Fortran 2018 implementation status

[h-vetinari]

I'm wondering what's the state of the Fortran 2018 implementation (very high-level tracking like gcc's status page). Maybe such a tracker already exists, but is not public? Maybe - as the name suggests 😉 - it's already (almost) finished?

I haven't found such an overview except some more granular projects under the flang-compiler organisation, a mention of "References are to the 12-2017 draft of the Fortran 2018" in the documentation, and the following quote from the flang roadmap [my bold]:

We believe that starting in 2020, F18 will replace the current Flang as a complete implementation of Fortran 2018.

Note that flang has such a status page for Fortran 2008. If f18 does not yet fully support that, my question (about implementation status) extends to 2008 as well.

Presumably, such a status overview would also be useful after merging into LLVM (cf. their C++ page).

[eugeneswalker]

I'm also interested in this!

[kiranchandramohan]

Various parts of the compiler are in different stages of completion. A horizontal implementation approach was chosen, hence it will not be possible to provide a status page for Fortran 2018. But the implementation is based on the Fortran 2018 standard.

The following status is based on my observation as a member of the Flang/F18 community. Someone else might be able to provide a better answer.

Parsing for Fortran 2018 and OpenMP 4.5 : Complete
Semantic checks : Nearing completion
High level IR (FIR) : In progress. Uses MLIR. Lowering from parse tree to FIR should land soon.
Runtime (math) : Will use the pgmath library available with current Flang project
Runtime (I/O) : In progress
Runtime (memory) : Started
Runtime (Rest) : Not started

[h-vetinari]

@kiranchandramohan: Various parts of the compiler are in different stages of completion. A horizontal implementation approach was chosen, hence it will not be possible to provide a status page for Fortran 2018. But the implementation is based on the Fortran 2018 standard.

Thanks for the answer. I don't understand what you mean with the above. Horizontal or not, either a given feature is either done or not...? And from the list of features (or changes) from F2008 to F2018, one could record what's still open (or partially done / WIP / etc.).

But OK, maybe it's too early in the process to have a list like that, and all the bits and pieces need to move into place first.

[kiranchandramohan]

At the moment everything is a work in progress since there is no FIR/LLVM codegen in the master branch. So we can only mark all features as in progress.
Yes, you are right that it is a bit early to have a list like that.

[eugeneswalker]

I had heard the plan was to get f18 merged into llvm by end-of-April. Is this incorrect? Is there a target date for this?

[kiranchandramohan]

I believe it is mostly ready for the llvm merge. The date will hopefully be fixed during the Flang/F18 community call on Monday.
If you are interested, the call details are below. Copied from Gary's biweekly minutes.
"Hal Finkel hosts this call on Bluejeans, Mondays 8:30 Pacific Time, on the weeks alternating with regular Flang biweekly call. The notes for all these calls can be found in Google Docs here.
Meeting URL: https://bluejeans.com/625064848?src=join_info
Meeting ID: 625 064 848
Want to dial in from a phone? Dial one of the following numbers:
+1.408.317.9254 (US (San Jose))
+1.866.226.4650 (US Toll Free)
(see all numbers - https://www.bluejeans.com/premium-numbers)
Enter the meeting ID and passcode followed by #"

[eugeneswalker]

@kiranchandramohan Are the google docs you mention above available online somewhere for public access? I am interested in the status of f18 driver.

[kiranchandramohan]

Google docs can be accessed with the following link.
https://docs.google.com/document/d/1Z2U5UAtJ-Dag5wlMaLaW1KRmNgENNAYynJqLW2j2AZQ/edit#heading=h.vpxs8lkuxy79

@eugeneswalker You can find the latest discussion in the following review.
https://reviews.llvm.org/D79092

@h-vetinari can you close this issue if you are happy with the answer provided before?

[h-vetinari]

@kiranchandramohan
I understand that the project might not be ready to create such an overview of the F2018-compatibility yet, but I don't think that this means that this issue should automatically be closed? This is more a longterm goal - to track implementation status relative to the most current standard (even after F2018)...