30.1.2 Severity Pragmas

These pragmas control the severity of classes of diagnostics. You can specify the class of diagnostic with the GCC option that causes those diagnostics to be generated.

#pragma GCC diagnostic error option

_Pragma ("GCC diagnostic error option")

For code following this pragma, treat diagnostics of the variety specified by option as errors. For example:

_Pragma ("GCC diagnostic error -Wformat")

specifies to treat diagnostics enabled by the -Wformat option as errors rather than warnings.

#pragma GCC diagnostic warning option

_Pragma ("GCC diagnostic warning option")

For code following this pragma, treat diagnostics of the variety specified by option as warnings. This overrides the -Werror option which says to treat warnings as errors.

#pragma GCC diagnostic ignore option

_Pragma ("GCC diagnostic ignore option")

For code following this pragma, refrain from reporting any diagnostics of the variety specified by option.

#pragma GCC diagnostic push

_Pragma ("GCC diagnostic push")

#pragma GCC diagnostic pop

_Pragma ("GCC diagnostic pop")

These pragmas maintain a stack of states for severity settings. ‘GCC diagnostic push’ saves the current settings on the stack, and ‘GCC diagnostic pop’ pops the last stack item and restores the current settings from that.

‘GCC diagnostic pop’ when the severity setting stack is empty restores the settings to what they were at the start of compilation.

Here is an example:

_Pragma ("GCC diagnostic error -Wformat")

/* -Wformat messages treated as errors.  */

_Pragma ("GCC diagnostic push")
_Pragma ("GCC diagnostic warning -Wformat")

/* -Wformat messages treated as warnings.  */

_Pragma ("GCC diagnostic push")
_Pragma ("GCC diagnostic ignored -Wformat")

/* -Wformat messages suppressed.  */

_Pragma ("GCC diagnostic pop")

/* -Wformat messages treated as warnings again.  */

_Pragma ("GCC diagnostic pop")

/* -Wformat messages treated as errors again.  */

/* This is an excess ‘pop’ that matches no ‘push’.  */
_Pragma ("GCC diagnostic pop")

/* -Wformat messages treated once again
   as specified by the GCC command-line options.  */