By heap allocating the argument within `NtPath`, `NtVis`, and `NtStmt`.
This slightly reduces cumulative and peak allocation amounts, most
notably on `deep-vector`.
Currently it's called in `parse_tt` every time a match rule is invoked.
This commit moves it so it's called instead once per match rule, in
`compile_declarative_macro. This is a performance win.
The commit also moves `compute_locs` out of `TtParser`, because there's
no longer any reason for it to be in there.
Use the proc-macro descr to track their individual expansions with
self-profiling events. This will help diagnose performance issues
with slow proc-macros.
In #95555 this was moved out of `parse_tt_inner` and `nameize` into
`compute_locs`. But the next commit will be moving `compute_locs`
outwards to a place that isn't suitable for the missing fragment
identifier checking. So this reinstates the old checking.
Add an option for enabling and disabling Fluent's directionality
isolation markers in output. Disabled by default as these can render in
some terminals and applications.
Signed-off-by: David Wood <david.wood@huawei.com>
Extend loading of Fluent bundles so that bundles can be loaded from the
sysroot based on the language requested by the user, or using a nightly
flag.
Sysroot bundles are loaded from `$sysroot/share/locale/$locale/*.ftl`.
Signed-off-by: David Wood <david.wood@huawei.com>
This commit updates the signatures of all diagnostic functions to accept
types that can be converted into a `DiagnosticMessage`. This enables
existing diagnostic calls to continue to work as before and Fluent
identifiers to be provided. The `SessionDiagnostic` derive just
generates normal diagnostic calls, so these APIs had to be modified to
accept Fluent identifiers.
In addition, loading of the "fallback" Fluent bundle, which contains the
built-in English messages, has been implemented.
Each diagnostic now has "arguments" which correspond to variables in the
Fluent messages (necessary to render a Fluent message) but no API for
adding arguments has been added yet. Therefore, diagnostics (that do not
require interpolation) can be converted to use Fluent identifiers and
will be output as before.
`MultiSpan` contains labels, which are more complicated with the
introduction of diagnostic translation and will use types from
`rustc_errors` - however, `rustc_errors` depends on `rustc_span` so
`rustc_span` cannot use types like `DiagnosticMessage` without
dependency cycles. Introduce a new `rustc_error_messages` crate that can
contain `DiagnosticMessage` and `MultiSpan`.
Signed-off-by: David Wood <david.wood@huawei.com>
Introduce a `DiagnosticMessage` type that will enable diagnostic
messages to be simple strings or Fluent identifiers.
`DiagnosticMessage` is now used in the implementation of the standard
`DiagnosticBuilder` APIs.
Signed-off-by: David Wood <david.wood@huawei.com>
Reduce unnecessary escaping in proc_macro::Literal::character/string
I noticed that https://doc.rust-lang.org/proc_macro/struct.Literal.html#method.character is producing unreadable literals that make macro-expanded code unnecessarily hard to read. Since the proc macro server was using `escape_unicode()`, every char is escaped using `\u{…}` regardless of whether there is any need to do so. For example `Literal::character('=')` would previously produce `'\u{3d}'` which unnecessarily obscures the meaning when reading the macro-expanded code.
I've changed Literal::string also in this PR because `str`'s `Debug` impl is also smarter than just calling `escape_debug` on every char. For example `Literal::string("ferris's")` would previously produce `"ferris\'s"` but will now produce `"ferris's"`.
`parse_tt` currently traverses a `&[TokenTree]` to do matching. But this
is a bad representation for the traversal.
- `TokenTree` is nested, and there's a bunch of expensive and fiddly
state required to handle entering and exiting nested submatchers.
- There are three positions (sequence separators, sequence Kleene ops,
and end of the matcher) that are represented by an index that exceeds
the end of the `&[TokenTree]`, which is clumsy and error-prone.
This commit introduces a new representation called `MatcherLoc` that is
designed specifically for matching. It fixes all the above problems,
making the code much easier to read. A `&[TokenTree]` is converted to a
`&[MatcherLoc]` before matching begins. Despite the cost of the
conversion, it's still a net performance win, because various pieces of
traversal state are computed once up-front, rather than having to be
recomputed repeatedly during the macro matching.
Some improvements worth noting.
