Overhaul `MacArgs`
Motivation:
- Clarify some code that I found hard to understand.
- Eliminate one use of three places where `TokenKind::Interpolated` values are created.
r? `@petrochenkov`
The value in `MacArgs::Eq` is currently represented as a `Token`.
Because of `TokenKind::Interpolated`, `Token` can be either a token or
an arbitrary AST fragment. In practice, a `MacArgs::Eq` starts out as a
literal or macro call AST fragment, and then is later lowered to a
literal token. But this is very non-obvious. `Token` is a much more
general type than what is needed.
This commit restricts things, by introducing a new type `MacArgsEqKind`
that is either an AST expression (pre-lowering) or an AST literal
(post-lowering). The downside is that the code is a bit more verbose in
a few places. The benefit is that makes it much clearer what the
possibilities are (though also shorter in some other places). Also, it
removes one use of `TokenKind::Interpolated`, taking us a step closer to
removing that variant, which will let us make `Token` impl `Copy` and
remove many "handle Interpolated" code paths in the parser.
Things to note:
- Error messages have improved. Messages like this:
```
unexpected token: `"bug" + "found"`
```
now say "unexpected expression", which makes more sense. Although
arbitrary expressions can exist within tokens thanks to
`TokenKind::Interpolated`, that's not obvious to anyone who doesn't
know compiler internals.
- In `parse_mac_args_common`, we no longer need to collect tokens for
the value expression.
Update `ProjectionElem::Downcast` documentation
`ProjectionElem:::Downcast` is used when downcasting to a variant of
an enum or a generator, regardless of the number of variants.
Quick fix for #96223.
This PR is a quick fix regarding #96223.
As mentioned in the issue, others modification could be added to not elide types with bound vars from suggestions.
Special thanks to ``@jackh726`` for mentoring and ``@Manishearth`` for minimal test case.
r? ``@jackh726``
When suggesting to import an item, also suggest changing the path if appropriate
When we don't find an item we search all of them for an appropriate
import and suggest `use`ing it. This is sometimes done for expressions
that have paths with more than one segment. We now also suggest changing
that path to work with the `use`.
Fix#95413
The comment on this function explains that it's a specialized version of
`maybe_whole_expr`. But `maybe_whole_expr` doesn't do anything with
`NtIdent`, so `is_whole_expr` also doesn't need to.
Use reverse postorder in `non_ssa_locals`
The reverse postorder, unlike preorder, is now cached inside the MIR
body. Code generation uses reverse postorder anyway, so it might be
a small perf improvement to use it here as well.
Mitigate impact of subtle invalid call suggestion logic
There's some subtle interaction between inferred expressions being
passed as an argument to fn calls with fewer than expected arguments. To
avoid the ICE, I'm changing indexing operations with `.get(idx)`, but
the underlying logic still needs to be audited as it was written with
the assumption that `final_arg_types` and `provided_args` have the right
length.
Address #96638.
Update `RValue::Discriminant` documentation
`RValue::Discriminant` returns zero for types without discriminant.
This guarantee is already documented for `discriminant_value`
intrinsics which is implemented in terms of `RValue::Discriminant`.
Use source callsite in check_argument_types suggestion
This makes the "remove extra arguement" suggestion valid when the function argument is a macro.
Additionally, this may fix#96225, but the only way I can reproduce that issue is using the playground, so we will need to wait until after this is merged to ensure it's fixed.
Refactor the WriteBackendMethods and ExtraBackendMethods traits
The new interface is slightly less confusing and is easier to implement for non-LLVM backends.
When we don't find an item we search all of them for an appropriate
import and suggest `use`ing it. This is sometimes done for expressions
that have paths with more than one segment. We now also suggest changing
that path to work with the `use`.
Fix#95413
There's some subtle interaction between inferred expressions being
passed as an argument to fn calls with fewer than expected arguments. To
avoid the ICE, I'm changing indexing operations with `.get(idx)`, but
the underlying logic still needs to be audited as it was written with
the assumption that `final_arg_types` and `provided_args` have the right
length.
Address 96638.
Fix -Zdump-mir-dataflow by implementing DebugWithContext for ChunkedBitSet
`DebugWithContext` is used to format changes to dataflow state along with MIR
in graphviz dot files. In the case of `ChunkedBitSet` it was left unimplemented,
so attempts to use `-Zdump-mir-dataflow -Zdump-mir=all` resulted in an ICE:
> thread 'rustc' panicked at 'not implemented: implement when/if needed',
Provide the missing implementation.
r? `@nnethercote`
rustc: Panic by default in `DefIdTree::parent`
Only crate root def-ids don't have a parent, and in majority of cases the argument of `DefIdTree::parent` cannot be a crate root.
So we now panic by default in `parent` and introduce a new non-panicing function `opt_parent` for cases where the argument can be a crate root.
Same applies to `local_parent`/`opt_local_parent`.
Only crate root def-ids don't have a parent, and in majority of cases the argument of `DefIdTree::parent` cannot be a crate root.
So we now panic by default in `parent` and introduce a new non-panicing function `opt_parent` for cases where the argument can be a crate root.
Same applies to `local_parent`/`opt_local_parent`.
rustdoc: Resolve doc links referring to `macro_rules` items
cc https://github.com/rust-lang/rust/issues/81633
UPD: the fallback to considering *all* `macro_rules` in the crate for unresolved names is not removed in this PR, it will be removed separately and will be run through crater.
The reverse postorder, unlike preorder, is now cached inside the MIR
body. Code generation uses reverse postorder anyway, so it might be
a small perf improvement to use it here as well.
Also report the call site of PME errors locally.
Note this does not produce a full stack all the way to the first call that specifies all monomorphic parameters, it's just shallowly mentioning the last call site.
previous work: https://github.com/rust-lang/rust/pull/85633
tracking issue: https://github.com/rust-lang/rust/issues/85155
r? `@lqd`
I figured we could get some improvement for traces in local crates without going into the backtrace hell you landed in last time
`RValue::Discriminant` returns zero for types without discriminant.
This guarantee is already documented for `discriminant_value`
intrinsics which is implemented in terms of `RValue::Discriminant`.
Using an obviously-placeholder syntax. An RFC would still be needed before this could have any chance at stabilization, and it might be removed at any point.
But I'd really like to have it in nightly at least to ensure it works well with try_trait_v2, especially as we refactor the traits.
