On Thu, May 30, 2019 at 6:59 PM Joseph Myers <jos...@codesourcery.com> wrote: > > On Thu, 30 May 2019, Alex Henrie wrote: > > > At this point I think I'm convinced that any attribute that applies to > > a function should also be allowed on a function pointer without any > > warnings. We can start by turning off the warnings for the "fndecl" > > attributes and then clean up the other attributes as time goes on. > > This is inherently a property of the attribute in question. The issue is > not whether it applies to function pointers; it's whether it applies to > function types. > > For example, the "section" or "alias" attributes are attributes that apply > to a declaration, but not a type. Because they apply to variables as well > as functions, they are meaningful on function pointers - but the meaning > is *not* the same as applying them to the pointed-to function. > > The "flatten" attribute, however, seems only meaningful for functions, not > variables, not function types and not function pointers. > > We should try to work out for each attribute exactly what construct it > appertains to - which for many but not all function attributes is indeed > the type of the function rather than the function itself. Then move to > making such attributes work on types. But for attributes such as > "flatten" that logically appertain to the declaration not its type, we > should continue to diagnose them on function pointers or types.
In Wine we need a way to (without warnings) put ms_hook_prologue into a macro that is applied to functions, function pointers, and function pointer typedefs. It sounds like you're saying that you will not accept a patch that silences or splits off warnings about using ms_hook_prologue with function pointers and function pointer typedefs. So how do you think Wine's problem should be solved? It seems to me that any information about the target of a function pointer, even the flatten attribute or the ms_hook_prologue attribute, provides information that could be useful for optimizing the code around the indirect function call. That sounds like a compelling argument for allowing these attributes in more places without warnings. -Alex
