How do you disable the unused variable warnings coming out of gcc in 3rd party code I do not wish to edit

Question

I d like to know what switch you pass to the gcc compiler to turn off unused variable warnings   I m getting errors out of boost on windows and I do not want to touch the boost code   C  boost 1 52 0 boost system error code hpp  At global scope  C  boost 1 52 0 boost system error code hpp 214 36  error   boost  system  posix category  defined but not used  -Werror unused-variable  C  boost 1 52 0 boost system error code hpp 215 36  error   boost  system  errno ecat  defined but not used  -Werror unused-variable  C  boost 1 52 0 boost system error code hpp 216 36  error   boost  system  native ecat  defined but not used  -Werror unused-variable    I tried using both -Wunused-value and -Wno-unused-value but neither suppressed the messages above   What is the right command  here is my compile line   g    -g -fno-inline -Wall -Werror -Wextra -Wfloat-equal -Wshadow -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wno-conversion  -Wdisabled-optimization -Wredundant-decls -Wunused-value -Wno-deprecated  -IC   boost 1 52 0 -D LARGEFILE SOURCE -D LARGEFILE64 SOURCE -D FILE OFFSET BITS 64  -c -o op o op cpp   Perhaps the -Wall overrides my goal

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export IGNORE WARNINGS 1   It does display warnings  but continues with the build

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How do you disable the unused variable warnings coming out of gcc    I m getting errors out of boost on windows and I do not want to touch the boost code      You visit Boost s Trac and file a bug report against Boost   Your application is not responsible for clearing library warnings and errors  The library is responsible for clearing its own warnings and errors

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-Wall and -Wextra sets the stage in GCC and the subsequent -Wno-unused-variable may not take effect   For example  if you have   CFLAGS    -std c99 -pedantic -pedantic-errors -Werror -g0 -Os       -fno-strict-overflow -fno-strict-aliasing       -Wall -Wextra       -pthread       -Wno-unused-label       -Wno-unused-function       -Wno-unused-parameter       -Wno-unused-variable         INC   then GCC sees the instruction -Wall -Wextra and seems to ignore -Wno-unused-variable  This can instead look like this below and you get the desired effect of not being stopped in your compile on the unused variable   CFLAGS    -std c99 -pedantic -pedantic-errors -Werror -g0 -Os       -fno-strict-overflow -fno-strict-aliasing       -pthread       -Wno-unused-label       -Wno-unused-function         INC   There is a good reason it is called a  warning  vs an  error   Failing the compile just because you code is not complete  say you are stubbing the algorithm out  can be defeating

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Use -Wno-unused-variable should work

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See man gcc under Warning Options  There you have a whole bunch of unused      Warning Options       -Wunused -Wunused-function -Wunused-label -Wunused-parameter -Wunused-value -Wunused-variable -Wunused-but-set-parameter -Wunused-but-set-variable   If you prefix any of them with no-  it will disable this warning      Many options have long names starting with -f or with -W---for example  -fmove-loop-invariants  -Wformat and so on  Most of these have both positive and negative forms  the negative form of -ffoo would be -fno-foo  This manual documents only one of these two forms  whichever one is not the default    More detailed explanation can be found at Options to Request or Suppress Warnings

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Sometimes you just need to suppress only some warnings and you want to keep other warnings  just to be safe  In your code  you can suppress the warnings for variables and even formal parameters by using GCC s unused attribute  Lets say you have this code snippet   void func unsigned number  const int version      unsigned tmp    std  cout  lt  lt  number  lt  lt  std  endl      There might be a situation  when you need to use this function as a handler - which  imho  is quite common in C   Boost library  Then you need the second formal parameter version  so the function s signature is the same as the template the handler requires  otherwise the compilation would fail  But you don t really need it in the function itself either     The solution how to mark variable or the formal parameter to be excluded from warnings is this    void func unsigned number  const int version   attribute    unused        unsigned tmp   attribute    unused      std  cout  lt  lt  number  lt  lt  std  endl      GCC has many other parameters  you can check them in the man pages  This also works for the C programs  not only C    and I think it can be used in almost every function  not just handlers  Go ahead and try it      P S   Lately I used this to suppress warnings of Boosts  serialization in template like this   template  lt typename Archive gt  void serialize Archive  amp ar  const unsigned int version   attribute    unused      EDIT  Apparently  I didn t answer your question as you needed  drak0sha done it better  It s because I mainly followed the title of the question  my bad  Hopefully  this might help other people  who get here because of that title

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The compiler is already telling you  it s not value but variable  You are looking for -Wno-unused-variable  Also  try g   --help warnings to see a list of available options

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If you re using gcc and want to disable the warning for selected code  you can use the  pragma compiler directive    pragma GCC diagnostic push  pragma GCC diagnostic ignored  -Wunused-variable    your problematic library includes    pragma GCC diagnostic pop   For code you control  you may also use   attribute    unused   to instruct the compiler that specific variables are not used

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The -Wno-unused-variable switch usually does the trick  However  that is a very useful warning indeed if you care about these things in your project  It becomes annoying when GCC starts to warn you about things not in your code though   I would recommend you keeping the warning on  but use -isystem instead of -I for include directories of third-party projects  That flag tells GCC not to warn you about the stuff you have no control over   For example  instead of -IC   boost 1 52 0  say -isystem C   boost 1 52 0   Hope it helps  Good Luck

[c++] How do you disable the unused variable warnings coming out of gcc in 3rd party code I do not wish to edit?

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