如何关闭C源代码中的指定警告？

忽略某些警告的问题，也许GCC diagnostic pragmas可以提供帮助

GCC diagnostic pragmas：

6.57.10 Diagnostic Pragmas

GCC allows the user to selectively enable or disable certain types of diagnostics, and change the kind of the diagnostic. For example, a project's policy might require that all sources compile with -Werror but certain files might have exceptions allowing specific types of warnings. Or, a project might selectively enable diagnostics and treat them as errors depending on which preprocessor macros are defined.

#pragma GCC diagnostic kind option

Modifies the disposition of a diagnostic. Note that not all diagnostics are modifiable; at the moment only warnings (normally controlled by `-W...') can be controlled, and not all of them. Use -fdiagnostics-show-option to determine which diagnostics are controllable and which option controls them.

kind is `error' to treat this diagnostic as an error, `warning' to treat it like a warning (even if -Werror is in effect), or `ignored' if the diagnostic is to be ignored. option is a double quoted string which matches the command-line option.

          #pragma GCC diagnostic warning "-Wformat"
          #pragma GCC diagnostic error   "-Wformat"
          #pragma GCC diagnostic ignored "-Wformat"
     

Note that these pragmas override any command-line options. GCC keeps track of the location of each pragma, and issues diagnostics according to the state as of that point in the source file. Thus, pragmas occurring after a line do not affect diagnostics caused by that line.

#pragma GCC diagnostic push

#pragma GCC diagnostic pop

Causes GCC to remember the state of the diagnostics as of each push, and restore to that point at each pop. If a pop has no matching push, the command line options are restored.

          #pragma GCC diagnostic error "-Wuninitialized"
            foo(a);			/* error is given for this one */
          #pragma GCC diagnostic push
          #pragma GCC diagnostic ignored "-Wuninitialized"
            foo(b);			/* no diagnostic for this one */
          #pragma GCC diagnostic pop
            foo(c);			/* error is given for this one */
          #pragma GCC diagnostic pop
            foo(d);			/* depends on command line options */
     

GCC also offers a simple mechanism for printing messages during compilation.

#pragma message string

Prints string as a compiler message on compilation. The message is informational only, and is neither a compilation warning nor an error.

          #pragma message "Compiling " __FILE__ "..."
     

string may be parenthesized, and is printed with location information. For example,

          #define DO_PRAGMA(x) _Pragma (#x)
          #define TODO(x) DO_PRAGMA(message ("TODO - " #x))
          
          TODO(Remember to fix this)
     

prints `/tmp/file.c:4: note: #pragma message: TODO - Remember to fix this'.