- `parse_tt_inner` is *much* easier to read. No more having to compare
`idx` against `len` and read comments to understand what the result
means.
- The handling of `Delimited` in `parse_tt_inner` is now trivial.
- The three end-of-sequence cases in `parse_tt_inner` are now handled in
three separate match arms, and the control flow is much simpler.
- `nameize` is no longer recursive.
- There were two places that issued "missing fragment specifier" errors:
one in `parse_tt_inner()`, and one in `nameize()`. Presumably the
latter was never executed. There's now a single place issuing these
errors, in `compute_locs()`.
- The number of heap allocations done for a `check full` build of
`async-std-1.10.0` (an extreme example of heavy macro use) drops from
11.8M to 2.6M, and most of these occur outside of macro matching.
- The size of `MatcherPos` drops from 64 bytes to 16 bytes. Small enough
that it no longer needs boxing, which partly accounts for the
reduction in allocations.
- The rest of the drop in allocations is due to the removal of
`MatcherKind`, because we no longer need to record anything for the
parent matcher when entering a submatcher.
- Overall it reduces code size by 45 lines.
It's only used in one place, and there we clone and then make a bunch of
modifications. It's clearer if we duplicate more explicitly, and there's
a symmetry now between `sequence()` and `empty_sequence()`.
`parse_tt` needs a way to get from within submatchers make to the
enclosing submatchers. Currently it has two distinct mechanisms for
this:
- `Delimited` submatchers use `MatcherPos::stack` to record stuff about
the parent (and further back ancestors).
- `Sequence` submatchers use `MatcherPosSequence::parent` to point to
the parent matcher position.
Having two mechanisms is really confusing, and it took me a long time to
understand all this.
This commit eliminates `MatcherPos::stack`, and changes `Delimited`
submatchers to use the same mechanism as sequence submatchers. That
mechanism is also changed a bit: instead of storing the entire parent
`MatcherPos`, we now only store the necessary parts from the parent
`MatcherPos`.
Overall this is a small performance win, with the positives outweighing
the negatives, but it's mostly for clarity.
Spellchecking compiler comments
This PR cleans up the rest of the spelling mistakes in the compiler comments. This PR does not change any literal or code spelling issues.
Currently, we detect an exit from a `Delimited` submatcher when `idx`
exceeds the bounds of the current submatcher *and* there is a `stack`
entry.
This commit changes it to something simpler: just look for a
`CloseDelim` token.
Yet more `parse_tt` improvements
Including lots of comment improvements, and an overhaul of how `matches` work that gives big speedups.
r? `@petrochenkov`
Currently, matches within a sequence are recorded in a new empty
`matches` vector. Then when the sequence finishes the matches are merged
into the `matches` vector of the parent.
This commit changes things so that a sequence mp inherits the matches
made so far. This means that additional matches from the sequence don't
need to be merged into the parent. `push_match` becomes more
complicated, and the current sequence depth needs to be tracked. But
it's a sizeable performance win because it avoids one or more
`push_match` calls on every iteration of a sequence.
The commit also removes `match_hi`, which is no longer necessary.
Ignore doc comments in a declarative macro matcher.
Fixes#95267. Reverts to the old behaviour before #95159 introduced a
regression.
r? `@petrochenkov`
Remove `Nonterminal::NtTT`.
It's only needed for macro expansion, not as a general element in the
AST. This commit removes it, adds `NtOrTt` for the parser and macro
expansion cases, and renames the variants in `NamedMatch` to better
match the new type.
r? `@petrochenkov`
It's only needed for macro expansion, not as a general element in the
AST. This commit removes it, adds `NtOrTt` for the parser and macro
expansion cases, and renames the variants in `NamedMatch` to better
match the new type.
Remove `Session::one_time_diagnostic`
This is untracked mutable state, which modified the behaviour of queries.
It was used for 2 things: some full-blown errors, but mostly for lint declaration notes ("the lint level is defined here" notes).
It is replaced by the diagnostic deduplication infra which already exists in the diagnostic emitter.
A new diagnostic level `OnceNote` is introduced specifically for lint notes, to deduplicate subdiagnostics.
As a drive-by, diagnostic emission takes a `&mut` to allow dropping the `SubDiagnostic`s.
