use rustc_ast as ast;
use rustc_ast::visit::{self, AssocCtxt, FnCtxt, FnKind, Visitor};
use rustc_ast::{NodeId, PatKind, attr, token};
use rustc_feature::{AttributeGate, BUILTIN_ATTRIBUTE_MAP, BuiltinAttribute, Features, GateIssue};
use rustc_session::Session;
use rustc_session::parse::{feature_err, feature_err_issue, feature_warn};
use rustc_span::source_map::Spanned;
use rustc_span::{Span, Symbol, sym};
use rustc_target::spec::abi;
use thin_vec::ThinVec;
use crate::errors;
macro_rules! gate {
($visitor:expr, $feature:ident, $span:expr, $explain:expr) => {{
if !$visitor.features.$feature() && !$span.allows_unstable(sym::$feature) {
#[allow(rustc::untranslatable_diagnostic)] feature_err(&$visitor.sess, sym::$feature, $span, $explain).emit();
}
}};
($visitor:expr, $feature:ident, $span:expr, $explain:expr, $help:expr) => {{
if !$visitor.features.$feature() && !$span.allows_unstable(sym::$feature) {
#[allow(rustc::diagnostic_outside_of_impl)]
#[allow(rustc::untranslatable_diagnostic)]
feature_err(&$visitor.sess, sym::$feature, $span, $explain).with_help($help).emit();
}
}};
}
macro_rules! gate_alt {
($visitor:expr, $has_feature:expr, $name:expr, $span:expr, $explain:expr) => {{
if !$has_feature && !$span.allows_unstable($name) {
#[allow(rustc::untranslatable_diagnostic)] feature_err(&$visitor.sess, $name, $span, $explain).emit();
}
}};
}
macro_rules! gate_multi {
($visitor:expr, $feature:ident, $spans:expr, $explain:expr) => {{
if !$visitor.features.$feature() {
let spans: Vec<_> =
$spans.filter(|span| !span.allows_unstable(sym::$feature)).collect();
if !spans.is_empty() {
feature_err(&$visitor.sess, sym::$feature, spans, $explain).emit();
}
}
}};
}
macro_rules! gate_legacy {
($visitor:expr, $feature:ident, $span:expr, $explain:expr) => {{
if !$visitor.features.$feature() && !$span.allows_unstable(sym::$feature) {
feature_warn(&$visitor.sess, sym::$feature, $span, $explain);
}
}};
}
pub fn check_attribute(attr: &ast::Attribute, sess: &Session, features: &Features) {
PostExpansionVisitor { sess, features }.visit_attribute(attr)
}
struct PostExpansionVisitor<'a> {
sess: &'a Session,
features: &'a Features,
}
impl<'a> PostExpansionVisitor<'a> {
#[allow(rustc::untranslatable_diagnostic)] fn check_abi(&self, abi: ast::StrLit) {
let ast::StrLit { symbol_unescaped, span, .. } = abi;
match abi::is_enabled(self.features, span, symbol_unescaped.as_str()) {
Ok(()) => (),
Err(abi::AbiDisabled::Unstable { feature, explain }) => {
feature_err_issue(&self.sess, feature, span, GateIssue::Language, explain).emit();
}
Err(abi::AbiDisabled::Unrecognized) => {
if self.sess.opts.pretty.map_or(true, |ppm| ppm.needs_hir()) {
self.sess.dcx().span_delayed_bug(
span,
format!(
"unrecognized ABI not caught in lowering: {}",
symbol_unescaped.as_str()
),
);
}
}
}
}
fn check_extern(&self, ext: ast::Extern) {
if let ast::Extern::Explicit(abi, _) = ext {
self.check_abi(abi);
}
}
fn check_impl_trait(&self, ty: &ast::Ty, in_associated_ty: bool) {
struct ImplTraitVisitor<'a> {
vis: &'a PostExpansionVisitor<'a>,
in_associated_ty: bool,
}
impl Visitor<'_> for ImplTraitVisitor<'_> {
fn visit_ty(&mut self, ty: &ast::Ty) {
if let ast::TyKind::ImplTrait(..) = ty.kind {
