[cfe-dev] [cfe-commits] [PATCH] Re: Interest in a -Wusing-namespace-in-headers?

[Sebastian Redl]

On 18.03.2011, at 17:15, Douglas Gregor wrote:

> 
> On Mar 17, 2011, at 11:05 AM, Elliot Glaysher (Chromium) wrote:
> 
>> Adds a -Wheader-hygiene warning for warnings that should only trigger
>> in #included files.
>> 
>> The first -Wheader-hygiene check is to make sure a using directive
>> isn't placed in the global context in a header.
>> 
>> On Wed, Mar 16, 2011 at 6:15 PM, Douglas Gregor <dgregor at apple.com> wrote:
>>> You don't need to perform the getDiagnosticLevel() check yourself, because the diagnostic system will handle warning suppression itself.
>>> 
>>> However, I do suggest performing the CurContext->getDeclKind() == Decl::TranslationUnit check before the isFromMainFile() check, since the former is cheaper.
>> 
>> Done.
> 
> Committed in r127881, thanks!

Do we want to warn about this?

extern "C++" {
  using namespace foo;
}

Because the fact that extern blocks are decl contexts has bitten me before, and the above suggestion would fall prey to the same issue.

Sebastian