Failure to compile with -fno-common

[insanitywholesale]

Expected Behavior

Successful compilation with -fno-common

Current Behavior

Compilation failure when using -fno-common

Failure Information (for bugs)

Context

Adding -fno-common to CFLAGS is all I needed to produce this issue

• DF-SHOW Version: v0.8.2-beta
• Operating System: Gentoo
• System Architecture: amd64
• Output of uname -a: Linux puddle 4.19.97-gentoo Develop to Master #1 SMP Sun Jan 19 23:53:56 EET 2020 x86_64 Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz GenuineIntel GNU/Linux

Failure Logs

make -j9
make  all-am
make[1]: Entering directory '/var/tmp/portage/app-misc/dfshow-0.8.2_beta/work/dfshow-0.8.2-beta'
x86_64-pc-linux-gnu-gcc -DHAVE_CONFIG_H -I.    -DSYSCONFIG=\"/etc\" -DDATADIR=\"/usr/share/dfshow\" -D_XOPEN_SOURCE_EXTENDED -march=native -mtune=native -O2 -pipe -fno-common -c -o src/show.o src/show.c
x86_64-pc-linux-gnu-gcc -DHAVE_CONFIG_H -I.    -DSYSCONFIG=\"/etc\" -DDATADIR=\"/usr/share/dfshow\" -D_XOPEN_SOURCE_EXTENDED -march=native -mtune=native -O2 -pipe -fno-common -c -o src/showfunctions.o src/showfunctions.c
x86_64-pc-linux-gnu-gcc -DHAVE_CONFIG_H -I.    -DSYSCONFIG=\"/etc\" -DDATADIR=\"/usr/share/dfshow\" -D_XOPEN_SOURCE_EXTENDED -march=native -mtune=native -O2 -pipe -fno-common -c -o src/showmenus.o src/showmenus.c
x86_64-pc-linux-gnu-gcc -DHAVE_CONFIG_H -I.    -DSYSCONFIG=\"/etc\" -DDATADIR=\"/usr/share/dfshow\" -D_XOPEN_SOURCE_EXTENDED -march=native -mtune=native -O2 -pipe -fno-common -c -o src/colors.o src/colors.c
x86_64-pc-linux-gnu-gcc -DHAVE_CONFIG_H -I.    -DSYSCONFIG=\"/etc\" -DDATADIR=\"/usr/share/dfshow\" -D_XOPEN_SOURCE_EXTENDED -march=native -mtune=native -O2 -pipe -fno-common -c -o src/common.o src/common.c
x86_64-pc-linux-gnu-gcc -DHAVE_CONFIG_H -I.    -DSYSCONFIG=\"/etc\" -DDATADIR=\"/usr/share/dfshow\" -D_XOPEN_SOURCE_EXTENDED -march=native -mtune=native -O2 -pipe -fno-common -c -o src/sf.o src/sf.c
x86_64-pc-linux-gnu-gcc -DHAVE_CONFIG_H -I.    -DSYSCONFIG=\"/etc\" -DDATADIR=\"/usr/share/dfshow\" -D_XOPEN_SOURCE_EXTENDED -march=native -mtune=native -O2 -pipe -fno-common -c -o src/sfmenus.o src/sfmenus.c
src/show.c: In function 'main':
src/show.c:936:9: warning: ignoring return value of 'getcwd', declared with attribute warn_unused_result [-Wunused-result]
  936 |         getcwd(tmpPwd, sizeof(currentpwd));
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/show.c:942:7: warning: ignoring return value of 'chdir', declared with attribute warn_unused_result [-Wunused-result]
  942 |       chdir(currentpwd);
      |       ^~~~~~~~~~~~~~~~~
src/show.c:944:7: warning: ignoring return value of 'getcwd', declared with attribute warn_unused_result [-Wunused-result]
  944 |       getcwd(currentpwd, sizeof(currentpwd));
      |       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/common.c: In function 'wReadLine':
src/common.c:532:5: warning: implicit declaration of function 'get_wch'; did you mean 'getwc'? [-Wimplicit-function-declaration]
  532 |     get_wch(&c);
      |     ^~~~~~~
      |     getwc
src/common.c: In function 'showManPage':
src/common.c:780:3: warning: ignoring return value of 'system', declared with attribute warn_unused_result [-Wunused-result]
  780 |   system("clear"); // Needed to ensure man pages display correctly
      |   ^~~~~~~~~~~~~~~
src/common.c:781:3: warning: ignoring return value of 'system', declared with attribute warn_unused_result [-Wunused-result]
  781 |   system(mancmd);
      |   ^~~~~~~~~~~~~~
x86_64-pc-linux-gnu-gcc -DSYSCONFIG=\"/etc\" -DDATADIR=\"/usr/share/dfshow\" -D_XOPEN_SOURCE_EXTENDED -march=native -mtune=native -O2 -pipe -fno-common  -Wl,-O1 -Wl,--as-needed -o bin/sf src/sf.o src/sfmenus.o src/colors.o src/common.o -lncursesw -lm -lconfig -ltinfow
src/showmenus.c: In function 'refreshDirectory':
src/showmenus.c:334:5: warning: ignoring return value of 'chdir', declared with attribute warn_unused_result [-Wunused-result]
  334 |     chdir(currentpwd);
      |     ^~~~~~~~~~~~~~~~~
src/showmenus.c: In function 'show_directory_input':
src/showmenus.c:393:7: warning: ignoring return value of 'chdir', declared with attribute warn_unused_result [-Wunused-result]
  393 |       chdir(currentpwd);
      |       ^~~~~~~~~~~~~~~~~
src/showmenus.c: In function 'linktext_input':
src/showmenus.c:1357:13: warning: ignoring return value of 'symlink', declared with attribute warn_unused_result [-Wunused-result]
 1357 |             symlink(relativeFile, target);