Currently it copies a `KleeneOp` and a `Token` out of a
`SequenceRepetition`. It's better to store a reference to the
`SequenceRepetition`, which is now possible due to #95159 having changed
the lifetimes.
The `Lrc` is only relevant within `transcribe()`. There, the `Lrc` is
helpful for the non-`NtTT` cases, because the entire nonterminal is
cloned. But for the `NtTT` cases the inner token tree is cloned (a full
clone) and so the `Lrc` is of no help.
This commit splits the `NtTT` and non-`NtTT` cases, avoiding the useless
`Lrc` in the former case, for the following effect on macro-heavy
crates.
- It reduces the total number of allocations a lot.
- It increases the size of some of the remaining allocations.
- It doesn't affect *peak* memory usage, because the larger allocations
are short-lived.
This overall gives a speed win.
Introduce `TtParser`
These commits make a number of changes to declarative macro expansion, resulting in code that is shorter, simpler, and faster.
Best reviewed one commit at a time.
r? `@petrochenkov`
As its name suggests, `TokenTreeOrTokenTreeSlice` is either a single
`TokenTree` or a slice of them. It has methods `len` and `get_tt` that
let it be treated much like an ordinary slice. The reason it isn't an
ordinary slice is that for `TokenTree::Delimited` the open and close
delimiters are represented implicitly, and when they are needed they are
constructed on the fly with `Delimited::{open,close}_tt`, rather than
being present in memory.
This commit changes `Delimited` so the open and close delimiters are
represented explicitly. As a result, `TokenTreeOrTokenTreeSlice` is no
longer needed and `MatcherPos` and `MatcherTtFrame` can just use an
ordinary slice. `TokenTree::{len,get_tt}` are also removed, because they
were only needed to support `TokenTreeOrTokenTreeSlice`.
The change makes the code shorter and a little bit faster on benchmarks
that use macro expansion heavily, partly because `MatcherPos` is a lot
smaller (less data to `memcpy`) and partly because ordinary slice
operations are faster than `TokenTreeOrTokenTreeSlice::{len,get_tt}`.
By putting them in `TtParser`, we can reuse them for every rule in a
macro. With that done, they can be `SmallVec` instead of `Vec`, and this
is a performance win because these vectors are hot and `SmallVec`
operations are a bit slower due to always needing an "inline or heap?"
check.
This type was a small performance win for `html5ever`, which uses a
macro with hundreds of very simple rules that don't contain any
metavariables. But this type is complicated (extra lifetimes) and
perf-neutral for macros that do have metavariables.
This commit removes `MatcherPosHandle`, simplifying things a lot. This
increases the allocation rate for `html5ever` and similar cases a bit,
but makes things easier for follow-up changes that will improve
performance more than what we lost here.
It currently has no state, just the three methods `parse_tt`,
`parse_tt_inner`, and `bb_items_ambiguity_error`.
This commit is large but trivial, and mostly consists of changes to the
indentation of those methods. Subsequent commits will do more.
There are a few places were we have to construct it, though, and a few
places that are more invasive to change. To do this, we create a
constructor with a long obvious name.
More robust fallback for `use` suggestion
Our old way to suggest where to add `use`s would first look for pre-existing `use`s in the relevant crate/module, and if there are *no* uses, it would fallback on trying to use another item as the basis for the suggestion.
But this was fragile, as illustrated in issue #87613
This PR instead identifies span of the first token after any inner attributes, and uses *that* as the fallback for the `use` suggestion.
Fix#87613
The current structure makes it hard to tell that there are just four
distinct code paths, depending on how many items there are in `bb_items`
and `next_items`. This commit introduces a `match` that clarifies
things.
Ensure stability directives are checked in all cases
Split off #93017
Stability and deprecation were not checked in all cases, for instance if a type error happened.
This PR moves the check earlier in the pipeline to ensure the errors are emitted in all cases.
r? `@lcnr`
Fix invalid lint_node_id being put on a removed stmt
This pull-request remove a invalid `assign_id!` being put on an stmt node.
The problem is that this node is being removed away by a cfg making it unreachable when triggering a buffered lint.
The comment in the other match arm already tell to not assign a id because it could have a `#[cfg()]` so this is just respecting the comment.
