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expand: Leave traces when expanding cfg attributes

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This commit is contained in:
Vadim Petrochenkov 2025-03-22 21:42:34 +03:00
parent 65899c06f1
commit 92d802eda6
24 changed files with 88 additions and 108 deletions
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3
compiler/rustc_ast_passes/src/ast_validation.rs
View file

@ -334,8 +334,7 @@ impl<'a> AstValidator<'a> {
.filter(|attr| {
let arr = [
sym::allow,
sym::cfg,
sym::cfg_attr,
sym::cfg_trace,
sym::cfg_attr_trace,
sym::deny,
sym::expect,

2
compiler/rustc_ast_pretty/src/pprust/state.rs
View file

@ -593,7 +593,7 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
}
fn print_attribute_inline(&mut self, attr: &ast::Attribute, is_inline: bool) -> bool {
if attr.has_name(sym::cfg_attr_trace) {
if attr.has_name(sym::cfg_trace) || attr.has_name(sym::cfg_attr_trace) {
// It's not a valid identifier, so avoid printing it
// to keep the printed code reasonably parse-able.
return false;

24
compiler/rustc_expand/src/config.rs
View file

@ -156,6 +156,19 @@ pub fn pre_configure_attrs(sess: &Session, attrs: &[Attribute]) -> ast::AttrVec
.collect()
}
pub(crate) fn attr_into_trace(mut attr: Attribute, trace_name: Symbol) -> Attribute {
match &mut attr.kind {
AttrKind::Normal(normal) => {
let NormalAttr { item, tokens } = &mut **normal;
item.path.segments[0].ident.name = trace_name;
// This makes the trace attributes unobservable to token-based proc macros.
*tokens = Some(LazyAttrTokenStream::new(AttrTokenStream::default()));
}
AttrKind::DocComment(..) => unreachable!(),
}
attr
}
#[macro_export]
macro_rules! configure {
($this:ident, $node:ident) => {
@ -280,16 +293,7 @@ impl<'a> StripUnconfigured<'a> {
// A trace attribute left in AST in place of the original `cfg_attr` attribute.
// It can later be used by lints or other diagnostics.
let mut trace_attr = cfg_attr.clone();
match &mut trace_attr.kind {
AttrKind::Normal(normal) => {
let NormalAttr { item, tokens } = &mut **normal;
item.path.segments[0].ident.name = sym::cfg_attr_trace;
// This makes the trace attributes unobservable to token-based proc macros.
*tokens = Some(LazyAttrTokenStream::new(AttrTokenStream::default()));
}
AttrKind::DocComment(..) => unreachable!(),
}
let trace_attr = attr_into_trace(cfg_attr.clone(), sym::cfg_attr_trace);
let Some((cfg_predicate, expanded_attrs)) =
rustc_parse::parse_cfg_attr(cfg_attr, &self.sess.psess)

13
compiler/rustc_expand/src/expand.rs
View file

@ -33,7 +33,7 @@ use rustc_span::{ErrorGuaranteed, FileName, Ident, LocalExpnId, Span, sym};
use smallvec::SmallVec;
use crate::base::*;
use crate::config::StripUnconfigured;
use crate::config::{StripUnconfigured, attr_into_trace};
use crate::errors::{
EmptyDelegationMac, GlobDelegationOutsideImpls, GlobDelegationTraitlessQpath, IncompleteParse,
RecursionLimitReached, RemoveExprNotSupported, RemoveNodeNotSupported, UnsupportedKeyValue,
@ -2003,7 +2003,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
let attr_name = attr.ident().unwrap().name;
// `#[cfg]` and `#[cfg_attr]` are special - they are
// eagerly evaluated.
if attr_name != sym::cfg && attr_name != sym::cfg_attr_trace {
if attr_name != sym::cfg_trace && attr_name != sym::cfg_attr_trace {
self.cx.sess.psess.buffer_lint(
UNUSED_ATTRIBUTES,
attr.span,
@ -2027,11 +2027,10 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
) -> (bool, Option<ast::MetaItem>) {
let (res, meta_item) = self.cfg().cfg_true(&attr);
if res {
// FIXME: `cfg(TRUE)` attributes do not currently remove themselves during expansion,
// and some tools like rustdoc and clippy rely on that. Find a way to remove them
// while keeping the tools working.
self.cx.expanded_inert_attrs.mark(&attr);
node.visit_attrs(|attrs| attrs.insert(pos, attr));
// A trace attribute left in AST in place of the original `cfg` attribute.
// It can later be used by lints or other diagnostics.
let trace_attr = attr_into_trace(attr, sym::cfg_trace);
node.visit_attrs(|attrs| attrs.insert(pos, trace_attr));
}
(res, meta_item)

