MISRA C++:2008 Rule 6-2-3

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

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Description

Rule Definition

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

A null statement:

used on a line with other code can indicate a programming error. If you want to enter a null statement, place the statement on a line by itself.

A comment can follow a null statement, but use a white space character between the null statement and the comment to provide a visual cue for reviewers.

Polyspace Implementation

The rule checker considers a null statement as a line where the first character excluding comments is a semicolon. The rule checker reports violations for situations where:

Comments appear before the null statement.
For instance:
```
/* wait for pin */ ; 
```
Comments appear immediately after the semicolon without a white space in between.
For instance:
```
;// wait for pin
```

The rule checker also reports a violation when a second statement appears on the same line following the null statement.

For instance:

; count++;

Troubleshooting

If you expect a rule violation but Polyspace^® does not report it, see Diagnose Why Coding Standard Violations Do Not Appear as Expected.

Examples

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Proper Formatting for Null Statement

In this example, there are three different versions of comments after a null statement.

The first option is compliant. The comment comes after the null statement, the null statement is the only statement on the line, and there is a white space separating the semicolon and the comment.
The second option is noncompliant. The comment comes before the null statement.
The third option is noncompliant. A white space does not separate the semicolon and comment.

#include <iostream>

void main()
{
	std::cout << "Hello World" << std::endl;
	 ; // comment here - Compliant     
	 /* comment here */ ; // Noncompliant
	 ;//comment here - Noncompliant
	
}

Check Information

Group: Statements

Category: Required

Version History

Introduced in R2013b