if self.in_associated_ty {
gate!(
&self.vis,
impl_trait_in_assoc_type,
ty.span,
"`impl Trait` in associated types is unstable"
);
} else {
gate!(
&self.vis,
type_alias_impl_trait,
ty.span,
"`impl Trait` in type aliases is unstable"
);
}
}
visit::walk_ty(self, ty);
}
}
ImplTraitVisitor { vis: self, in_associated_ty }.visit_ty(ty);
}
fn check_late_bound_lifetime_defs(&self, params: &[ast::GenericParam]) {
let non_lt_param_spans = params.iter().filter_map(|param| match param.kind {
ast::GenericParamKind::Lifetime { .. } => None,
_ => Some(param.ident.span),
});
gate_multi!(
&self,
non_lifetime_binders,
non_lt_param_spans,
crate::fluent_generated::ast_passes_forbidden_non_lifetime_param
);
if self.features.non_lifetime_binders() {
let const_param_spans: Vec<_> = params
.iter()
.filter_map(|param| match param.kind {
ast::GenericParamKind::Const { .. } => Some(param.ident.span),
_ => None,
})
.collect();
if !const_param_spans.is_empty() {
self.sess.dcx().emit_err(errors::ForbiddenConstParam { const_param_spans });
}
}
for param in params {
if !param.bounds.is_empty() {
let spans: Vec<_> = param.bounds.iter().map(|b| b.span()).collect();
self.sess.dcx().emit_err(errors::ForbiddenBound { spans });
}
}
}
}
impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
fn visit_attribute(&mut self, attr: &ast::Attribute) {
let attr_info = attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name));
if let Some(BuiltinAttribute {
gate: AttributeGate::Gated(_, name, descr, has_feature),
..
}) = attr_info
{
gate_alt!(self, has_feature(self.features), *name, attr.span, *descr);
}
if attr.has_name(sym::doc) {
for meta_item_inner in attr.meta_item_list().unwrap_or_default() {
macro_rules! gate_doc { ($($s:literal { $($name:ident => $feature:ident)* })*) => {
$($(if meta_item_inner.has_name(sym::$name) {
let msg = concat!("`#[doc(", stringify!($name), ")]` is ", $s);
gate!(self, $feature, attr.span, msg);
})*)*
}}
gate_doc!(
"experimental" {
cfg => doc_cfg
cfg_hide => doc_cfg_hide
masked => doc_masked
notable_trait => doc_notable_trait
}
"meant for internal use only" {
keyword => rustdoc_internals
fake_variadic => rustdoc_internals
search_unbox => rustdoc_internals
}
);
}
}
if !self.features.staged_api() {
if attr.has_name(sym::unstable)
|| attr.has_name(sym::stable)
|| attr.has_name(sym::rustc_const_unstable)
|| attr.has_name(sym::rustc_const_stable)
|| attr.has_name(sym::rustc_default_body_unstable)
{
self.sess.dcx().emit_err(errors::StabilityOutsideStd { span: attr.span });
}
}
}
fn visit_item(&mut self, i: &'a ast::Item) {
match &i.kind {
ast::ItemKind::ForeignMod(foreign_module) => {
if let Some(abi) = foreign_module.abi {
self.check_abi(abi);
}
}
ast::ItemKind::Fn(..) => {
if attr::contains_name(&i.attrs, sym::start) {
gate!(
&self,
start,
i.span,
"`#[start]` functions are experimental and their signature may change \
over time"
);
}
}
ast::ItemKind::Struct(..) => {
for attr in attr::filter_by_name(&i.attrs, sym::repr) {
for item in attr.meta_item_list().unwrap_or_else(ThinVec::new) {
if item.has_name(sym::simd) {
gate!(
&self,
repr_simd,
attr.span,
"SIMD types are experimental and possibly buggy"
);
}
}
}
}
