erichkeane wrote:
> @erichkeane thanks a lot for the clarification. I think I have a hang of it
> now- I was kinda confused before. Now, my approach is to look through
> DiagnosticXKinds.td files -> check for a `select` with a significant number
> of items -> check its diagnostic ID -> grep the lib directory with this ID
> and find the uses of the diagnostic -> see if it’s up for replacement (caller
> has a lot of magic numbers/an enum made just for it).
>
Yeah, that seems like a good strategy.
> Now I wanted to ask - what do you consider a lot - 3 or more uses with magic
> numbers?
I don't have a 'hard' number here. When I was looking for a few to demo it
with, I just found ones where it was 'most' or 'all' uses.
>
> For a `select` with a significant number of items, I’m thinking of going with
> 4 or more items as it seems reasonable. I was also looking through the
> codebase using this heuristic exposed a lot more for replacement (rather than
> 5 which I had in mind before).
>
Another time I don't have a 'hard' number. It is a bit of a balance between 'a
lot of work' and 'transform enough of the uses that it improves readability'.
If 4 gives a good number of candidates, that is probably a good place to start.
> Also could you just brief me through the process of a change. I know the .td
> files are used to generate header files. So do I have to change the select to
> an enum_select first in the .td files and then build and then reference the
> generated enum option in the caller (e.g. diag::MemClassWork::AliasDecl) and
> then rebuild.
Yes, this would be the first/second step.
> The thing about this is that the build would probably fail the first time as
> the callers will still make use of the magic numbers.
Magic numbers will still compile and work. The version of `Diag`'s operator
`<<` that this calls is still the one that takes an integral value. So adding
`enum_select` to something, as long as you don't change the order/number of
elements, shouldn't break anything.
>I also found an enum declared just for a select that was already in a header
>file. For this case, I just remove this declaration right? And then replace
>the select. I guess I’m just confused about the whole header generation
>process - where the new enums would live since the relevant header files
>already exist before a build (e.g Sema.h, Decl.h) and since we’re making
>changes to .td files which are the header generators. Kinda new to clang stuff
>so forgive me for these questions 😅
Yes, you'd want to remove the old ones. Tablegen will create the enums in the
file `ClangDiagnostic${component}Enums.inc` I think, so search your build
directory and you'll see where those are.
https://github.com/llvm/llvm-project/pull/130868
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