Status of explicit conversion operators and nullptr

Clang Frontend
1

Hello,

according to <http://clang.llvm.org/cxx_status.html&gt;, explicit conversion operators are currently
not really functional:

No name mangling; ASTs don't contain calls to conversion operators

I just tried using them and to my delight they worked: Not only did the code compile (after I inserted
the missing explicit casts), the resulting application ran without a hitch. To whomever implemented it:
THANK YOU! :slight_smile:

The code I used them in was:

template <typename T, unsigned int FractBits>
class Fixed {
  ...

  // Convert to a float
  explicit inline operator float() const;

  // Convert to any integer
  template <typename U, typename std::enable_if<std::is_integral<U>::value, int>::type = 0>
  explicit inline operator U() const;
};

I therefore think that the above status page should be updated at least to yellow ("many examples
work").

The same goes for nullptr support: I have been using it successfully for weeks now (almost) without
problems. Code generation most certainly isn't "broken". __has_feature(cxx_nullptr) also evaluates
to "1".

Are these assessments correct (and should I send a patch for the status page), or am I overlooking
something?

With many thanks in advance,
Jonathan

2

Hi All,

I am seeing three new failures today after I did an llvm update and built it for apple-darwin.

Failing Tests (3):
    Clang :: CodeGenCXX/vtable-debug-info.cpp
    Clang :: CodeGenObjC/debug-info-getter-name.m
    Clang :: Driver/hello.c

- Fariborz

3

I don't believe that explicit conversions are fully implemented. At the very least, we need an audit + test cases for all of the places where we look at implicit conversions, to ensure that we're properly enabling/disabling explicit conversion functions at the right times.

nullptr is basically fully implemented. The only remaining issue I know of is that a thrown std::nullptr won't be caught as a T*, which is rather minor and might be more of a runtime issue . I'd appreciate it if you could send a patch for the status page!

  - Doug

4

It looks like this might be related to compiling clang with gcc vs. with clang. Seems that if you compile the latest clang with gcc, the resulting compiler has problems.

Jonathan

5

Try again with r135594 :slight_smile:

- Ben

6

Try updating to r135594 or later.

-Eli

7

Thanks! That fixes it for me.

Jonathan

8

Thanks to all who responded. TOT has since fixed the bug.

- Fariborz