Fixes https://github.com/rust-lang/rust/issues/94523
r? ```````@petrochenkov```````
There are three `Option` fields in `MatcherPos` that are only used in
tandem. This commit combines them, making the code slightly easier to
read. (It also makes clear that the `sep` field arguably should have
been `Option<Option<Token>>`!)
To avoid the strange style where comments force `else` onto its own
line.
The commit also removes several else-after-return constructs, which can
be hard to read.
Improve allowness of the unexpected_cfgs lint
This pull-request improve the allowness (`#[allow(...)]`) of the `unexpected_cfgs` lint.
Before this PR only crate level `#![allow(unexpected_cfgs)]` worked, now with this PR it also work when put around `cfg!` or if it is in a upper level. Making it work ~for the attributes `cfg`, `cfg_attr`, ...~ for the same level is awkward as the current code is design to give "Some parent node that is close to this macro call" (cf. https://doc.rust-lang.org/nightly/nightly-rustc/rustc_expand/base/struct.ExpansionData.html) meaning that allow on the same line as an attribute won't work. I'm note even sure if this would be possible.
Found while working on https://github.com/rust-lang/rust/pull/94298.
r? ````````@petrochenkov````````
* Recover from invalid `'label: ` before block.
* Make suggestion to enclose statements in a block multipart.
* Point at `match`, `while`, `loop` and `unsafe` keywords when failing
to parse their expression.
* Do not suggest `{ ; }`.
* Do not suggest `|` when very unlikely to be what was wanted (in `let`
statements).
As an example:
#[test]
#[ignore = "not yet implemented"]
fn test_ignored() {
...
}
Will now render as:
running 2 tests
test tests::test_ignored ... ignored, not yet implemented
test result: ok. 1 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out; finished in 0.00s
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 is the biggest of these PRs and handles the changes outside of rustdoc, rustc_typeck, rustc_const_eval, rustc_trait_selection, which were handled in PRs #94139, #94142, #94143, #94144.
expand: Pick `cfg`s and `cfg_attrs` one by one, like other attributes
This is a rebase of https://github.com/rust-lang/rust/pull/83354, but without any language-changing parts ~(except for https://github.com/rust-lang/rust/pull/84110)~, i.e. the attribute expansion order is the same.
This is a pre-requisite for any other changes making cfg attributes closer to regular macro attributes
- Possibly changing their expansion order (https://github.com/rust-lang/rust/issues/83331)
- Keeping macro backtraces for cfg attributes, or otherwise making them visible after expansion without keeping them in place literally (https://github.com/rust-lang/rust/pull/84110).
Two exceptions to the "one by one" behavior are:
- cfgs eagerly expanded by `derive` and `cfg_eval`, they are still expanded in a batch, that's by design.
- cfgs at the crate root, they are currently expanded not during the main expansion pass, but before that, during `#![feature]` collection. I'll try to disentangle that logic later in a separate PR.
r? `@Aaron1011`
Replace usages of vec![].into_iter with [].into_iter
`[].into_iter` is idiomatic over `vec![].into_iter` because its simpler and faster (unless the vec is optimized away in which case it would be the same)
So we should change all the implementation, documentation and tests to use it.
I skipped:
* `src/tools` - Those are copied in from upstream
* `src/test/ui` - Hard to tell if `vec![].into_iter` was used intentionally or not here and not much benefit to changing it.
* any case where `vec![].into_iter` was used because we specifically needed a `Vec::IntoIter<T>`
* any case where it looked like we were intentionally using `vec![].into_iter` to test it.
ast: Avoid aborts on fatal errors thrown from mutable AST visitor
Set the node to some dummy value and rethrow the error instead.
When using the old aborting `visit_clobber` in `InvocationCollector::visit_crate` the next tests abort due to fatal errors:
```
ui\modules\path-invalid-form.rs
ui\modules\path-macro.rs
ui\modules\path-no-file-name.rs
ui\parser\issues\issue-5806.rs
ui\parser\mod_file_with_path_attr.rs
```
Follow up to https://github.com/rust-lang/rust/pull/91313.
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`
By changing `as_str()` to take `&self` instead of `self`, we can just
return `&str`. We're still lying about lifetimes, but it's a smaller lie
than before, where `SymbolStr` contained a (fake) `&'static str`!
