[flang-commits] [flang] [Flang] Add a Fortran Standards Support doc (PR #132195)

[Peter Klausler via flang-commits]

klausler wrote:

> Thanks @klausler for the info. I will add sections for Fortran 2018 and 2023.
> 
> > > > I guess we should see if we can get a list of updates from J3/WG5 for 2018 and 2023 Fortran to populate the list.
> > > 
> > > 
> > > I am leaving this for a future patch. 2023 should be fairly straightforward. I do not have the data for Fortran 2018.
> > 
> > 
> > f18 has all of F'2018 except `coshape` intrinsic lowering.
> 
> Is there a specific reason you called out the `coshape` intrinsic? I see the other coarray extensions in Fortran 2018 hitting TODOs in lowering.

I skimmed my notes of F'2018 additions and `coshape` stood out as the one item that I know isn't fully supported.   If other coarray features from F'2018 are incomplete, please note them as well.  Some were added as part of a TS between F'2008 and F'2018 so that makes them a little harder to find.

> 
> > F'2023 support is completely absent and nobody is working on it.
> 
> A few of them seem to have support -> Allow much longer statement lines and overall statement length -> selected_logical_kind -> do-concurrent reduction

Fair enough.  The lack of limits on continuation lines and statement length have always been present, so I never thought of them as new features.  But F'2023 was a minor revision, and includes some weird features (e.g. `@` subscripts) and a breaking change that don't appear in any compiler or (obviously) application yet, and that probably won't get any attention from me -- although I did add a portability warning for the breaking change.  If you add a section for F'2023, it's going to be largely unpopulated.

https://github.com/llvm/llvm-project/pull/132195