ast::ItemKind::Impl(box ast::Impl { polarity, defaultness, of_trait, .. }) => {
if let &ast::ImplPolarity::Negative(span) = polarity {
gate!(
&self,
negative_impls,
span.to(of_trait.as_ref().map_or(span, |t| t.path.span)),
"negative trait bounds are not yet fully implemented; \
use marker types for now"
);
}
if let ast::Defaultness::Default(_) = defaultness {
gate!(&self, specialization, i.span, "specialization is unstable");
}
}
ast::ItemKind::Trait(box ast::Trait { is_auto: ast::IsAuto::Yes, .. }) => {
gate!(
&self,
auto_traits,
i.span,
"auto traits are experimental and possibly buggy"
);
}
ast::ItemKind::TraitAlias(..) => {
gate!(&self, trait_alias, i.span, "trait aliases are experimental");
}
ast::ItemKind::MacroDef(ast::MacroDef { macro_rules: false, .. }) => {
let msg = "`macro` is experimental";
gate!(&self, decl_macro, i.span, msg);
}
ast::ItemKind::TyAlias(box ast::TyAlias { ty: Some(ty), .. }) => {
self.check_impl_trait(ty, false)
}
_ => {}
}
visit::walk_item(self, i);
}
fn visit_foreign_item(&mut self, i: &'a ast::ForeignItem) {
match i.kind {
ast::ForeignItemKind::Fn(..) | ast::ForeignItemKind::Static(..) => {
let link_name = attr::first_attr_value_str_by_name(&i.attrs, sym::link_name);
let links_to_llvm = link_name.is_some_and(|val| val.as_str().starts_with("llvm."));
if links_to_llvm {
gate!(
&self,
link_llvm_intrinsics,
i.span,
"linking to LLVM intrinsics is experimental"
);
}
}
ast::ForeignItemKind::TyAlias(..) => {
gate!(&self, extern_types, i.span, "extern types are experimental");
}
ast::ForeignItemKind::MacCall(..) => {}
}
visit::walk_item(self, i)
}
fn visit_ty(&mut self, ty: &'a ast::Ty) {
match &ty.kind {
ast::TyKind::BareFn(bare_fn_ty) => {
self.check_extern(bare_fn_ty.ext);
self.check_late_bound_lifetime_defs(&bare_fn_ty.generic_params);
}
ast::TyKind::Never => {
gate!(&self, never_type, ty.span, "the `!` type is experimental");
}
ast::TyKind::Pat(..) => {
gate!(&self, pattern_types, ty.span, "pattern types are unstable");
}
_ => {}
}
visit::walk_ty(self, ty)
}
fn visit_generics(&mut self, g: &'a ast::Generics) {
for predicate in &g.where_clause.predicates {
match &predicate.kind {
ast::WherePredicateKind::BoundPredicate(bound_pred) => {
self.check_late_bound_lifetime_defs(&bound_pred.bound_generic_params);
}
_ => {}
}
}
visit::walk_generics(self, g);
}
fn visit_fn_ret_ty(&mut self, ret_ty: &'a ast::FnRetTy) {
if let ast::FnRetTy::Ty(output_ty) = ret_ty {
if let ast::TyKind::Never = output_ty.kind {
} else {
self.visit_ty(output_ty)
}
}
}
fn visit_generic_args(&mut self, args: &'a ast::GenericArgs) {
if let ast::GenericArgs::Parenthesized(generic_args) = args
&& let ast::FnRetTy::Ty(ref ty) = generic_args.output
&& matches!(ty.kind, ast::TyKind::Never)
{
gate!(&self, never_type, ty.span, "the `!` type is experimental");
}
visit::walk_generic_args(self, args);
}
fn visit_expr(&mut self, e: &'a ast::Expr) {
match e.kind {
ast::ExprKind::TryBlock(_) => {
gate!(&self, try_blocks, e.span, "`try` expression is experimental");
}
ast::ExprKind::Lit(token::Lit { kind: token::LitKind::Float, suffix, .. }) => {
match suffix {
Some(sym::f16) => {
gate!(&self, f16, e.span, "the type `f16` is unstable")
}
Some(sym::f128) => {