This feature is aimed at giving proc macros access to powers similar to
those used by builtin macros such as `format_args!` or `concat!`. These
macros are able to accept macros in place of string literal parameters,
such as the format string, as they perform recursive macro expansion
while being expanded.
This can be especially useful in many cases thanks to helper macros like
`concat!`, `stringify!` and `include_str!` which are often used to
construct string literals at compile-time in user code.
For now, this method only allows expanding macros which produce
literals, although more expresisons will be supported before the method
is stabilized.
The only reason to use `abort_if_errors` is when the program is so broken that either:
1. later passes get confused and ICE
2. any diagnostics from later passes would be noise
This is never the case for lints, because the compiler has to be able to deal with `allow`-ed lints.
So it can continue to lint and compile even if there are lint errors.
rustc_ast: Turn `MutVisitor::token_visiting_enabled` into a constant
It's a visitor property rather than something that needs to be determined at runtime
Adopt let_else across the compiler
This performs a substitution of code following the pattern:
```
let <id> = if let <pat> = ... { identity } else { ... : ! };
```
To simplify it to:
```
let <pat> = ... { identity } else { ... : ! };
```
By adopting the `let_else` feature (cc #87335).
The PR also updates the syn crate because the currently used version of the crate doesn't support `let_else` syntax yet.
Note: Generally I'm the person who *removes* usages of unstable features from the compiler, not adds more usages of them, but in this instance I think it hopefully helps the feature get stabilized sooner and in a better state. I have written a [comment](https://github.com/rust-lang/rust/issues/87335#issuecomment-944846205) on the tracking issue about my experience and what I feel could be improved before stabilization of `let_else`.
This performs a substitution of code following the pattern:
let <id> = if let <pat> = ... { identity } else { ... : ! };
To simplify it to:
let <pat> = ... { identity } else { ... : ! };
By adopting the let_else feature.
Fix linting when trailing macro expands to a trailing semi
When a macro is used in the trailing expression position of a block
(e.g. `fn foo() { my_macro!() }`), we currently parse it as an
expression, rather than a statement. As a result, we ended up
using the `NodeId` of the containing statement as our `lint_node_id`,
even though we don't normally do this for macro calls.
If such a macro expands to an expression with a `#[cfg]` attribute,
then the trailing statement can get removed entirely. This lead to
an ICE, since we were usng the `NodeId` of the expression to emit
a lint.
Ths commit makes us skip updating `lint_node_id` when handling
a macro in trailing expression position. This will cause us to
lint at the closest parent of the macro call.
When a macro is used in the trailing expression position of a block
(e.g. `fn foo() { my_macro!() }`), we currently parse it as an
expression, rather than a statement. As a result, we ended up
using the `NodeId` of the containing statement as our `lint_node_id`,
even though we don't normally do this for macro calls.
If such a macro expands to an expression with a `#[cfg]` attribute,
then the trailing statement can get removed entirely. This lead to
an ICE, since we were usng the `NodeId` of the expression to emit
a lint.
Ths commit makes us skip updating `lint_node_id` when handling
a macro in trailing expression position. This will cause us to
lint at the closest parent of the macro call.
Encode spans relative to the enclosing item
The aim of this PR is to avoid recomputing queries when code is moved without modification.
MCP at https://github.com/rust-lang/compiler-team/issues/443
This is achieved by :
1. storing the HIR owner LocalDefId information inside the span;
2. encoding and decoding spans relative to the enclosing item in the incremental on-disk cache;
3. marking a dependency to the `source_span(LocalDefId)` query when we translate a span from the short (`Span`) representation to its explicit (`SpanData`) representation.
Since all client code uses `Span`, step 3 ensures that all manipulations
of span byte positions actually create the dependency edge between
the caller and the `source_span(LocalDefId)`.
This query return the actual absolute span of the parent item.
As a consequence, any source code motion that changes the absolute byte position of a node will either:
- modify the distance to the parent's beginning, so change the relative span's hash;
- dirty `source_span`, and trigger the incremental recomputation of all code that
depends on the span's absolute byte position.
With this scheme, I believe the dependency tracking to be accurate.
For the moment, the spans are marked during lowering.
