This PR adjusts the "try this" widget to be rendered as a widget message
under 'Messages', not a separate widget under a 'Suggestions' section.
The main benefit of this is that the message of the widget is not
duplicated between 'Messages' and 'Suggestions'.
Since widget message suggestions were already implemented by @jrr6 for
the new hint infrastructure, this PR replaces the old "try this"
implementation with the new hint infrastructure. In doing so, the
`style?` field of suggestions is deprecated, since the hint
infrastructure highlights hints using diff colors, and `style?` also
never saw much use downstream. Additionally, since the message and the
suggestion are now the same component, the `messageData?` field of
suggestions is deprecated as well. Notably, the "Try this:" message
string now also contains a newline and indentation to separate the
suggestion from the rest of the message more clearly and the `postInfo?`
field of the suggestion is now part of the message.
Finally, this PR changes the diff colors used by the hint infrastructure
to be more color-blindness-friendly (insertions are now blue, not green,
and text that remains unchanged is now using the editor foreground color
instead of blue).
### Breaking changes
Tests that use `#guard_msgs` to test the "Try this:" message may need to
be adjusted for the new formatting of the message.
This PR improves the error messages produced by the `split` tactic,
including suggesting syntax fixes and related tactics with which it
might be confused.
Note that, to avoid clashing with the new error message styling
conventions used in these messages, this PR also updates the formatting
of the message produced by `throwTacticEx`.
Closes#6224
This PR allows `simp` to recognize and warn about simp lemmas that are
likely looping in the current simp set. It does so automatically
whenever simplification fails with the dreaded “max recursion depth”
error fails, but it can be made to do it always with `set_option
linter.loopingSimpArgs true`. This check is not on by default because it
is somewhat costly, and can warn about simp calls that still happen to
work.
This closes#5111. In the end, this implemented much simpler logic than
described there (and tried in the abandoned #8688; see that PR
description for more background information), but it didn’t work as well
as I thought. The current logic is:
“Simplify the RHS of the simp theorem, complain if that fails”.
It is a reasonable policy for a Lean project to say that all simp
invocation should be so that this linter does not complain. Often it is
just a matter of explicitly disabling some simp theorems from the
default simp set, to make it clear and robust that in this call, we do
not want them to trigger. But given that often such simp call happen to
work, it’s too pedantic to impose it on everyone.
