Rationale (February, 2012):

The resolution of issue 903 makes it clear that false is not a null pointer constant.

Although 6.8.2 [basic.fundamental] paragraph 7 classifies bool as an integral type, the values of true and false are not specified — only that the results of converting them to another integral type are 1 and 0, respectively. This omission leaves unspecified whether false is an integral null pointer constant or not.