llvm dev - Nov 2016 - RFC: Constructing StringRefs at compile time

On 28 November 2016 at 20:51, Zachary Turner via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> The basic idea here is that you introduce a StringLiteral class and
anywhere
> you want to use a global constructor, you make sure to declare a constexpr
> array instead of a normal array, and you make it of type StringLiteral.
I prefer constexpr llvm_strlen() over StringLiteral because it doesn't
require code changes outside StringRef - all StringRefs constructed
from a literal can benefit.  But there are concerns about MSVC.
I prefer StringLiteral over UDL because the type requires code
changes, but the values don't.
I prefer StringLiteral over explicit StringRef constructor because it's
safer.

-- 
Malcolm Parsons

I don't like the llvm_strlen approach as it is incompatible with
std::string_view which we may eventually move to.  StringLiteral will still
interoperate nicely

On Tue, Nov 29, 2016 at 2:20 AM Malcolm Parsons <malcolm.parsons at
gmail.com>
wrote:
> On 28 November 2016 at 20:51, Zachary Turner via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
> > The basic idea here is that you introduce a StringLiteral class and
> anywhere
> > you want to use a global constructor, you make sure to declare a
> constexpr
> > array instead of a normal array, and you make it of type
StringLiteral.
>
> I prefer constexpr llvm_strlen() over StringLiteral because it doesn't
> require code changes outside StringRef - all StringRefs constructed
> from a literal can benefit.  But there are concerns about MSVC.
> I prefer StringLiteral over UDL because the type requires code
> changes, but the values don't.
> I prefer StringLiteral over explicit StringRef constructor because it's
> safer.
>
> --
> Malcolm Parsons
>
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On 29 November 2016 at 16:18, Zachary Turner <zturner at google.com>
wrote:
> I don't like the llvm_strlen approach as it is incompatible with
> std::string_view which we may eventually move to.
In what way is it incompatible?

constexpr StringRef(const char* s) : Data(s), Length(llvm_strlen(s)) {}
is equivalent to
constexpr string_view(const char* s) : Data(s),
Length(std::char_traits<char>::length(s)) {}

-- 
Malcolm Parsons