12
compiler/rustc_feature/src/builtin_attrs.rs
View file

@ -760,10 +760,14 @@ pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
template!(Word, List: r#""...""#), DuplicatesOk,
EncodeCrossCrate::Yes, INTERNAL_UNSTABLE
),
// Trace that is left when a `cfg_attr` attribute is expanded.
// The attribute is not gated, to avoid stability errors, but it cannot be used in stable or
// unstable code directly because `sym::cfg_attr_trace` is not a valid identifier, it can only
// be generated by the compiler.
// Traces that are left when `cfg` and `cfg_attr` attributes are expanded.
// The attributes are not gated, to avoid stability errors, but they cannot be used in stable
// or unstable code directly because `sym::cfg_(attr_)trace` are not valid identifiers, they
// can only be generated by the compiler.
ungated!(
cfg_trace, Normal, template!(Word /* irrelevant */), DuplicatesOk,
EncodeCrossCrate::No
),
ungated!(
cfg_attr_trace, Normal, template!(Word /* irrelevant */), DuplicatesOk,
EncodeCrossCrate::No

9
compiler/rustc_parse/src/validate_attr.rs
View file

@ -16,7 +16,8 @@ use rustc_span::{Span, Symbol, sym};
use crate::{errors, parse_in};
pub fn check_attr(psess: &ParseSess, attr: &Attribute) {
if attr.is_doc_comment() || attr.has_name(sym::cfg_attr_trace) {
if attr.is_doc_comment() || attr.has_name(sym::cfg_trace) || attr.has_name(sym::cfg_attr_trace)
{
return;
}
@ -215,11 +216,7 @@ pub fn check_builtin_meta_item(
template: AttributeTemplate,
deny_unsafety: bool,
) {
// Some special attributes like `cfg` must be checked
// before the generic check, so we skip them here.
let should_skip = |name| name == sym::cfg;
if !should_skip(name) && !is_attr_template_compatible(&template, &meta.kind) {
if !is_attr_template_compatible(&template, &meta.kind) {
emit_malformed_attribute(psess, style, meta.span, name, template);
}

6
compiler/rustc_passes/src/check_attr.rs
View file

@ -272,6 +272,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
| sym::forbid
| sym::cfg
| sym::cfg_attr
| sym::cfg_trace
| sym::cfg_attr_trace
// need to be fixed
| sym::cfi_encoding // FIXME(cfi_encoding)
@ -574,8 +575,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
// NOTE: when making changes to this list, check that `error_codes/E0736.md` remains accurate
const ALLOW_LIST: &[rustc_span::Symbol] = &[
// conditional compilation
sym::cfg,
sym::cfg_attr,
sym::cfg_trace,
sym::cfg_attr_trace,
// testing (allowed here so better errors can be generated in `rustc_builtin_macros::test`)
sym::test,
@ -2656,7 +2656,7 @@ impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
// only `#[cfg]` and `#[cfg_attr]` are allowed, but it should be removed
// if we allow more attributes (e.g., tool attributes and `allow/deny/warn`)
// in where clauses. After that, only `self.check_attributes` should be enough.
const ATTRS_ALLOWED: &[Symbol] = &[sym::cfg, sym::cfg_attr, sym::cfg_attr_trace];
const ATTRS_ALLOWED: &[Symbol] = &[sym::cfg_trace, sym::cfg_attr_trace];
let spans = self
.tcx
.hir_attrs(where_predicate.hir_id)

2
compiler/rustc_query_system/src/ich/mod.rs
View file

@ -8,7 +8,7 @@ mod hcx;
mod impls_syntax;
pub const IGNORED_ATTRIBUTES: &[Symbol] = &[
sym::cfg,
sym::cfg_trace, // FIXME should this really be ignored?
sym::rustc_if_this_changed,
sym::rustc_then_this_would_need,
sym::rustc_dirty,

