AaronBallman wrote: > > > > I guess the general question is - is it acceptable to have the Scanner > > > > operating in a language standard different than the passed in language > > > > mode and different than the compiler language standard? > > > > > > > > > I think that is acceptable. It is kinda hacky, but the lexer and > > > preprocessor are largely independent of the language and the standard. > > > When they do depend on those settings, taking the union of the features > > > and letting the compiler trim it down is still a perfectly sound thing to > > > do. > > > > > > You can certainly construct cases where the different lexing rules in > > different language modes allow you to detect which language you're in from > > within the preprocessor ([1](https://eel.is/c++draft/diff.cpp11.lex) > > [2](https://eel.is/c++draft/diff.cpp14.lex#2) > > [3](https://eel.is/c++draft/diff.cpp03.lex#1)) or where enabling more > > language mode flags may reject valid code. It may be good enough for what > > the scanner is trying to do, but I think it's a stretch to say that it's > > sound. > > +1; it's definitely not sound to go this approach, though it may work well > enough in practice to be worth the tradeoff. That said, I think the behavior > of the dependency scanner ignoring the language options used is actually kind > of problematic, unless I'm misunderstanding something. This means command > line options that impact dependency scanning may fail (for example, the user > might enable SYCL or OpenMP on the command line and that may have different > dependencies, trigraph support may be important for things like `??=include`, > freestanding vs not impacts which preprocessor macros are predefined, etc. > How do we handle that sort of stuff, or do we just ignore it?
Ping @jansvoboda11 https://github.com/llvm/llvm-project/pull/93753 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
