Re: [PATCH] C/C++: more stdlib header hints (PR c/81404)

[Joseph Myers <joseph at codesourcery dot com>]

On Tue, 17 Oct 2017, David Malcolm wrote:

> It also adds generalizes some of the code for this (and for the "std::"
> namespace hints in the C++ frontend), moving it to a new
> c-family/known-headers.cc and .h, and introducing a class known_headers.
> This currently just works by scanning a hardcoded array of known
> name/header associations, but perhaps in the future could be turned
> into some kind of symbol database so that the compiler could record API
> uses and use that to offer suggestions e.g.
> 
> foo.cc: error: 'myapi::foo' was not declared in this scope
> foo.cc: note: 'myapi::foo" was declared in header 'myapi/private.h'
> (included via 'myapi/public.h') when compiling 'bar.cc'; did you forget to
> '#include "myapi/public.h"'?
> 
> or somesuch.
> 
> In any case, moving this to a class gives an easier way to locate the
> hardcoded knowledge about the stdlib.
> 
> The patch also adds similar code to the C++ frontend covering
> unqualified names in the standard library, so that rather than just

I'd tend to expect hardcoded standard library knowledge, where it relates 
to symbols present for both C and C++, to be in a common c-family file 
(e.g. listing both C and C++ headers for each symbol, with the possibility 
of some symbols only having a header listed for one C and C++; most C 
symbols would have <foo.h> and <cfoo> listed, but some might be different, 
e.g. wchar_t being a keyword in C++ or clog being completely different in 
the two libraries).  That reduces the chance of a symbol being 
gratuitously listed for one language only when such hints make sense for 
it in both languages.

-- 
Joseph S. Myers
joseph@codesourcery.com