MISRA C:2012 Rule 16.1

R2026b

All switch statements shall be well-formed

Description

All switch statements shall be well-formed¹

Rationale

The syntax for switch statements in C is not particularly rigorous and can allow complex, unstructured behavior. This rule and other rules impose a simple consistent structure on the switch statement.

Polyspace Implementation

The rule checker shows a violation if a switch statement violates one of the following:

• The switch statement has a default label.

• Every switch clause ends with an unconditional break statement.

• The switch statement has at least two switch clauses.

• The default label is either the first or the last switch label of the switch statement.

• Switch labels appear at the outermost level of the switch body.

• A break statement in a switch clause is the last statement of the clause.

• No statement appears before the first switch label.

• The child statement of the switch statement is a compound statement.

• All switch clauses appear at the same level.

• Switch clauses contain only switch labels and switch clauses, and no other code.

• The switch statement contains only switch labels and switch clauses, and no other code.

Troubleshooting

If you expect a rule violation but do not see it, refer to Diagnose Why Coding Standard Violations Do Not Appear as Expected.

Check Information

Group: Switch Statements

Category: Required

AGC Category: Advisory

PQL Name: std.misra_c_2012.R16_1

Version History

R2024a: Default case containing no statement or comment other than break;

The rule checker does not report a violation when a switch statement contains a default case with no statements or comments other than break;. The default case must contain a break statement, but a statement list or comments are optional.

void example (int i) {
    switch(i) {
        case 0:
        case 1:
            i++;
            break;
        case 2:
        default:               // Compliant
            break;
    }
}