key’:
src/editor/edit.c:2767:13: warning: ignoring return value of ‘getcwd’, declared with attribute warn_unused_result [-Wunused-result]
             getcwd(current_dir, MAX_PATH);
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/editor/edit.c:2768:13: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
             chdir(editor->current_listening_dir);
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/editor/edit.c:2779:13: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
             chdir(current_dir);
             ^~~~~~~~~~~~~~~~~~
src/editor/edit.c:2983:15: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
               chdir(new_path);
               ^~~~~~~~~~~~~~~
src/editor/edit.c:3014:11: warning: ignoring return value of ‘getcwd’, declared with attribute warn_unused_result [-Wunused-result]
           getcwd(editor->test_reload_dir, MAX_PATH);
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/editor/edit.c: In function ‘editor_resume’:
src/editor/edit.c:3348:5: warning: ignoring return value of ‘chdir’, declared with attribute warn_unused_result [-Wunused-result]
     chdir(editor->test_reload_dir);
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fixed the warnings in the utils.

src/utils/txt2hlp.c: In function ‘main’:
src/utils/txt2hlp.c:154:9: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result]
         fscanf(source, "%3d", &link);
         ^
src/utils/checkres.c: In function ‘load_file’:
src/utils/checkres.c:1463:3: warning: ignoring return value of ‘fread’, declared with attribute warn_unused_result [-Wunused-result]
   fread(buffer, *buf_size, 1, fp);
   ^

Warnings from graphics.c should be fixed as of 08b5f56.

src/graphics.c: In function ‘ec_load_set_secondary’:
src/graphics.c:184:3: warning: ignoring return value of ‘fread’, declared with attribute warn_unused_result [-Wunused-result]
   fread(dest, CHAR_SIZE, CHARSET_SIZE, fp);
   ^
src/graphics.c: In function ‘ec_load_set_var’:
src/graphics.c:209:3: warning: ignoring return value of ‘fread’, declared with attribute warn_unused_result [-Wunused-result]
   fread(graphics.charset + (pos * CHAR_SIZE), CHAR_SIZE, size, fp);
   ^

Fixed most instances that don't involve chdir or getcwd in GIT a4ebe25 and GIT 6faf4ba. The sole exception is an fread in window.c used to grab world names in the file manager.

Updating status to: Fixed
Updating version to: 2.90d
Issue fixed in: 2.92

Fixed remaining instances in GIT 075c3423 by adding chdir/getcwd wrappers to compat.h. This fix is labeled as "temporary" since the section these were added to is most likely due to be split off to a different file at some point (see: this issue), but future changes shouldn't break this fix.

Moving to: Archived MegaZeux Bugs