warn_undefmacro

Controls the detection of undefined macros in #if and #elif directives.

Syntax

#pragma warn_undefmacro on | off | reset

Remarks

Example of Undefined Macro provides an example.

Listing 1. Example of Undefined Macro

#if BADMACRO == 4 /* WARNING: undefined macro. */

Use this pragma to detect the use of undefined macros (especially expressions) where the default value 0 is used. To suppress this warning message, check if defined first.

Note: A warning message is only issued when a macro is evaluated. A short-circuited " && " or " || " test or unevaluated " ?: " will not produce a warning message.

By default, this pragma is off .