[PATCH] D26667: Teach clang that 'sv' is a fine literal suffix

[Richard Smith via cfe-commits]

rsmith added inline comments.


================
Comment at: lib/Lex/LiteralSupport.cpp:768
       .Cases("il", "i", "if", true)
+      .Case("sv", true)
       .Default(false);
----------------
aaron.ballman wrote:
> mclow.lists wrote:
> > aaron.ballman wrote:
> > > malcolm.parsons wrote:
> > > > aaron.ballman wrote:
> > > > > mclow.lists wrote:
> > > > > > malcolm.parsons wrote:
> > > > > > > This is in `NumericLiteralParser::isValidUDSuffix()`.
> > > > > > > 
> > > > > > > If a change is needed for `"sv"`, wouldn't it be in `StringLiteralParser`?
> > > > > > Would it be?  I don't know.  `"s"` appears here, which is used for both 'string' and 'seconds'.
> > > > > This function is used by the numeric literal parser, and so `sv` does not make sense there. It's also used by SemaDeclCXX.cpp in `CheckLiteralOperatorDeclaration()`, where this change would make sense.
> > > > > 
> > > > > I was asking about test cases; I was wondering what problem this was trying to solve. I suspect you want to modify `CheckLiteralOperatorDeclaration()` rather than `NumericLiteralParser`.
> > > > `s` for `std::string` seems to be handled in `Lexer::LexUDSuffix()`:
> > > > 
> > > > ```
> > > >             IsUDSuffix = (Chars == 1 && Buffer[0] == 's') ||
> > > >                          NumericLiteralParser::isValidUDSuffix(
> > > >                              getLangOpts(), StringRef(Buffer, Chars));
> > > > ```
> > > Good catch, there too (I haven't done a complete tour to see where else may need changing).
> > That's really interesting; since I made the change I described and tested it and it works fine:
> > 
> >     constexpr std::string_view sv = "1234"sv;
> >     constexpr std::string_view sv = "ACBQ"sv;
> > 
> > "works fine" in this case means "compiles w/o error"
> > 
> > (Not that I'm disputing that there might be a better place for this)
> You modified `NumericLiteralParser::isValidUDSuffix()`, which is called by the code @malcolm.parsons posted. So the changes will work, but the design is wrong since the UD suffix has nothing to do with parsing numeric literals.
We should add a `StringLiteralParser::isValidUDSuffix` and use it from `Lexer::LexUDSuffix` (and anywhere else that wants to know).


https://reviews.llvm.org/D26667