Proverbially Playing the `Devil's Advocate' for Rule 15-1-2

Proverbially Playing the `Devil's Advocate' for Rule 15-1-2 - Printable Version

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Proverbially Playing the `Devil's Advocate' for Rule 15-1-2 - gs - 11-09-2008

The text and rationale of rule 15-1-2 make no mention of the word `macro'. Let us suppose an application made no reference to the Standard Library within it's source code. Consequently, the `NULL' macro has not been defined. Would the following code violate rule 15-1-2?

Code:
class A {};

A NULL;

void f()

    {

    throw NULL;

    }

The very premise of the rationale for the rule is invalid. In this case a `throw NULL;' is not equivalent to `throw (0);' and is not a throwing of an integer expression.

Furthermore, the wording of the rationale is slightly incorrect:

Quote:throw(NULL) (equivalent to throw(0)) is never a throw of the null-pointer-constant ...

To quote ISO C++, 18.1, para. 4, (lib.support.types):

Quote:The macro NULL is an implementation-defined C++ null pointer constant in this International Standard
(4.10).

Granted, the referenced `4.10' states a null pointer constant has integer (not pointer) type. However, the macro is a null pointer constant.

Re: Proverbially Playing the `Devil's Advocate' for Rule 15-1-2 - misra cpp - 07-10-2015

Rule 17-0-2 disallows the reuse of names of standard library MACROs. Reusing NULL is therefore a violation of this rule.