1
compiler/rustc_span/src/symbol.rs
View file

@ -623,6 +623,7 @@ symbols! {
cfg_target_has_atomic_equal_alignment,
cfg_target_thread_local,
cfg_target_vendor,
cfg_trace: "<cfg>", // must not be a valid identifier
cfg_ub_checks,
cfg_version,
cfi,

2
src/librustdoc/clean/mod.rs
View file

@ -2773,7 +2773,7 @@ fn add_without_unwanted_attributes<'hir>(
if ident == sym::doc {
filter_doc_attr(&mut normal.args, is_inline);
attrs.push((Cow::Owned(attr), import_parent));
} else if is_inline || ident != sym::cfg {
} else if is_inline || ident != sym::cfg_trace {
// If it's not a `cfg()` attribute, we keep it.
attrs.push((Cow::Owned(attr), import_parent));
}

2
src/librustdoc/clean/types.rs
View file

@ -1059,7 +1059,7 @@ pub(crate) fn extract_cfg_from_attrs<'a, I: Iterator<Item = &'a hir::Attribute>
// `doc(cfg())` overrides `cfg()`).
attrs
.clone()
.filter(|attr| attr.has_name(sym::cfg))
.filter(|attr| attr.has_name(sym::cfg_trace))
.filter_map(|attr| single(attr.meta_item_list()?))
.filter_map(|attr| Cfg::parse_without(attr.meta_item()?, hidden_cfg).ok().flatten())
.fold(Cfg::True, |cfg, new_cfg| cfg & new_cfg)

3
src/tools/clippy/clippy_lints/src/attrs/duplicated_attributes.rs
View file

@ -37,7 +37,6 @@ fn check_duplicated_attr(
let Some(ident) = attr.ident() else { return };
let name = ident.name;
if name == sym::doc
|| name == sym::cfg_attr
|| name == sym::cfg_attr_trace
|| name == sym::rustc_on_unimplemented
|| name == sym::reason {
@ -47,7 +46,7 @@ fn check_duplicated_attr(
return;
}
if let Some(direct_parent) = parent.last()
&& ["cfg", "cfg_attr"].contains(&direct_parent.as_str())
&& direct_parent == sym::cfg_trace.as_str()
&& [sym::all, sym::not, sym::any].contains(&name)
{
// FIXME: We don't correctly check `cfg`s for now, so if it's more complex than just a one

2
src/tools/clippy/clippy_lints/src/cfg_not_test.rs
View file

@ -32,7 +32,7 @@ declare_lint_pass!(CfgNotTest => [CFG_NOT_TEST]);
impl EarlyLintPass for CfgNotTest {
fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &rustc_ast::Attribute) {
if attr.has_name(rustc_span::sym::cfg) && contains_not_test(attr.meta_item_list().as_deref(), false) {
if attr.has_name(rustc_span::sym::cfg_trace) && contains_not_test(attr.meta_item_list().as_deref(), false) {
span_lint_and_then(
cx,
CFG_NOT_TEST,

2
src/tools/clippy/clippy_lints/src/methods/is_empty.rs
View file

@ -41,7 +41,7 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &'_ Expr<'_>, receiver: &Expr<'_
fn is_under_cfg(cx: &LateContext<'_>, id: HirId) -> bool {
cx.tcx
.hir_parent_id_iter(id)
.any(|id| cx.tcx.hir_attrs(id).iter().any(|attr| attr.has_name(sym::cfg)))
.any(|id| cx.tcx.hir_attrs(id).iter().any(|attr| attr.has_name(sym::cfg_trace)))
}
/// Similar to [`clippy_utils::expr_or_init`], but does not go up the chain if the initialization

