[cfe-dev] Clang not generating the destructor

[Nathan Sidwell via cfe-dev]

On 4/28/21 9:55 PM, Riyaz Puthiyapurayil via cfe-dev wrote:
> The following test case fails to compile with clang++ because it does 
> not generate code for a destructor (as indicated below). Is this a bug 
> or am I missing something? Gcc works fine.

smells like a bug.

> 
> Wandbox permlink: https://wandbox.org/permlink/H7BcjQzXwoqZclj3 
> <https://wandbox.org/permlink/H7BcjQzXwoqZclj3>
> 
> // prog.cpp
> 
> #include "D.h"
> 
> D *f(char c) {
> 
>    return c ? new D(c) : new D(-1);
> 
> }
> 
> D *x;
> 
> int main() {
> 
>    x = f('a');
> 
>    return 0;
> 
> }
> 
> // D.h
> 
> #ifndef D_H
> 
> #define D_H
> 
> extern void unknown();
> 
> template<typename T>
> 
> class C {
> 
>    T t;
> 
> public:
> 
>    explicit C(T t_) : t(t_) {}
> 
>    ~C() {}
> 
> };
> 
> class D {
> 
>    union U
> 
>    {
> 
>      explicit U(int i)  : ci(i) { unknown(); }
> 
>      explicit U(char c) : cc(c) {}
> 
>      ~U() {}
> 
>      C<int>  ci;    // destructor C<int>::~C() not generated
> 
>      C<char> cc;
> 
>    };
> 
>    U u;
> 
>    bool uIsInt;
> 
> public:
> 
>    explicit D(int i)  : u(i), uIsInt(true)  {}
> 
>    explicit D(char c) : u(c), uIsInt(false) {}
> 
>    ~D(); // explicit destruction of u
> 
> };
> 
> D* f(char c);
> 
> #endif // D_H
> 
> // unk.cpp
> 
> #include "D.h"
> 
> void unknown() {}
> 
> D::~D() {
> 
>    if (uIsInt)
> 
>      u.ci.~C();
> 
>    else
> 
>      u.cc.~C();
> 
> }
> 
> $ clang++ prog.cpp unk.cpp
> 
> /tmp/prog-bfa5e6.o: In function `D::U::U(int)':
> 
> prog.cc:(.text._ZN1D1UC2Ei[_ZN1D1UC2Ei]+0x3e): undefined reference to 
> `C<int>::~C()'
> 
> clang-11: error: linker command failed with exit code 1 (use -v to see 
> invocation)
> 
> 
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-- 
Nathan Sidwell