This PR scans the environment for viable replacements for a dotted
identifier (like `.zero`) and suggests concrete alternatives as
replacements.
## Example
```
#example .zero
```
Error message:
```
Invalid dotted identifier notation: The expected type of `.cons` could not be determined
```
Additional hint added by this PR:
```
Hint: Using one of these would be unambiguous:
[apply] `BitVec.cons`
[apply] `List.cons`
[apply] `List.Lex.cons`
[apply] `List.Pairwise.cons`
[apply] `List.Perm.cons`
[apply] `List.Sublist.cons`
[apply] `List.Lex.below.cons`
[apply] `List.Pairwise.below.cons`
[apply] `List.Perm.below.cons`
[apply] `List.Sublist.below.cons`
[apply] `Lean.Grind.AC.Seq.cons`
```
## Additional changes
This PR also brings several related error message descriptions and code
actions more in line with each other, changing several "Suggested
replacement: " code actions to the more common "Change to " wording, and
sorts suggestions obtained from searching the context by the default
sort for Names (which prefers names with fewer segments).
This PR gives suggestions based on the currently-available constants
when projecting from an unknown type.
## Example: single suggestion in namespace
This was the originally motivating example, as the string refactor led
to a number of anonymous-lambda-expressions with `Char` functions that
were no longer recognized as such.
```lean4
example := (·.isWhitespace)
```
Before:
```
Invalid field notation: Type of
x✝
is not known; cannot resolve field `isWhitespace`
```
The message is unchanged, but this PR adds a hint:
```
Hint: Consider replacing the field projection `.isWhitespace` with a call to the function `Char.isWhitespace`.
```
## Example: single suggestion in namespace
```lean4
example := fun n => n.succ
```
Before:
```
Invalid field notation: Type of
n
is not known; cannot resolve field `succ`
```
The message is unchanged, but this PR adds a hint:
```
Hint: Consider replacing the field projection with a call to one of the following:
• `Fin.succ`
• `Nat.succ`
• `Std.PRange.succ`
```
This PR improves the error messages produced by invalid projections and
field notation. It also adds a hint to the "function expected" error
message noting the argument to which the term is being applied, which
can be helpful for debugging spurious "function expected" messages
actually caused by syntax errors.
---------
Co-authored-by: Joachim Breitner <mail@joachim-breitner.de>
This PR clarifies the invalid field notation error when projected value
type is a metavariable.
Co-authored-by @sgraf812.
---------
Co-authored-by: Sebastian Graf <sg@lean-fro.org>
