[PATCH] D31343: Add an attribute plugin example

[Jasmin Fazlic via Phabricator via cfe-commits]

Jasmin added a comment.

Hello John!

I was encouraged by Erich after a talk I had with him and Aaron on IRC to contact you about an use case for this plugin.

I wanted to use user-specified/unknown attributes to annotate code and was told that they are not propagated through
the AST and therefore it is not possible at the moment to use them for that purpose. Aaron's and Erich's idea was to
allow kind of no-op attributes in the plugin so that the compiler would not issue a warning about the unknown attribute.
This would be helpful for the user being able to define a list of attributes the user knows and expects, so that a compilation
would not be spammed unnecessarily and misspelled attributes would still stand out.

Being able to get the cursor or displayName of the attribute would essentially be enough to use it in tooling.

We can use __attribute__((annotate(smth))) at the time being to achieve the same goal, but it is much more writing to do
and also vendor specific. Being able to do the same with attributes would give them a real purpose, other than having
to be accepted and not causing an error. Also they have to be supported by the language and we don't have to use
macros to annotate the code.

To summarize it would be nice to have:

- user supplied unknown attributes to suppress a warning
- unknown attributes propagated in the AST

I hope I summarized this correctly and could get through the gist of this idea.

Looking forward to hearing from you.

Best regards, Jasmin


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  https://reviews.llvm.org/D31343/new/

https://reviews.llvm.org/D31343