A recent PR increased the size, which caused regressions. This uses the
existing generic infrastructure to differentiate between the hot path
and the diagnostics path.
Encode spans relative to the enclosing item -- enable on nightly
Follow-up to #84373 with the flag `-Zincremental-relative-spans` set by default.
This PR seeks to remove one of the main shortcomings of incremental: the handling of spans.
Changing the contents of a function may require redoing part of the compilation process for another function in another file because of span information is changed.
Within one file: all the spans in HIR change, so typechecking had to be re-done.
Between files: spans of associated types/consts/functions change, so type-based resolution needs to be re-done (hygiene information is stored in the span).
The flag `-Zincremental-relative-spans` encodes local spans relative to the span of an item, stored inside the `source_span` query.
Trap: stashed diagnostics are referenced by the "raw" span, so stealing them requires to remove the span's parent.
In order to avoid too much traffic in the span interner, span encoding uses the `ctxt_or_tag` field to encode:
- the parent when the `SyntaxContext` is 0;
- the `SyntaxContext` when the parent is `None`.
Even with this, the PR creates a lot of traffic to the Span interner, when a Span has both a LocalDefId parent and a non-root SyntaxContext. They appear in lowering, when we add a parent to all spans, including those which come from macros, and during inlining when we mark inlined spans.
The last commit changes how queries of `LocalDefId` manage their cache. I can put this in a separate PR if required.
Possible future directions:
- validate that all spans are marked in HIR validation;
- mark macro-expanded spans relative to the def-site and not the use-site.
Properly calculate best failure in macro matching
Previously, we used spans. This was not good. Sometimes, the span of the token that failed to match may come from a position later in the file which has been transcribed into a token stream way earlier in the file. If precisely this token fails to match, we think that it was the best match because its span is so high, even though other arms might have gotten further in the token stream.
We now try to properly use the location in the token stream.
This needs a little cleanup as the `best_failure` field is getting out of hand but it should be mostly good to go. I hope I didn't violate too many abstraction boundaries..
Previously, we used spans. This was not good. Sometimes, the span of the
token that failed to match may come from a position later in the file
which has been transcribed into a token stream way earlier in the file.
If precisely this token fails to match, we think that it was the best
match because its span is so high, even though other arms might have
gotten further in the token stream.
We now try to properly use the location in the token stream.
Remove `token::Lit` from `ast::MetaItemLit`.
Currently `ast::MetaItemLit` represents the literal kind twice. This PR removes that redundancy. Best reviewed one commit at a time.
r? `@petrochenkov`
compiler: remove unnecessary imports and qualified paths
Some of these imports were necessary before Edition 2021, others were already in the prelude.
I hope it's fine that this PR is so spread-out across files :/
This migrates everything but the `mbe` and `proc_macro` modules. It also
contains a few cleanups and drive-by/accidental diagnostic improvements
which can be seen in the diff for the UI tests.
This is required to distinguish between cooked and raw byte string
literals in an `ast::LitKind`, without referring to an adjacent
`token::Lit`. It's a prerequisite for the next commit.
There is code for converting `Attribute` (syntactic) to `MetaItem`
(semantic). There is also code for the reverse direction. The reverse
direction isn't really necessary; it's currently only used when
generating attributes, e.g. in `derive` code.
This commit adds some new functions for creating `Attributes`s directly,
without involving `MetaItem`s: `mk_attr_word`, `mk_attr_name_value_str`,
`mk_attr_nested_word`, and
`ExtCtxt::attr_{word,name_value_str,nested_word}`.
These new methods replace the old functions for creating `Attribute`s:
`mk_attr_inner`, `mk_attr_outer`, and `ExtCtxt::attribute`. Those
functions took `MetaItem`s as input, and relied on many other functions
that created `MetaItems`, which are also removed: `mk_name_value_item`,
`mk_list_item`, `mk_word_item`, `mk_nested_word_item`,
`{MetaItem,MetaItemKind,NestedMetaItem}::token_trees`,
`MetaItemKind::attr_args`, `MetaItemLit::{from_lit_kind,to_token}`,
`ExtCtxt::meta_word`.
Overall this cuts more than 100 lines of code and makes thing simpler.
`check_builtin_attribute` calls `parse_meta` to convert an `Attribute`
to a `MetaItem`, which it then checks. However, many callers of
`check_builtin_attribute` start with a `MetaItem`, and then convert it
to an `Attribute` by calling `cx.attribute(meta_item)`. This `MetaItem`
to `Attribute` to `MetaItem` conversion is silly.
This commit adds a new function `check_builtin_meta_item`, which can be
called instead from these call sites. `check_builtin_attribute` also now
calls it. The commit also renames `check_meta` as `check_attr` to better
match its arguments.
Change multiline span ASCII art visual order
Tweak the ASCII art for nested multiline spans so that we minimize line overlaps.
Partially addresses https://github.com/rust-lang/rust/issues/61017.
`Lit::from_included_bytes` calls `Lit::from_lit_kind`, but the two call
sites only need the resulting `token::Lit`, not the full `ast::Lit`.
This commit changes those call sites to use `LitKind::to_token_lit`,
which means `from_included_bytes` can be removed.
Split `MacArgs` in two.
`MacArgs` is an enum with three variants: `Empty`, `Delimited`, and `Eq`. It's used in two ways:
- For representing attribute macro arguments (e.g. in `AttrItem`), where all three variants are used.
- For representing function-like macros (e.g. in `MacCall` and `MacroDef`), where only the `Delimited` variant is used.
In other words, `MacArgs` is used in two quite different places due to them having partial overlap. I find this makes the code hard to read. It also leads to various unreachable code paths, and allows invalid values (such as accidentally using `MacArgs::Empty` in a `MacCall`).
This commit splits `MacArgs` in two:
- `DelimArgs` is a new struct just for the "delimited arguments" case. It is now used in `MacCall` and `MacroDef`.
- `AttrArgs` is a renaming of the old `MacArgs` enum for the attribute macro case. Its `Delimited` variant now contains a `DelimArgs`.
Various other related things are renamed as well.
These changes make the code clearer, avoids several unreachable paths, and disallows the invalid values.
r? `@petrochenkov`
`MacArgs` is an enum with three variants: `Empty`, `Delimited`, and `Eq`. It's
used in two ways:
- For representing attribute macro arguments (e.g. in `AttrItem`), where all
three variants are used.
- For representing function-like macros (e.g. in `MacCall` and `MacroDef`),
where only the `Delimited` variant is used.
In other words, `MacArgs` is used in two quite different places due to them
having partial overlap. I find this makes the code hard to read. It also leads
to various unreachable code paths, and allows invalid values (such as
accidentally using `MacArgs::Empty` in a `MacCall`).
This commit splits `MacArgs` in two:
- `DelimArgs` is a new struct just for the "delimited arguments" case. It is
now used in `MacCall` and `MacroDef`.
- `AttrArgs` is a renaming of the old `MacArgs` enum for the attribute macro
case. Its `Delimited` variant now contains a `DelimArgs`.
Various other related things are renamed as well.
These changes make the code clearer, avoids several unreachable paths, and
disallows the invalid values.
Use `token::Lit` in `ast::ExprKind::Lit`.
Instead of `ast::Lit`.
Literal lowering now happens at two different times. Expression literals are lowered when HIR is crated. Attribute literals are lowered during parsing.
r? `@petrochenkov`
