[PATCH] D114714: [C++20][Modules] Add enumerations for partition modules and stream them.

Tue Feb 15 12:37:04 PST 2022

urnathan added inline comments.

================
Comment at: clang/include/clang/Basic/Module.h:109

-    /// This is a C++ Modules TS module interface unit.
+    /// This is a C++ Modules TS or C++20 module interface unit.
     ModuleInterfaceUnit,
----------------
iains wrote:
> urnathan wrote:
> > I think it's confusing to continue to refer to modules-ts modules at this point.  Is that really necessary?
> > The specific confusion here is that does 'ModuleInterfaceUnit' mean one of two different things depending on compilation mode, or is it a single thing with two different names?
> In this case, I re-used the enumeration since the modules-ts / c++20 modules are disambiguated by the -fmodules-ts flag.
> 
> So, yes, the enum value does have two uses depending on compilation mode.  I can amend the comment to try and make this clear, would that help?
> 
> I have been trying not to regress anything for modules-ts (and certainly for clang modules) - if someone makes a decision to retire modules-ts then there is probably a bunch of simplification that could be made.  
> 
> With the extra bit to represent the enumeration, we have more space so we *could* have different names for the modules-ts/C++20 interfaces (although I suspect that will just make more code at the use sites, and would prefer not to go down that route).  
> 
IMHO 'modules-ts' is not a useful thing distinct from 'c++20 modules'.  The semantics of the TS itself were unclear or broken in places, and only resolved once things got into the std (via 1103/Atom).  I think the semantics of '-fmodules-ts' should be the module-specific semantics of C++20 as applied to whatever version of the std being selected (and I'd be fine making it Buyer-Beware for anything before C++20 anyway). 

But, if you don't want to bite that bullet right now, a clarifying note would be helpful.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D114714/new/

https://reviews.llvm.org/D114714