@Kha Note that I had to write the weird pattern
```
match_syntax stx with
| `(notation:$prec $items* => $rhs) => expandNotationAux stx prec items rhs
| `(notation $noprec* $items* => $rhs) => expandNotationAux stx none items rhs
| _ => Macro.throwUnsupported
```
with the weird `$noprec*` to match the case where the optional
precedence is not provided. I realized this is not a bug, but
I guess most users will be puzzled by this behavior. If we had a kind
for `notationItem`, I would be able to write
```
`(notation $items:notationItems* => $rhs)
```
@Kha I implemented the solution 1 I described at Zulip.
I also tried to document the issue, and made sure test
`choiceMacroRules` fail if the bug is reintroduced.
@Kha Could you please double check these modifications.
I added a no-op for `checkRbpLt`. It is used at the `Sort` and `Type`
parsers.
As I described in previous commits, the `checkRBPGreater` comment and
implementation were misleading. It was actually succeeding when the
rbp was less than or equal to the given parameter. So, it was renamed
to `checkRbpLe`. So, is the depArrow parenthesizer ok? I did not check.
I updated the PPRoundtrip.lean.expected.out to make sure the tests
succeed, but we should revise it if there is a problem with the
modifications at Parenthesizer.lean
@Kha It is not clear to me why I had to change the following line
```
-syntax term ">>>" term : foo
+syntax term:1 ">>>":1 term : foo
```
The test breaks without it.
@Kha I tried to fix a few issues with private names. The new test
tries to cover them. If you have more, please create an issue.
1- Scoping. A private declaration should shadow one in a previous scope.
2- We should not be able to define the same `private` in the same
module more than once.
```
private def x := 10
private def x := "hello" -- should produce error here
```
3- Dot-notation should work with private declarations in the module
where they were defined.
4- The following should work
```
namespace N
private def x := 10
end N
#check N.x
```
5- The following should **not** work
```
def y := 10
private def y := "hello" -- produce error
private def z := 10
def z := "hello" -- produce error
```
BTW, I am happy to change this behavior. I just mimicked C's
behavior for `static`.
It is not clear whether the following should work or not.
```
namespace N
private def b := 10
end N
open N
#check b
```
