[PATCH] D18649: [clang-tidy] cppcoreguidelines-interfaces-global-init

[Alexander Kornienko via cfe-commits]

alexfh added a comment.

In http://reviews.llvm.org/D18649#390862, @courbet wrote:

> In http://reviews.llvm.org/D18649#389363, @alexfh wrote:
>
> > Thank you for working on the new clang-tidy check!
> >
> > We usually recommend authors to run their checks on a large code base to ensure it doesn't crash and doesn't generate obvious false positives. It would be nice, if you could provide a quick summary of such a run (total number of hits, number of what seems to be a false positive in a sample of ~100).
>
>
> The tool generated 20k positives on our codebase. On a sample of 100, there are:
>
> - 8 instances of the same exact code structure that's just wrong: const string var = FLAGS_some_flag + "some_sufix";
> - 8 false positives.
> - 84 possible issues. (interestingly 6 of these are from premature use of variations of "extern char* empty_string;"
>
>   The false positives fall into 3 categories:
> - 3 variations of: ``` extern int i; static const int* pi = &i;  // diag ```


Should we warn at all when only an address of a global variable is used?

> // Then pi is dereferenced later, once i is intialized. 

>  Public example of this: https://github.com/python-git/python/blob/py3k/Objects/dictobject.c#L2027

> 

> 2. 3 variations of: ``` // .h class A { static const int i = 42; }; // .cc int A::i;  // diag ```


Looks like we have all information to fix this kind of a false positive.

> 

> 

> 3. 2 variations of: ``` // .h class A { static int i; static int j; }; // .cc int A::i = 0; int A::j = i;  // diag ```


ditto


http://reviews.llvm.org/D18649