[clang-tidy] More fine-grained options for readability-implicit-bool-conversion

[chrchr-github]

enum E : long { E0, E1 };
E f();
bool g(int i, double d) {
    if (i) {}
    if (d) {}
    return f();
}

In the code above, three instances of readability-implicit-bool-conversion are detected. However, in some code bases, similar if conditions are very common and do not cause issues, whereas conversion from an enum might be a serious bug.
It would be nice to have more control over readability-implicit-bool-conversion warnings by either type involved (enum vs numerical) or usage (if vs return).

[llvmbot]

@llvm/issue-subscribers-clang-tidy

[PiotrZSL]

Clang-tidy 17 got bugprone-non-zero-enum-to-bool-conversion, but still I agree that conversions like int -> bool are very common, and usually not an issue.

[PiotrZSL]

Check already got options AllowIntegerConditions and AllowPointerConditions, it should do a trick.

[chrchr-github]

Check already got options AllowIntegerConditions and AllowPointerConditions, it should do a trick.

I must have missed those options, thanks. It might still be worth adding AllowFloatConditions as well.

[chrchr-github]

An option to allow conversions from binary & would also be useful:

bool f(int i) {
    const int flag = 16;
    return i & flag;
}

[chrchr-github]

It seems that this still gets flagged even with AllowPointerConditions:

void f(bool b, int* p) {
    if (b && !p) {}
}

Edit: apparently that was a bad reduction, and AllowPointerConditions is to be taken literally. Here's an example that still gets flagged with AllowPointerConditions :

bool f(bool b, int* p, int* q) {
    b = b && p;
    return b && q;
}

https://godbolt.org/z/r9734cn3f

[aeubanks]

It would be nice to have an option to only check for bool->int conversions and not the other way around. As mentioned previously here, int to bool is usually fine and occurs a lot in codebases, but we have seen cases where a bool->int conversion caused a bug and would just like to check for that.

[chrchr-github]

Related: #36323