I'd rather do this during def-collection,
but the AST MutVisitor is not practical enough just yet.
The only difference is that we attach macro-expanded spans
to their expansion point instead of the macro itself.
Add proc_macro::Span::{before, after}.
This adds `proc_macro::Span::before()` and `proc_macro::Span::after()` to get a zero width span at the start or end of the span.
These are equivalent to rustc's `Span::shrink_to_lo()` and `Span::shrink_to_hi()` but with a less cryptic name. They are useful when generating diagnostlics like "missing \<thing\> after \<thing\>".
E.g.
```rust
syn::Error::new(ident.span().after(), "missing `:` after field name").into_compile_error()
```
Detect bare blocks with type ascription that were meant to be a `struct` literal
Address part of #34255.
Potential improvement: silence the other knock down errors in `issue-34255-1.rs`.
expand: Treat more macro calls as statement macro calls
This PR implements the suggestion from https://github.com/rust-lang/rust/pull/87981#issuecomment-906641052 and treats fn-like macro calls inside `StmtKind::Item` and `StmtKind::Semi` as statement macro calls, which is consistent with treatment of attribute invocations in the same positions and with token-based macro expansion model in general.
This also allows to remove a special case in `NodeId` assignment (previously tried in #87779), and to use statement `NodeId`s for linting (`assign_id!`).
r? `@Aaron1011`
Path remapping: Make behavior of diagnostics output dependent on presence of --remap-path-prefix.
This PR fixes a regression (#87745) with `--remap-path-prefix` where the flag stopped causing diagnostic messages to be remapped as well. The regression was introduced in https://github.com/rust-lang/rust/pull/83813 where we erroneously assumed that remapping of diagnostic messages was not desired anymore (because #70642 partially undid that functionality with nobody objecting).
The issue is fixed by making `--remap-path-prefix` remap diagnostic messages again, including for paths that have been remapped in upstream crates (e.g. the standard library). This means that "sysroot-localization" (implemented in #70642) is also disabled if `rustc` is invoked with `--remap-path-prefix`. The assumption is that once someone starts explicitly remapping paths they also don't want paths to their local Rust installation in their build output.
In the future we might want to give more fine-grained control over this behavior via compiler flags (see https://github.com/rust-lang/rfcs/pull/3127 for a related RFC). For now this PR is intended as a regression fix.
This PR is an alternative to https://github.com/rust-lang/rust/pull/88191, which makes diagnostic messages be remapped unconditionally. That approach, however, would effectively revert #70642.
Fixes https://github.com/rust-lang/rust/issues/87745.
cc `@cbeuw`
r? `@ghost`
Instead of updating global state to mark attributes as used,
we now explicitly emit a warning when an attribute is used in
an unsupported position. As a side effect, we are to emit more
detailed warning messages (instead of just a generic "unused" message).
`Session.check_name` is removed, since its only purpose was to mark
the attribute as used. All of the callers are modified to use
`Attribute.has_name`
Additionally, `AttributeType::AssumedUsed` is removed - an 'assumed
used' attribute is implemented by simply not performing any checks
in `CheckAttrVisitor` for a particular attribute.
We no longer emit unused attribute warnings for the `#[rustc_dummy]`
attribute - it's an internal attribute used for tests, so it doesn't
mark sense to treat it as 'unused'.
With this commit, a large source of global untracked state is removed.
Fixes#87877
This change interacts badly with `noop_flat_map_stmt`,
which synthesizes multiple statements with the same `NodeId`.
I'm working on a better fix that will still allow us to
remove this special case. For now, let's revert the change
to fix the ICE.
This reverts commit a4262cc984, reversing
changes made to 8ee962f88e.
Support negative numbers in Literal::from_str
proc_macro::Literal has allowed negative numbers in a single literal token ever since Rust 1.29, using https://doc.rust-lang.org/stable/proc_macro/struct.Literal.html#method.isize_unsuffixed and similar constructors.
```rust
let lit = proc_macro::Literal::isize_unsuffixed(-10);
```
However, the suite of constructors on Literal is not sufficient for all use cases, for example arbitrary precision floats, or custom suffixes in FFI macros.
