Improve suggestion for missing fmt str in println
Avoid using `concat!(fmt, "\n")` to improve the diagnostics being
emitted when the first `println!()` argument isn't a formatting string
literal.
Fix#52347.
This commit fixes an issue where multiple custom attributes could not be fed
into a custom derive in some situations with the `use_extern_macros` feature
enabled. The problem was that the macro expander didn't consider that it was
making progress when we were deducing that attributes should be lumped in with
custom derive invocations.
The fix applied here was to track in the expander if our attribute is changing
(getting stashed away elsewhere and replaced with a new invocation). If it is
swapped then it's considered progress, otherwise behavior should remain the
same.
Closes#52525
This commit stabilizes some of the `proc_macro` language feature as well as a
number of APIs in the `proc_macro` crate as [previously discussed][1]. This
means that on stable Rust you can now define custom procedural macros which
operate as attributes attached to items or `macro_rules!`-like bang-style
invocations. This extends the suite of currently stable procedural macros,
custom derives, with custom attributes and custom bang macros.
Note though that despite the stabilization in this commit procedural macros are
still not usable on stable Rust. To stabilize that we'll need to stabilize at
least part of the `use_extern_macros` feature. Currently you can define a
procedural macro attribute but you can't import it to call it!
A summary of the changes made in this PR (as well as the various consequences)
is:
* The `proc_macro` language and library features are now stable.
* Other APIs not stabilized in the `proc_macro` crate are now named under a
different feature, such as `proc_macro_diagnostic` or `proc_macro_span`.
* A few checks in resolution for `proc_macro` being enabled have switched over
to `use_extern_macros` being enabled. This means that code using
`#![feature(proc_macro)]` today will likely need to move to
`#![feature(use_extern_macros)]`.
It's intended that this PR, once landed, will be followed up with an attempt to
stabilize a small slice of `use_extern_macros` just for procedural macros to
make this feature 100% usable on stable.
[1]: https://internals.rust-lang.org/t/help-stabilize-a-subset-of-macros-2-0/7252
Make FileMap::{lines, multibyte_chars, non_narrow_chars} non-mutable.
This PR removes most of the interior mutability from `FileMap`, which should be beneficial, especially in a multithreaded setting. This is achieved by initializing the state in question when the filemap is constructed instead of during lexing. Hopefully this doesn't degrade performance.
cc @wesleywiser
add suggestion applicabilities to librustc and libsyntax
A down payment on #50723. Interested in feedback on whether my `MaybeIncorrect` vs. `MachineApplicable` judgement calls are well-calibrated (and that we have a consensus on what this means).
r? @Manishearth
cc @killercup @estebank
Consider this a down payment on #50723. To recap, an `Applicability`
enum was recently (#50204) added, to convey to Rustfix and other tools
whether we think it's OK for them to blindly apply the suggestion, or
whether to prompt a human for guidance (because the suggestion might
contain placeholders that we can't infer, or because we think it has a
sufficiently high probability of being wrong even though it's—
presumably—right often enough to be worth emitting in the first place).
When a suggestion is marked as `MaybeIncorrect`, we try to use comments
to indicate precisely why (although there are a few places where we just
say `// speculative` because the present author's subjective judgement
balked at the idea that the suggestion has no false positives).
The `run-rustfix` directive is opporunistically set on some relevant UI
tests (and a couple tests that were in the `test/ui/suggestions`
directory, even if the suggestions didn't originate in librustc or
libsyntax). This is less trivial than it sounds, because a surprising
number of test files aren't equipped to be tested as fixed even when
they contain successfully fixable errors, because, e.g., there are more,
not-directly-related errors after fixing. Some test files need an
attribute or underscore to avoid unused warnings tripping up the "fixed
code is still producing diagnostics" check despite the fixes being
correct; this is an interesting contrast-to/inconsistency-with the
behavior of UI tests (which secretly pass `-A unused`), a behavior which
we probably ought to resolve one way or the other (filed issue #50926).
A few suggestion labels are reworded (e.g., to avoid phrasing it as a
question, which which is discouraged by the style guidelines listed in
`.span_suggestion`'s doc-comment).
rustc: Disallow modules and macros in expansions
This commit feature gates generating modules and macro definitions in procedural
macro expansions. Custom derive is exempt from this check as it would be a large
retroactive breaking change (#50587). It's hoped that we can hopefully stem the
bleeding to figure out a better solution here before opening up the floodgates.
