r374135 - [c++20] P1152R4: warn on any simple-assignment to a volatile lvalue

[Stephan Bergmann via cfe-commits]

On 09/10/2019 04:04, Richard Smith via cfe-commits wrote:
> Author: rsmith
> Date: Tue Oct  8 19:04:54 2019
> New Revision: 374135
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=374135&view=rev
> Log:
> [c++20] P1152R4: warn on any simple-assignment to a volatile lvalue
> whose value is not ignored.
> 
> We don't warn on all the cases that are deprecated: specifically, we
> choose to not warn for now if there are parentheses around the
> assignment but its value is not actually used. This seems like a more
> defensible rule, particularly for cases like sizeof(v = a), where the
> parens are part of the operand rather than the sizeof syntax.
> 
> Modified:
>      cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>      cfe/trunk/include/clang/Sema/Sema.h
>      cfe/trunk/lib/Sema/SemaExpr.cpp
>      cfe/trunk/lib/Sema/SemaExprCXX.cpp
>      cfe/trunk/test/SemaCXX/deprecated.cpp
>      cfe/trunk/www/cxx_status.html

Oh, I should probably have commented here on the mailing list rather 
than at 
<https://github.com/llvm/llvm-project/commit/4a6861a7e5b59be24a09b8b9782255d028e7aade#commitcomment-35540755>:

I assume the scenario at 
<https://gitlab.gnome.org/GNOME/glib/merge_requests/1170> "Avoid C++20 
deprecated assignment to volatile",

   (void) (0 ? *(location) = (result) : 0);

where *(location) is of (non-class) volatile type, is a true positive 
that we indeed want to warn about?