Why is this an issue?
Proprietary compiler extensions can be handy, but they commit you to always using that compiler. This rule raises an issue when GNU extensions are
used, such as:
- Ternary operator with omitted second operand
- Case ranges in switch statements
- Expression statements, i.e. code blocks producing value
- Index range in array initializers
- A array initializer without
=
- A structure member initializer with a colon
- Decimal floating points numbers
_Decimal32, _Decimal64, and _Decimal128
- Structures and union without named data members
Noncompliant code example
struct S {
int f;
};
struct S s[] = {
[0] { // Noncompliant
f : 0 // Noncompliant
}
[1 ... 3] = { // CHECK :8 :11 S3715:use of GNU array range extension
.f = 2
}
};
int fun(int p) {
switch (p) {
case 0 ... 1: // Noncompliant
do_the_thing();
break;
case 2:
//...
}
p = ({ // Noncompliant
int a = 10, b = 20;
(a * b) + 10;
});
return p ?: 0; // Noncompliant
}
_Decimal32 d32; // Noncompliant
struct Empty {}; // Noncompliant in C
Compliant solution
struct S {
int f;
};
struct S s[] = {
[0] = {
.f = 0
},
[1] = {
.f = 2
}
[2] = {
.f = 2
},
[3] = {
.f = 2
}
};
int fun(int p) {
switch (p) {
case 0:
case 1:
do_the_thing();
break;
case 2:
//...
}
int a = 10, b = 20;
p = (a * b) + 10;
return p ? p: 0;
}
