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
and rule 6.1.4
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.
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.
// 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
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.
// 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
}
// A completely degenerated switch will be diagnosed.
int i = 42;
switch(i) {}