rspec/rules/S3935/cfamily/rule.adoc

== Why is this an issue?

The GNU compiler gives the possibility to specify a range of consecutive values in a `case` label, for example: `+case: 1 ... 5+`.

However, if the values are written in decreasing order, i.e., from the larger value to the smaller one, the range will evaluate as empty. So the `case` body will never be executed.

== How to fix it

The rule raises an issue when a range specified in a `case` label is in decreasing order. Swap the values to define a valid range.

=== Code examples

==== Noncompliant code example

[source,cpp,diff-id=1,diff-type=noncompliant]
----
switch (i) {
  case 0: 
    //...
    break;
  case 1 ... 2:
    //...
    break;
  case 5 ... 3: // Noncompliant: it evaluates as empty, so the code will never be executed
    //...
    break;
----

==== Compliant solution

[source,cpp,diff-id=1,diff-type=compliant]
----
switch (i) {
  case 0: 
    //...
    break;
  case 1 ... 2:
    //...
    break;
  case 3 ... 5
    //...
    break;
----

== Resources

=== Documentation

* GCC - https://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html[Case Ranges]


ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Reverse or otherwise refactor this range; it doesn't match any value.


=== Highlighting

``++x...y++``


endif::env-github,rspecator-view[]