What about Macros for 14.3?

[Gavin McCall]

Code:

#define M1 ;

This macro breaks rule 19.4. Macro expanding to Null statement is not allowed.

Code:

#define M2
#define M3 /* comment */

This macro expands to no body, and is therefore not prohibited by 19.4.

A comment in a macro definition is removed by the pre-processor. Rule 14.3 applied before
Pre-processing. Treatment of M2 and M3 is identical.

Code:

M1

Since definition of M1 macro was invalid, its use is already a violation.

Code:

M2;
M3;

After pre-processing, these are both Null statements. Before pre-processing, there are characters before the Null statement. This is not allowed by 14.3.