Re: [C++ Patch] PR 80955 (Macros expanded in definition of user-defined literals)

[Mukesh Kapoor <mukesh dot kapoor at oracle dot com>]

On 10/20/2017 11:00 AM, Mukesh Kapoor wrote:
> Hi,
>
> On 10/20/2017 10:45 AM, Nathan Sidwell wrote:
> > On 10/20/2017 12:37 PM, Mukesh Kapoor wrote:
> > > Hi,
> > >
> > > This patch fixes https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80955.
> > > Handle user-defined literals correctly in lex_string(). An empty 
> > > string followed by an identifier is
> > > a valid user-defined literal. Don't issue a warning for this case.
> >
> > a) why do we trigger on the definition of the operator function, and 
> > not on the use site?
>
> Actually, the current compiler issues an error (incorrectly) at both 
> places: at the definition as well as at its use.
>
> > b) Why is the empty string special cased?  Doesn't the same logic 
> > apply to:
> >
> > int operator "bob"_zero (const char *, size_t) { return 0;}
>
> This is not a valid user-defined literal and is already reported as an 
> error by the compiler. After my changes it's still reported as an error.
> The empty string immediately followed by an identifier is a special 
> case because it's a valid user-defined literal in C++. ""_zero is a 
> valid user-defined literal.

Sorry, I used incorrect terminology here. An empty string immediately 
followed by an identifier is a valid name for a literal operator; 
""_zero is a valid name for a literal operator.

Mukesh

> Mukesh
>
> > (that'd be a syntactic error in the C++ parser of course)
> >
> > nathan