rustdoc: Censor certain complex unevaluated const exprs
Fixes#97933.
This is more of a hotfix for the aforementioned issue. By that, I mean that my proposed patch is
not the best solution but one that does not change as much existing code.
It treats symptoms rather than the root cause.
This PR “censors” certain complex unevaluated constant expressions like `match`es, blocks, function calls, struct literals etc. by pretty-printing them as `_` / `{ _ }` (number and string literals, paths and `()` are still printed as one would expect).
Resorting to this placeholder is preferable to printing the full expression verbatim since
they can be quite large and verbose resulting in an unreadable mess in the generated documentation.
Further, mindlessly printing the const would leak private and `doc(hidden)` struct fields (#97933), at least in the current
stable & nightly implementations which rely on `span_to_snippet` (!) and `rustc_hir_pretty::id_to_string`.
The censoring of _verbose_ expressions is probably going to stay longer term.
However, in regards to private and `doc(hidden)` struct fields, I have a more proper fix in mind
which I have already partially implemented locally and for which I am going to open a separate PR sometime soon.
For that, I was already in contact with `@GuillaumeGomez.`
The proper fix involves rustdoc not falling back on pretty-printing unevaluated consts so easily (what this PR is concerned about)
and instead preferring to print evaluated consts which contain more information allowing it to selectively hide private and `doc(hidden)` fields, create hyperlinks etc. generally making the output more granular and precise (compared to the brutal `_` placeholder).
Unfortunately, I was a bit too late and the issue just hit stable (1.62).
Should this be backported to beta or even a potential 1.62.1?
r? `@GuillaumeGomez`
And likewise for the `Const::val` method.
Because its type is called `ConstKind`. Also `val` is a confusing name
because `ConstKind` is an enum with seven variants, one of which is
called `Value`. Also, this gives consistency with `TyS` and `PredicateS`
which have `kind` fields.
The commit also renames a few `Const` variables from `val` to `c`, to
avoid confusion with the `ConstKind::Value` variant.
Lifetime variance fixes for rustdoc
#97287 migrates rustc to a `Ty` type that is invariant over its lifetime `'tcx`, so I need to fix a bunch of places that assume that `Ty<'a>` and `Ty<'b>` can be unified by shortening both to some common lifetime.
This is doable, since everything is already `'tcx`, so all this PR does is be a bit more explicit that elided lifetimes are actually `'tcx`.
Split out from #97287 so the rustdoc team can review independently.
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`.
Remember mutability in `DefKind::Static`.
This allows to compute the `BodyOwnerKind` from `DefKind` only, and
removes a direct dependency of some MIR queries onto HIR.
As a side effect, it also simplifies metadata, since we don't need 4
flavours of `EntryKind::*Static` any more.
This allows to compute the `BodyOwnerKind` from `DefKind` only, and
removes a direct dependency of some MIR queries onto HIR.
As a side effect, it also simplifies metadata, since we don't need 4
flavours of `EntryKind::*Static` any more.
librustdoc: adopt let else in more places
Continuation of #89933, #91018, #91481, #93046, #93590, #94011.
I have extended my clippy lint to also recognize tuple passing and match statements. The diff caused by fixing it is way above 1 thousand lines. Thus, I split it up into multiple pull requests to make reviewing easier. This PR handles librustdoc.
Specifically, rename the `Const` struct as `ConstS` and re-introduce `Const` as
this:
```
pub struct Const<'tcx>(&'tcx Interned<ConstS>);
```
This now matches `Ty` and `Predicate` more closely, including using
pointer-based `eq` and `hash`.
Notable changes:
- `mk_const` now takes a `ConstS`.
- `Const` was copy, despite being 48 bytes. Now `ConstS` is not, so need a
we need separate arena for it, because we can't use the `Dropless` one any
more.
- Many `&'tcx Const<'tcx>`/`&Const<'tcx>` to `Const<'tcx>` changes
- Many `ct.ty` to `ct.ty()` and `ct.val` to `ct.val()` changes.
- Lots of tedious sigil fiddling.
Specifically, change `Region` from this:
```
pub type Region<'tcx> = &'tcx RegionKind;
```
to this:
```
pub struct Region<'tcx>(&'tcx Interned<RegionKind>);
```
This now matches `Ty` and `Predicate` more closely.
Things to note
- Regions have always been interned, but we haven't been using pointer-based
`Eq` and `Hash`. This is now happening.
- I chose to impl `Deref` for `Region` because it makes pattern matching a lot
nicer, and `Region` can be viewed as just a smart wrapper for `RegionKind`.
- Various methods are moved from `RegionKind` to `Region`.
- There is a lot of tedious sigil changes.
- A couple of types like `HighlightBuilder`, `RegionHighlightMode` now have a
`'tcx` lifetime because they hold a `Ty<'tcx>`, so they can call `mk_region`.
- A couple of test outputs change slightly, I'm not sure why, but the new
outputs are a little better.
rustdoc: Preserve rendering of macro_rules matchers when possible
Fixes#92331. This approach restores the behavior prior to #86282 **if** the matcher token held by the compiler **and** the matcher token found in the source code are identical TokenTrees. Thus #86208 remains fixed, but without regressing formatting for the vast majority of macros which are not macro-generated.
Rustdoc: use ThinVec for GenericArgs bindings
The bindings are almost always empty. This reduces the size of `PathSegment` and `GenericArgs` by about one fourth.
Remove `SymbolStr`
This was originally proposed in https://github.com/rust-lang/rust/pull/74554#discussion_r466203544. As well as removing the icky `SymbolStr` type, it allows the removal of a lot of `&` and `*` occurrences.
Best reviewed one commit at a time.
r? `@oli-obk`
`render/context` always runs after `run_global_context`, so it was always set to `true`.
This is a holdover from when rustdoc allowed configuring passes, but the `collapse-docs` pass was
removed ages ago, and the ability to configure passes is about to be removed.
