If the --enable-release configure option is set then this warning appears when processing commandLine.cpp:
C++ base/commandLine.o
base/commandLine.cpp: In function ‘Common::String Base::parseCommandLine(Common::StringMap&, int, const char* const*)’:
base/commandLine.cpp:368:4: warning: ignoring return value of ‘long int strtol(const char*, char**, int)’, declared with attribute warn_unused_result
base/commandLine.cpp:380:4: warning: ignoring return value of ‘long int strtol(const char*, char**, int)’, declared with attribute warn_unused_result
base/commandLine.cpp:392:4: warning: ignoring return value of ‘long int strtol(const char*, char**, int)’, declared with attribute warn_unused_result
base/commandLine.cpp:412:4: warning: ignoring return value of ‘long int strtol(const char*, char**, int)’, declared with attribute warn_unused_result
base/commandLine.cpp:415:4: warning: ignoring return value of ‘long int strtol(const char*, char**, int)’, declared with attribute warn_unused_result
base/commandLine.cpp:418:4: warning: ignoring return value of ‘long int strtol(const char*, char**, int)’, declared with attribute warn_unused_result
base/commandLine.cpp:427:4: warning: ignoring return value of ‘long int strtol(const char*, char**, int)’, declared with attribute warn_unused_result
base/commandLine.cpp:489:4: warning: ignoring return value of ‘long int strtol(const char*, char**, int)’, declared with attribute warn_unused_result
base/commandLine.cpp:514:4: warning: ignoring return value of ‘long int strtol(const char*, char**, int)’, declared with attribute warn_unused_result
base/commandLine.cpp:517:4: warning: ignoring return value of ‘long int strtol(const char*, char**, int)’, declared with attribute warn_unused_result
Ticket imported from: #3304475. Ticket imported from: bugs/5706.
We intentionally ignore the return value of strtol in that place, so this compiler warning is misleading. You don't mention what compiler you are using, nor what operating system / SDK, so I have no idea how to even reproduce this; hence I can't even attempt to silence it.
But feel free to experiment with non-obtrusive ways to silence the warning (e.g. maybe replacing "strtol" by "(void)strtol" does it); if you find any, we will consider including it.
Closing.