On Fri, May 31, 2019 at 11:50:47AM -0400, Marek Polacek wrote:
> On Thu, May 30, 2019 at 05:28:47PM -0600, Martin Sebor wrote:
> > On 5/28/19 3:30 PM, Sean Gillespie wrote:
> > > This adds a new warning, -Wglobal-constructors, that warns whenever a
> > > decl requires a global constructor or destructor. This new warning fires
> > > whenever a thread_local or global variable is declared whose type has a
> > > non-trivial constructor or destructor. When faced with both a constructor
> > > and a destructor, the error message mentions the destructor and is only
> > > fired once.
> > >
> > > This warning mirrors the Clang option -Wglobal-constructors, which warns
> > > on the same thing. -Wglobal-constructors was present in Apple's GCC and
> > > later made its way into Clang.
> > >
> > > Bootstrapped and regression-tested on x86-64 linux, new tests passing.
> >
> > I can't tell from the Clang online manual:
> >
> > Is the warning meant to trigger just for globals, or for all
> > objects with static storage duration regardless of scope (i.e.,
> > including namespace-scope objects and static locals and static
> > class members)?
> >
> > "Requires a constructor to initialize" doesn't seem very clear
> > to me. Is the warning intended to trigger for objects that
> > require dynamic initialization? If so, then what about dynamic
> > intialization of objects of trivial types, such as this:
> >
> > static int i = std::string ("foo").length ();
> >
> > or even
> >
> > static int j = strlen (getenv ("TMP"));
>
> The warning is not meant to diagnose these. But I do agree that the
> documentation for the new warning should be improved.
I was partially wrong: if i/j are at file scope, then the warning triggers.
But if i/j are in a function, then it doesn't warn.
My apologies.
Marek
