Null statements should not normally be deliberately included, but where they are used they shall appear on a line by themselves. White-space characters may precede the null statement to preserve indentation. If a comment follows the null statement then at least one white-space character shall separate the null statement from the comment. The use of a white-space character to separate the null statement from any following comment is required because it provides an important visual cue to reviewers. Following this rule enables a static checking tool to warn of null statements appearing on a line with other text, which would normally indicate a programming error.

Example

while ( ( port & 0x80 ) == 0 )
{
   ; /* wait for pin - Compliant */
   /* wait for pin */ ; /* Not compliant, comment before ; */
   ;/* wait for pin - Not compliant, no white-space char after ; */
}

MISRA-C++ Rule 6-2-3 (required): Before preprocessing, a null statement shall only occur on a line by itself; it may be followed by a comment, provided that the first character following the null statement is a white-space character.

Rationale

Null statements should not normally be included deliberately, but where they are used, they shall appear on a line by themselves. White-space characters may precede the null statement to preserve indentation. If a comment follows the null statement, then at least one white-space character shall separate the null statement from the comment. The use of a white-space character to separate the null statement from any following comment is required on the grounds that it provides an important visual cue to reviewers. Following this rule enables a static checking tool to warn of null statements appearing on a line with other text, which would normally indicate a programming error.

Example

while ( ( port & 0x80 ) == 0 )
{
   ; // wait for pin - Compliant
   /* wait for pin */ ; // Non-compliant, comment before ;
   ;// wait for pin — Non-compliant, no white-space char after ;
}