| Issue |
63464
|
| Summary |
[clang-tidy] readability-const-return-type conflicts with cert-dcl21-cpp for postfix operators
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
ecorm
|
[`cert-dcl21-cpp`](https://clang.llvm.org/extra/clang-tidy/checks/cert/dcl21-cpp.html) wants postfix increment/decrement operators to return a `const` value, because otherwise:
> any modifications made to the resulting object from calling operator++(int) would be modifying a temporary object
But [`readability-const-return-type`](https://clang.llvm.org/extra/clang-tidy/checks/readability/const-return-type.html) prohibits returning `const`value types, because
> Such use of _const_ is usually superfluous, and can prevent valuable compiler optimizations.
The `readability-const-return-type` check should be relaxed for postfix increment/decrement operators, because avoiding bugs should take precedence over a minor readability warning.
Example program:
```c++
struct Foo
{
int value = 0;
};
struct Bar
{
// warning: overloaded 'operator++' returns a non-constant object
// instead of a constant object type [cert-dcl21-cpp]
Bar operator++(int)
{
auto temp = *this;
++foo.value;
return temp;
}
Foo foo;
};
struct Baz
{
// warning: return type 'const Baz' is 'const'-qualified at the top
// level, which may reduce code readability without improving const
// correctness [readability-const-return-type]
const Baz operator++(int)
{
auto temp = *this;
++foo.value;
return temp;
}
Foo foo;
};
int main()
{
Bar bar;
bar++;
Baz baz;
baz++;
return 0;
}
```
Godbolt demo: https://godbolt.org/z/E64zeKvzr
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