MISRA.UNDEF.NOTGLOBAL

Undef not at the global level.

MISRA-C Rule 19.5 (required): Macros shall not be #define"™d or #undef"™d within a block.

This rule is also covered by MISRA.DEFINE.NOTGLOBAL.

While it is legal C to place #define or #undef directives anywhere in a code file, placing them inside blocks is misleading as it implies a scope restricted to that block, which is not the case.

Normally, #define directives will be placed near the start of a file, before the first function definition. Normally, #undef directives will not be needed (see Rule 19.6).

MISRA-C++ Rule 16-0-2 (required): Macros shall only be #define"™d or #undef"™d in the global namespace.

This rule is also covered by MISRA.DEFINE.NOTGLOBAL.

Rationale

While it is legal to place #define or #undef directives anywhere in a source file, placing them outside of the global namespace is misleading as their scope is not restricted. This may be inconsistent with developer expectations.

Example

#ifndef MY_HDR
#define MY_HDR     // Compliant

namespace NS
{
   #define FOO     // Non-compliant
   #undef FOO      // Non-compliant
}
#endif