```rust
let lit = proc_macro::Literal::f64_unsuffixed(0.101001000100001000001000000100000001); // :(
let lit = proc_macro::Literal::i???_suffixed(10ulong); // :(
```
For those, macros construct the literal using from_str instead, which preserves arbitrary precision, custom suffixes, base, and digit grouping.
```rust
let lit = "0.101001000100001000001000000100000001".parse::<Literal>().unwrap();
let lit = "10ulong".parse::<Literal>().unwrap();
let lit = "0b1000_0100_0010_0001".parse::<Literal>().unwrap();
```
However, until this PR it was not possible to construct a literal token that is **both** negative **and** preserving of arbitrary precision etc.
This PR fixes `Literal::from_str` to recognize negative integer and float literals.
rfc3052 followup: Remove authors field from Cargo manifests
Since RFC 3052 soft deprecated the authors field, hiding it from
crates.io, docs.rs, and making Cargo not add it by default, and it is
not generally up to date/useful information for contributors, we may as well
remove it from crates in this repo.
Since RFC 3052 soft deprecated the authors field anyway, hiding it from
crates.io, docs.rs, and making Cargo not add it by default, and it is
not generally up to date/useful information, we should remove it from
crates in this repo.
Display an extra note for trailing semicolon lint with trailing macro
Currently, we parse macros at the end of a block
(e.g. `fn foo() { my_macro!() }`) as expressions, rather than
statements. This means that a macro invoked in this position
cannot expand to items or semicolon-terminated expressions.
In the future, we might want to start parsing these kinds of macros
as statements. This would make expansion more 'token-based'
(i.e. macro expansion behaves (almost) as if you just textually
replaced the macro invocation with its output). However,
this is a breaking change (see PR #78991), so it will require
further discussion.
Since the current behavior will not be changing any time soon,
we need to address the interaction with the
`SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` lint. Since we are parsing
the result of macro expansion as an expression, we will emit a lint
if there's a trailing semicolon in the macro output. However, this
results in a somewhat confusing message for users, since it visually
looks like there should be no problem with having a semicolon
at the end of a block
(e.g. `fn foo() { my_macro!() }` => `fn foo() { produced_expr; }`)
To help reduce confusion, this commit adds a note explaining
that the macro is being interpreted as an expression. Additionally,
we suggest adding a semicolon after the macro *invocation* - this
will cause us to parse the macro call as a statement. We do *not*
use a structured suggestion for this, since the user may actually
want to remove the semicolon from the macro definition (allowing
the block to evaluate to the expression produced by the macro).
Currently, we parse macros at the end of a block
(e.g. `fn foo() { my_macro!() }`) as expressions, rather than
statements. This means that a macro invoked in this position
cannot expand to items or semicolon-terminated expressions.
In the future, we might want to start parsing these kinds of macros
as statements. This would make expansion more 'token-based'
(i.e. macro expansion behaves (almost) as if you just textually
replaced the macro invocation with its output). However,
this is a breaking change (see PR #78991), so it will require
further discussion.
Since the current behavior will not be changing any time soon,
we need to address the interaction with the
`SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` lint. Since we are parsing
the result of macro expansion as an expression, we will emit a lint
if there's a trailing semicolon in the macro output. However, this
results in a somewhat confusing message for users, since it visually
looks like there should be no problem with having a semicolon
at the end of a block
(e.g. `fn foo() { my_macro!() }` => `fn foo() { produced_expr; }`)
To help reduce confusion, this commit adds a note explaining
that the macro is being interpreted as an expression. Additionally,
we suggest adding a semicolon after the macro *invocation* - this
will cause us to parse the macro call as a statement. We do *not*
use a structured suggestion for this, since the user may actually
want to remove the semicolon from the macro definition (allowing
the block to evaluate to the expression produced by the macro).
These attributes are currently discarded.
This may change in the future (see #63221), but for now,
placing inert attributes on a macro invocation does nothing,
so we should warn users about it.
Technically, it's possible for there to be attribute macro
on the same macro invocation (or at a higher scope), which
inspects the inert attribute. For example:
```rust
#[look_for_inline_attr]
#[inline]
my_macro!()
#[look_for_nested_inline]
mod foo { #[inline] my_macro!() }
```
However, this would be a very strange thing to do.
Anyone running into this can manually suppress the warning.