8
src/tools/clippy/clippy_utils/src/lib.rs
View file

@ -2629,7 +2629,7 @@ pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>
pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
if let Res::Def(_, def_id) = path.res {
return cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr);
return cx.tcx.has_attr(def_id, sym::cfg_trace) || cx.tcx.has_attr(def_id, sym::cfg_attr);
}
}
false
@ -2699,7 +2699,7 @@ pub fn is_in_test_function(tcx: TyCtxt<'_>, id: HirId) -> bool {
/// use [`is_in_cfg_test`]
pub fn is_cfg_test(tcx: TyCtxt<'_>, id: HirId) -> bool {
tcx.hir_attrs(id).iter().any(|attr| {
if attr.has_name(sym::cfg)
if attr.has_name(sym::cfg_trace)
&& let Some(items) = attr.meta_item_list()
&& let [item] = &*items
&& item.has_name(sym::test)
@ -2723,11 +2723,11 @@ pub fn is_in_test(tcx: TyCtxt<'_>, hir_id: HirId) -> bool {
/// Checks if the item of any of its parents has `#[cfg(...)]` attribute applied.
pub fn inherits_cfg(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
tcx.has_attr(def_id, sym::cfg)
tcx.has_attr(def_id, sym::cfg_trace)
|| tcx
.hir_parent_iter(tcx.local_def_id_to_hir_id(def_id))
.flat_map(|(parent_id, _)| tcx.hir_attrs(parent_id))
.any(|attr| attr.has_name(sym::cfg))
.any(|attr| attr.has_name(sym::cfg_trace))
}
/// Walks up the HIR tree from the given expression in an attempt to find where the value is

3
tests/pretty/tests-are-sorted.pp
View file

@ -10,7 +10,6 @@ extern crate std;
//@ pp-exact:tests-are-sorted.pp
extern crate test;
#[cfg(test)]
#[rustc_test_marker = "m_test"]
#[doc(hidden)]
pub const m_test: test::TestDescAndFn =
@ -35,7 +34,6 @@ pub const m_test: test::TestDescAndFn =
fn m_test() {}
extern crate test;
#[cfg(test)]
#[rustc_test_marker = "z_test"]
#[doc(hidden)]
pub const z_test: test::TestDescAndFn =
@ -61,7 +59,6 @@ pub const z_test: test::TestDescAndFn =
fn z_test() {}
extern crate test;
#[cfg(test)]
#[rustc_test_marker = "a_test"]
#[doc(hidden)]
pub const a_test: test::TestDescAndFn =

1
tests/ui/conditional-compilation/cfg-attr-syntax-validation.rs
View file

@ -29,7 +29,6 @@ macro_rules! generate_s10 {
($expr: expr) => {
#[cfg(feature = $expr)]
//~^ ERROR expected unsuffixed literal, found expression `concat!("nonexistent")`
//~| ERROR expected unsuffixed literal, found expression `concat!("nonexistent")`
struct S10;
}
}

14
tests/ui/conditional-compilation/cfg-attr-syntax-validation.stderr
View file

@ -65,19 +65,7 @@ LL | generate_s10!(concat!("nonexistent"));
|
= note: this error originates in the macro `generate_s10` (in Nightly builds, run with -Z macro-backtrace for more info)
error: expected unsuffixed literal, found expression `concat!("nonexistent")`
--> $DIR/cfg-attr-syntax-validation.rs:30:25
|
LL | #[cfg(feature = $expr)]
| ^^^^^
...
LL | generate_s10!(concat!("nonexistent"));
| ------------------------------------- in this macro invocation
|
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
= note: this error originates in the macro `generate_s10` (in Nightly builds, run with -Z macro-backtrace for more info)
error: aborting due to 11 previous errors
error: aborting due to 10 previous errors
Some errors have detailed explanations: E0537, E0565.
For more information about an error, try `rustc --explain E0537`.

3
tests/ui/conditional-compilation/invalid-node-range-issue-129166.rs
View file

@ -1,11 +1,12 @@
// This was triggering an assertion failure in `NodeRange::new`.
//@ check-pass
#![feature(cfg_eval)]
#![feature(stmt_expr_attributes)]
fn f() -> u32 {
#[cfg_eval] #[cfg(not(FALSE))] 0
//~^ ERROR removing an expression is not supported in this position
}
fn main() {}

8
tests/ui/conditional-compilation/invalid-node-range-issue-129166.stderr
View file

@ -1,8 +0,0 @@
error: removing an expression is not supported in this position
--> $DIR/invalid-node-range-issue-129166.rs:7:17
|
LL | #[cfg_eval] #[cfg(not(FALSE))] 0
| ^^^^^^^^^^^^^^^^^^
error: aborting due to 1 previous error

2
tests/ui/parser/attribute/attr-bad-meta-4.rs
View file

@ -2,7 +2,6 @@ macro_rules! mac {
($attr_item: meta) => {
#[cfg($attr_item)]
//~^ ERROR expected unsuffixed literal, found `meta` metavariable
//~| ERROR expected unsuffixed literal, found `meta` metavariable
struct S;
}
}
@ -11,7 +10,6 @@ mac!(an(arbitrary token stream));
#[cfg(feature = -1)]
//~^ ERROR expected unsuffixed literal, found `-`
//~| ERROR expected unsuffixed literal, found `-`
fn handler() {}
fn main() {}

