[cfe-dev] [clangd-dev] RFC: add RecoveryExpr to represent invalid constructs in AST

[Dmitry Kozhevnikov via cfe-dev]

This would be great for tooling, thank you!

 - what's the type of the expression when we can't guess? (IntTy in the
> patch)
>

I think some kind of synthetic “unknown type”, not convertible to anything,
would be helpful here - so it’s guaranteed `foo(bar())` won’t pick an
unwanted overload if `bar()` is a RecoveryExpr, and `foo()` has several
overloads. It might also be somewhat useful in other places - i.e. as a
placeholder for not yet deduced init-lists (it uses VoidTy now IIRC).

It would also be great if the overload set could be captured in the
RecoveryExpr (or does it already? I haven’t look too carefully, sorry) - so
the tools can offset navigation with several targets on a failed overloaded
function call without resorting to dealing with compiler diagnostic
messages - and it might be possible to do features like “parameter info” on
the AST, without reparsing?  Ex: `foo(/* hint possible parameters here from
all available overloads*/);` - now it requires reparsing in code-completion
mode, if I’m not mistaken.

—
Dmitry.

> --
Best regards,
Dmitry Kozhevnikov
CLion Team Lead
JetBrains
http://www.jetbrains.com
The Drive To Develop
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