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/showmenus.c:1360:13: warning: ignoring return value of 'symlink', declared with attribute warn_unused_result [-Wunused-result]
 1360 |             symlink(file, target);
      |             ^~~~~~~~~~~~~~~~~~~~~
src/showmenus.c:1363:11: warning: ignoring return value of 'link', declared with attribute warn_unused_result [-Wunused-result]
 1363 |           link(file, target);
      |           ^~~~~~~~~~~~~~~~~~
src/showmenus.c: In function 'directory_view_menu_inputs':
src/showmenus.c:1519:15: warning: ignoring return value of 'chdir', declared with attribute warn_unused_result [-Wunused-result]
 1519 |               chdir(currentpwd);
      |               ^~~~~~~~~~~~~~~~~
src/showmenus.c:1569:15: warning: ignoring return value of 'chdir', declared with attribute warn_unused_result [-Wunused-result]
 1569 |               chdir(currentpwd);
      |               ^~~~~~~~~~~~~~~~~
src/showmenus.c:1581:15: warning: ignoring return value of 'chdir', declared with attribute warn_unused_result [-Wunused-result]
 1581 |               chdir(currentpwd);
      |               ^~~~~~~~~~~~~~~~~
src/showfunctions.c: In function 'get_dir':
src/showfunctions.c:1607:33: warning: format '%d' expects argument of type 'int', but argument 3 has type '__nlink_t' {aka 'long unsigned int'} [-Wformat=]
 1607 |             sprintf(hlinkstr, "%d", buffer.st_nlink);
      |                                ~^   ~~~~~~~~~~~~~~~
      |                                 |         |
      |                                 int       __nlink_t {aka long unsigned int}
      |                                %ld
src/showfunctions.c: In function 'writeResultStruct':
src/showfunctions.c:547:5: warning: ignoring return value of 'readlink', declared with attribute warn_unused_result [-Wunused-result]
  547 |     readlink(filename, ob[count].slink, cslinklen);
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/showfunctions.c: In function 'LaunchShell':
src/showfunctions.c:961:3: warning: ignoring return value of 'write', declared with attribute warn_unused_result [-Wunused-result]
  961 |   write(STDOUT_FILENO, "\nUse 'exit' to return to Show.\n\n", 32);
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/showfunctions.c:962:3: warning: ignoring return value of 'system', declared with attribute warn_unused_result [-Wunused-result]
  962 |   system(getenv("SHELL"));
      |   ^~~~~~~~~~~~~~~~~~~~~~~
src/showfunctions.c: In function 'LaunchExecutable':
src/showfunctions.c:971:3: warning: ignoring return value of 'system', declared with attribute warn_unused_result [-Wunused-result]
  971 |   system("clear"); // Just to be sure
      |   ^~~~~~~~~~~~~~~
src/showfunctions.c:972:3: warning: ignoring return value of 'system', declared with attribute warn_unused_result [-Wunused-result]
  972 |   system(command);
      |   ^~~~~~~~~~~~~~~
src/showfunctions.c: In function 'get_dir':
src/showfunctions.c:1636:13: warning: ignoring return value of 'chdir', declared with attribute warn_unused_result [-Wunused-result]
 1636 |             chdir(path);
      |             ^~~~~~~~~~~
src/showfunctions.c:1681:7: warning: ignoring return value of 'chdir', declared with attribute warn_unused_result [-Wunused-result]
 1681 |       chdir(path);
      |       ^~~~~~~~~~~
x86_64-pc-linux-gnu-gcc -DSYSCONFIG=\"/etc\" -DDATADIR=\"/usr/share/dfshow\" -D_XOPEN_SOURCE_EXTENDED -march=native -mtune=native -O2 -pipe -fno-common  -Wl,-O1 -Wl,--as-needed -o bin/show src/show.o src/showfunctions.o src/showmenus.o src/colors.o src/common.o -lncursesw -lm -lconfig -ltinfow
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: src/colors.o:(.bss+0x20): multiple definition of `errmessage'; src/showmenus.o:(.bss+0x320): first defined here
collect2: error: ld returned 1 exit status
make[1]: *** [Makefile:462: bin/show] Error 1
make[1]: Leaving directory '/var/tmp/portage/app-misc/dfshow-0.8.2_beta/work/dfshow-0.8.2-beta'
make: *** [Makefile:340: all] Error 2

[insanitywholesale]

for some context as to why -fno-common was used, it will be enabled by default with gcc10 so this is just planning ahead and testing a bit. I managed to fix the issue locally by changing char errmessage[256]; to extern char errmessage[256]; in src/showmenus.c but since I'm not a good programmer, let alone in C, I thought I should mention it and leave the final decision for how to fix this up to you.

[roberthawdon]

Thanks for the submission, the fix has been pushed into the master branch. Cheers.