24
tests/ui/parser/attribute/attr-bad-meta-4.stderr
View file

@ -1,5 +1,5 @@
error: expected unsuffixed literal, found `-`
--> $DIR/attr-bad-meta-4.rs:12:17
--> $DIR/attr-bad-meta-4.rs:11:17
|
LL | #[cfg(feature = -1)]
| ^
@ -15,25 +15,5 @@ LL | mac!(an(arbitrary token stream));
|
= note: this error originates in the macro `mac` (in Nightly builds, run with -Z macro-backtrace for more info)
error: expected unsuffixed literal, found `meta` metavariable
--> $DIR/attr-bad-meta-4.rs:3:15
|
LL | #[cfg($attr_item)]
| ^^^^^^^^^^
...
LL | mac!(an(arbitrary token stream));
| -------------------------------- in this macro invocation
|
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
= note: this error originates in the macro `mac` (in Nightly builds, run with -Z macro-backtrace for more info)
error: expected unsuffixed literal, found `-`
--> $DIR/attr-bad-meta-4.rs:12:17
|
LL | #[cfg(feature = -1)]
| ^
|
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
error: aborting due to 4 previous errors
error: aborting due to 2 previous errors

10
tests/ui/proc-macro/cfg-attr-trace.rs
View file

@ -3,6 +3,7 @@
//@ check-pass
//@ proc-macro: test-macros.rs
#![feature(cfg_boolean_literals)]
#![feature(cfg_eval)]
#[macro_use]
@ -10,8 +11,13 @@ extern crate test_macros;
#[cfg_eval]
#[test_macros::print_attr]
#[cfg_attr(FALSE, test_macros::print_attr)]
#[cfg_attr(all(), test_macros::print_attr)]
#[cfg_attr(false, test_macros::print_attr)]
#[cfg_attr(true, test_macros::print_attr)]
struct S;
#[cfg_eval]
#[test_macros::print_attr]
#[cfg(true)]
struct Z;
fn main() {}

40
tests/ui/proc-macro/cfg-attr-trace.stdout
View file

@ -4,59 +4,75 @@ PRINT-ATTR INPUT (DEBUG): TokenStream [
Punct {
ch: '#',
spacing: Alone,
span: #0 bytes(271..272),
span: #0 bytes(305..306),
},
Group {
delimiter: Bracket,
stream: TokenStream [
Ident {
ident: "test_macros",
span: #0 bytes(289..300),
span: #0 bytes(322..333),
},
Punct {
ch: ':',
spacing: Joint,
span: #0 bytes(300..301),
span: #0 bytes(333..334),
},
Punct {
ch: ':',
spacing: Alone,
span: #0 bytes(301..302),
span: #0 bytes(334..335),
},
Ident {
ident: "print_attr",
span: #0 bytes(302..312),
span: #0 bytes(335..345),
},
],
span: #0 bytes(272..314),
span: #0 bytes(306..347),
},
Ident {
ident: "struct",
span: #0 bytes(315..321),
span: #0 bytes(348..354),
},
Ident {
ident: "S",
span: #0 bytes(322..323),
span: #0 bytes(355..356),
},
Punct {
ch: ';',
spacing: Alone,
span: #0 bytes(323..324),
span: #0 bytes(356..357),
},
]
PRINT-ATTR INPUT (DISPLAY): struct S;
PRINT-ATTR INPUT (DEBUG): TokenStream [
Ident {
ident: "struct",
span: #0 bytes(315..321),
span: #0 bytes(348..354),
},
Ident {
ident: "S",
span: #0 bytes(322..323),
span: #0 bytes(355..356),
},
Punct {
ch: ';',
spacing: Alone,
span: #0 bytes(323..324),
span: #0 bytes(356..357),
},
]
PRINT-ATTR INPUT (DISPLAY): struct Z;
PRINT-ATTR INPUT (DEBUG): TokenStream [
Ident {
ident: "struct",
span: #0 bytes(411..417),
},
Ident {
ident: "Z",
span: #0 bytes(418..419),
},
Punct {
ch: ';',
spacing: Alone,
span: #0 bytes(419..420),
},
]