MISRA.GOTO.NESTED.2012

MISRA C 2012 Rule 15.3: Any label referenced by a goto statement shall be declared in the same block, or in any block enclosing the goto statement

Category: Required

Analysis: Decidable, Single Translation Unit

Applies to: C90, C99

Amplification

For the purposes of this rule, a switch-clause that does not consist of a compound statement is treated as if it were a block.

Rationale

Unconstrained use of goto can lead to programs that are unstructured and extremely difficult to understand.

Preventing jumps between blocks, or into nested blocks, helps to minimize visual code complexity.

Example

void f1 ( int32_t a )
{
    if ( a <= 0 )
    {
        goto L2;   /* Non-compliant */
    }

    goto L1;       /* Compliant     */

    if ( a == 0 )
    {
        goto L1;   /* Compliant     */
    }
    goto L2;       /* Non-compliant */

L1:
    if ( a > 0 )
    {
    L2:
      ;
    }
}

In the following example, the label L1 is defined in a block which encloses the block containing the goto statement. However, the jump crosses from one switch-clause to another and, since switch-clauses are treated like blocks for the purposes of this rule, the goto statement is non-compliant.

switch ( x )
{
    case 0:
       if ( x == y )
       {
           goto L1;
       }
       break;
    case 1:
        y = x;
L1:
    ++x;
    break;
  default:
    break;
}