[BUG|clang-tidy] false positive of misc-unconventional-assign-operator & cppcoreguidelines-c-copy-assignment-signature

[yaoxinliu]

struct A {
    explicit A(int) {
    }

    A& operator=(int n) {
        // ok, no clang-tidy warning as expected.
        return *this = A(n); 
    }
};

template<typename T>
struct B {
    explicit B(int) {
    }

    B& operator=(int n) {
        // clang-tidy warning: Operator=() should always return '*this'
        // clang-tidy rule: misc-unconventional-assign-operator
        // clang-tidy rule: cppcoreguidelines-c-copy-assignment-signature
        return *this = B(n); 
    }
};

clang-tidy version: 20.1.5.

This false positive will only be triggered for template classes; It doesn't occur for non-template classes.

[llvmbot]

@llvm/issue-subscribers-clang-tidy

Author: None (yaoxinliu)

``` struct A { explicit A(int) { }

A& operator=(int n) {
    // ok, no clang-tidy warning.
    return *this = A(n); 
}

};

template<typename T>
struct B {
explicit B(int) {
}

B& operator=(int n) {
    // clang-tidy warning: Operator=() should always return '*this'
    // clang-tidy    rule: misc-unconventional-assign-operator
    return *this = B(n); 
}

};

clang-tidy version: 20.1.5
</details>