If we find a blanket impl for `Trait` but we're matching on an object `Trait`, prefer the object (I think we could perhaps go either way, but this seems safer). Also give a nice error for attempts to manually `impl Trait for Trait`, since they will be ineffectual.
This fixes the problems around ambiguity ICEs relating to `Any` and `MarkerTrait` that were cropping up all over the place. There may still be similar ICEs reported in #21756 that this PR does not address.
Fixes#24015.
Fixes#24051.
Fixes#24037.
Fixes#23853.
Fixes#21942.
cc #21756.
cc @alexcrichton (this fixes crates.io)
r? @aturon
traits.md said:
If we add a `use` line right above `main` and make the right things public,
everything is fine:
However, the use line was actually placed at the top of the file instead. Move
the use line to right above main. That also makes the example more evocative
of cases where the module is defined in a separate file.
`Trait`, prefer the object. Also give a nice error for attempts to
manually `impl Trait for Trait`, since they will be ineffectual.
Fixes#24015.
Fixes#24051.
Fixes#24037.
Fixes#23853.
Fixes#21942.
cc #21756.
The current help string ("space separated list") suggests that
`--passes "pass1 pass2"` is expected; the correct usage is
`--passes pass1 --passes pass2`.
- Added missing reverse versions of methods
- Added [r]matches()
- Generated the string pattern iterators with a macro
- Added where bounds to the methods returning reverse iterators
for better error messages.
- Functions in parser.rs return PResult<> rather than panicing
- Other functions in libsyntax call panic! explicitly for now if they rely on panicing behaviour.
- 'panictry!' macro added as scaffolding while converting panicing functions.
(This does the same as 'unwrap()' but is easier to grep for and turn into try!())
- Leaves panicing wrappers for the following functions so that the
quote_* macros behave the same:
- parse_expr, parse_item, parse_pat, parse_arm, parse_ty, parse_stmt
I ran across a comma splice.
I didn't set the "note:" off inside parenthesis. I looked around in other places and saw it both ways, but without surrounding parenthesis seemed to be the more common convention followed elsewhere in the docs. Let me know if you have an overriding preference about that and I'll change it.
r? @steveklabnik
This syncs the _Crates and Modules_ chapter of the book with current output:
* the runs are supposed to be in the project’s directory,
* `rustc` has slightly different error messages (and things like macro line:col numbers),
* Cargo now compiles things into `target/debug`.
