On 23/04/24 12:26, Jan Beulich wrote:
On 23.04.2024 12:02, Federico Serafini wrote:
--- a/docs/misra/deviations.rst
+++ b/docs/misra/deviations.rst
@@ -302,6 +302,19 @@ Deviations related to MISRA C:2012 Rules:
leave such files as is.
- Tagged as `deliberate` for ECLAIR.
+ * - R16.4
+ - Switch statements having a controlling expression of enum type
+ deliberately do not have a default case: gcc -Wall enables -Wswitch
+ which warns (and breaks the build as we use -Werror) if one of the enum
+ labels is missing from the switch.
+ - Tagged as `deliberate` for ECLAIR.
+
+ * - R16.4
+ - A switch statement with a single switch clause and no default label may
+ be used in place of an equivalent if statement if it is considered to
+ improve readability."
(I placed Rule 16.4 before Rule 16.3.
I will propose a new version with the correct ordering.)
First a terminology related comment here: I'm afraid "switch clause" can be
interpreted multiple ways, when I think we want to leave no room for
interpretation here. It's not even clear to me whether
switch ( x )
{
case 1: case 2: case 3: case 4:
...
break;
}
would be covered by the deviation, or whether the multiple case labels
wouldn't already be too much.
The MISRA C document, within Rule 16.1 ("A switch statement shall be
well-formed") defines the syntax rules that can be used to define a
"well formed" switch statement.
When I say "switch clause", I refer to the same entity the MISRA
document refers to in the definition of such syntax rules.
In the example above, we have a single switch clause with multiple
labels and no default label: this is a violation of Rule 16.4
("Every `switch' statement shall have a `default' label") which will
be covered by the deviation.
Do you think inserting the example in rules.rst or deviations.rst could
be useful?
And then it is not clear to me why
switch ( x )
{
case 1:
...
break;
default:
...
break;
}
shouldn't also be covered, as potentially a readability improvement /
future change simplification over
if ( x == 1 )
{
...
}
else
{
...
}
Here there are two switch clauses,
each of them terminated by a break statement,
and the default label is present:
the switch is well formed, no violations of series 16 will
be reported.
--
Federico Serafini, M.Sc.
Software Engineer, BUGSENG (http://bugseng.com)
