`Tracking`: F# Hints

[psfinaki]

Note
This is a "meta" issue for tracking purposes since GitHub does not support special types of issues.

Supersedes #10289.

We'll be introducing a feature called F# hints. It is inspired by C# inline hints but will do more! The feature is going to be built on top of the dedicated Roslyn API.

This will supersede the experimental CodeLens feature that is current present in Visual Studio. The CodeLens brand in F# is planned to do the same as in other languages, i.e. show references, test coverage and so on (details here).

The plan is to gradually add different hints and make them configurable. Here is the proposed roadmap:

• Implement inline type hints for F# #14158 (experimental)
• Implement parameter name inline hints for F# #14174 (experimental)
• Remove CodeLens in its current form: Remove F# Lens #14256
• Add parameter name hints for methods #14259
• Don't show parameter name hints when they coincide with argument names #14447
• Move out of the experimental mode to the preview mode
• Consider showing inline hints to the right side of the cursor #14385
• Don't show parameter name hints for some built-in types #14448
• Make Type Hints less intrusive #14382
• Add type hints for the return type of function or member #14379
• Implement click-to-show behavior for the hints #14260
• Add tooltips for the hints #14268
• Don't show hint for a field name when it coincides with the variable name #15157
• Move out of the preview mode
• Implement granular control for F# hints #15131
• Implement signature hints
• Implement pipeline hints

Bugs:

• Type hints break for some tuple cases #14269
• Type Hints showing unsolved type in for expression #14393
• Type hints show redundant info in SRTP #14400
• Inline parameter name hints work weirdly with indexes #14401
• Wrong type hint for a module value containing a lambda #14378
• Incorrect and superfluous parameter hints in methods with optional parameters #14459
• Incorrect hints for CustomOperations in a computation expression #14460
• Hints throw exception #14885
• Parameter name hints in VS get somewhat mangled with nested function calls #15138
• VS counts hints into line length #15576
• Inline parameter name hints work weirdly with slices #15994