`RULE-0-1-1`: Findings should be suppressed for [[maybe_unused]] initialization

[MichaelRFairhurst]

Affected rules

• RULE-0-1-1

Description

If the assignment is initializing a variable with the [[maybe_unused]] attribute, we should not report this.

The presence of [[maybe_unused]] disables other rules according to the MISRA spec, and we should follow that principle here as well. If a variable is [[maybe_unused]], that strongly indicates that there's some kind of conditional compilation that uses the variable value, and that the write is ok.

Note that [[maybe_unused]] should not disable all violations of the rule, only ones that would be fixed by adding any read to the variable.

Example

void example_function() {
  [[maybe_unused]] int x = 0; // reported, but should not be.
  
  [[maybe_unused]] int y = 1; // should still be reported
  y = 2;

  [[maybe_unused]] int z = 3;
  f(z);
  z = 4; // should still be reported.
}