The restriction here is specifically targeted at surprising hygiene results [1]
that result in non-"copy/paste" behavior. Hygiene and procedural macros is
intended to be avoided as much as possible for Macros 1.2 by saying everything
is "as if you copy/pasted the code", but modules and macros are sort of weird
exceptions to this rule that aren't fully fleshed out.
[1]: https://github.com/rust-lang/rust/issues/50504#issuecomment-387734625
cc #50504
This commit feature gates generating modules and macro definitions in procedural
macro expansions. Custom derive is exempt from this check as it would be a large
retroactive breaking change (#50587). It's hoped that we can hopefully stem the
bleeding to figure out a better solution here before opening up the floodgates.
The restriction here is specifically targeted at surprising hygiene results [1]
that result in non-"copy/paste" behavior. Hygiene and procedural macros is
intended to be avoided as much as possible for Macros 1.2 by saying everything
is "as if you copy/pasted the code", but modules and macros are sort of weird
exceptions to this rule that aren't fully fleshed out.
[1]: https://github.com/rust-lang/rust/issues/50504#issuecomment-387734625
cc #50504
Warn on pointless #[derive] in more places
This fixes the regression in #49934 and ensures that unused `#[derive]` invocations on statements, expressions and generic type parameters survive to trip the `unused_attributes` lint. There is a separate warning hardcoded for `#[derive]` on macro invocations since linting (even the early-lint pass) occurs after expansion. This also adds regression tests for some nodes that were already warning properly.
closes#49934
This fixes the regression in #49934 and ensures that unused `#[derive]`s on statements, expressions and generic type parameters survive to trip the `unused_attributes` lint. For `#[derive]` on macro invocations it has a hardcoded warning since linting occurs after expansion. This also adds regression testing for some nodes that were already warning properly.
closes#49934
This commit starts to lay some groundwork for the stabilization of custom
attribute invocations and general procedural macros. It applies a number of
changes discussed on [internals] as well as a [recent issue][issue], namely:
* The path used to specify a custom attribute must be of length one and cannot
be a global path. This'll help future-proof us against any ambiguities and
give us more time to settle the precise syntax. In the meantime though a bare
identifier can be used and imported to invoke a custom attribute macro. A new
feature gate, `proc_macro_path_invoc`, was added to gate multi-segment paths
and absolute paths.
* The set of items which can be annotated by a custom procedural attribute has
been restricted. Statements, expressions, and modules are disallowed behind
two new feature gates: `proc_macro_expr` and `proc_macro_mod`.
* The input to procedural macro attributes has been restricted and adjusted.
Today an invocation like `#[foo(bar)]` will receive `(bar)` as the input token
stream, but after this PR it will only receive `bar` (the delimiters were
removed). Invocations like `#[foo]` are still allowed and will be invoked in
the same way as `#[foo()]`. This is a **breaking change** for all nightly
users as the syntax coming in to procedural macros will be tweaked slightly.
* Procedural macros (`foo!()` style) can only be expanded to item-like items by
default. A separate feature gate, `proc_macro_non_items`, is required to
expand to items like expressions, statements, etc.
Closes#50038
[internals]: https://internals.rust-lang.org/t/help-stabilize-a-subset-of-macros-2-0/7252
[issue]: https://github.com/rust-lang/rust/issues/50038
check stability of macro invocations
I haven't implemented tests yet but this should be a pretty solid prototype. I think as-implemented it will also stability-check macro invocations in the same crate, dunno if we want that or not.
I don't know if we want this to go through `rustc::middle::stability` or not, considering the information there wouldn't be available at the time of macro expansion (even for external crates, right?).
r? @nrc
closes#34079
cc @petrochenkov @durka @jseyfried #38356
1. Change the return type of `expand_invoc()` and its subroutines to
`Option<Expansion>` from `Expansion`.
2. Return `None` when expanding a derive invocation if the item cannot
have derive on it (in `expand_derive_invoc()`).
tweaks and fixes for doc(include)
This PR makes a handful of changes around `#[doc(include="file.md")]` (https://github.com/rust-lang/rust/issues/44732):
* Turns errors when loading files into full errors. This matches the original RFC text.
* Makes the `missing_docs` lint check for `#[doc(include="file.md")]` as well as regular `#[doc="text"]` attributes.
* Loads files included by `#[doc(include="file.md")]` into dep-info, mirroring the behavior of `include_str!()` and friends.
* Adds or modifies tests to check for all of these.
