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.. title:: clang-tidy - hicpp-multiway-paths-covered
hicpp-multiway-paths-covered
============================
This check discovers situations where code paths are not fully-covered.
It furthermore suggests using ``if`` instead of ``switch`` if the code will be more clear.
The `rule 6.1.2 <http://www.codingstandard.com/rule/6-1-2-explicitly-cover-all-paths-through-multi-way-selection-statements/>`_
and `rule 6.1.4 <http://www.codingstandard.com/rule/6-1-4-ensure-that-a-switch-statement-has-at-least-two-case-labels-distinct-from-the-default-label/>`_
of the High Integrity C++ Coding Standard are enforced.
``if-else if`` chains that miss a final ``else`` branch might lead to unexpected
program execution and be the result of a logical error.
If the missing ``else`` branch is intended you can leave it empty with a clarifying
comment.
This warning can be noisy on some code bases, so it is disabled by default.
.. code-block:: c++
void f1() {
int i = determineTheNumber();
if(i > 0) {
// Some Calculation
} else if (i < 0) {
// Precondition violated or something else.
}
// ...
}
Similar arguments hold for ``switch`` statements which do not cover all possible code paths.
.. code-block:: c++
// The missing default branch might be a logical error. It can be kept empty
// if there is nothing to do, making it explicit.
void f2(int i) {
switch (i) {
case 0: // something
break;
case 1: // something else
break;
}
// All other numbers?
}
// Violates this rule as well, but already emits a compiler warning (-Wswitch).
enum Color { Red, Green, Blue, Yellow };
void f3(enum Color c) {
switch (c) {
case Red: // We can't drive for now.
break;
case Green: // We are allowed to drive.
break;
}
// Other cases missing
}
The `rule 6.1.4 <http://www.codingstandard.com/rule/6-1-4-ensure-that-a-switch-statement-has-at-least-two-case-labels-distinct-from-the-default-label/>`_
requires every ``switch`` statement to have at least two ``case`` labels other than a `default` label.
Otherwise, the ``switch`` could be better expressed with an ``if`` statement.
Degenerated ``switch`` statements without any labels are caught as well.
.. code-block:: c++
// Degenerated switch that could be better written as `if`
int i = 42;
switch(i) {
case 1: // do something here
default: // do somethe else here
}
// Should rather be the following:
if (i == 1) {
// do something here
}
else {
// do something here
}
.. code-block:: c++
// A completely degenerated switch will be diagnosed.
int i = 42;
switch(i) {}
Options
-------
.. option:: WarnOnMissingElse
Boolean flag that activates a warning for missing ``else`` branches.
Default is `0`.
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