gate!(&self, f128, e.span, "the type `f128` is unstable")
}
_ => (),
}
}
_ => {}
}
visit::walk_expr(self, e)
}
fn visit_pat(&mut self, pattern: &'a ast::Pat) {
match &pattern.kind {
PatKind::Slice(pats) => {
for pat in pats {
let inner_pat = match &pat.kind {
PatKind::Ident(.., Some(pat)) => pat,
_ => pat,
};
if let PatKind::Range(Some(_), None, Spanned { .. }) = inner_pat.kind {
gate!(
&self,
half_open_range_patterns_in_slices,
pat.span,
"`X..` patterns in slices are experimental"
);
}
}
}
PatKind::Box(..) => {
gate!(&self, box_patterns, pattern.span, "box pattern syntax is experimental");
}
_ => {}
}
visit::walk_pat(self, pattern)
}
fn visit_poly_trait_ref(&mut self, t: &'a ast::PolyTraitRef) {
self.check_late_bound_lifetime_defs(&t.bound_generic_params);
visit::walk_poly_trait_ref(self, t);
}
fn visit_fn(&mut self, fn_kind: FnKind<'a>, span: Span, _: NodeId) {
if let Some(header) = fn_kind.header() {
self.check_extern(header.ext);
}
if let FnKind::Closure(ast::ClosureBinder::For { generic_params, .. }, ..) = fn_kind {
self.check_late_bound_lifetime_defs(generic_params);
}
if fn_kind.ctxt() != Some(FnCtxt::Foreign) && fn_kind.decl().c_variadic() {
gate!(&self, c_variadic, span, "C-variadic functions are unstable");
}
visit::walk_fn(self, fn_kind)
}
fn visit_assoc_item(&mut self, i: &'a ast::AssocItem, ctxt: AssocCtxt) {
let is_fn = match &i.kind {
ast::AssocItemKind::Fn(_) => true,
ast::AssocItemKind::Type(box ast::TyAlias { ty, .. }) => {
if let (Some(_), AssocCtxt::Trait) = (ty, ctxt) {
gate!(
&self,
associated_type_defaults,
i.span,
"associated type defaults are unstable"
);
}
if let Some(ty) = ty {
self.check_impl_trait(ty, true);
}
false
}
_ => false,
};
if let ast::Defaultness::Default(_) = i.kind.defaultness() {
gate_alt!(
&self,
self.features.specialization() || (is_fn && self.features.min_specialization()),
sym::specialization,
i.span,
"specialization is unstable"
);
}
visit::walk_assoc_item(self, i, ctxt)
}
}
pub fn check_crate(krate: &ast::Crate, sess: &Session, features: &Features) {
maybe_stage_features(sess, features, krate);
check_incompatible_features(sess, features);
check_new_solver_banned_features(sess, features);
let mut visitor = PostExpansionVisitor { sess, features };
let spans = sess.psess.gated_spans.spans.borrow();
macro_rules! gate_all {
($gate:ident, $msg:literal) => {
if let Some(spans) = spans.get(&sym::$gate) {
for span in spans {
gate!(&visitor, $gate, *span, $msg);
}
}
};
($gate:ident, $msg:literal, $help:literal) => {
if let Some(spans) = spans.get(&sym::$gate) {
for span in spans {
gate!(&visitor, $gate, *span, $msg, $help);
}
}
};
}
gate_all!(
if_let_guard,
"`if let` guards are experimental",
"you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`"
);
gate_all!(let_chains, "`let` expressions in this position are unstable");
gate_all!(
async_trait_bounds,
"`async` trait bounds are unstable",
"use the desugared name of the async trait, such as `AsyncFn`"
);
gate_all!(async_for_loop, "`for await` loops are experimental");
gate_all!(
closure_lifetime_binder,
"`for<...>` binders for closures are experimental",
"consider removing `for<...>`"
);
gate_all!(more_qualified_paths, "usage of qualified paths in this context is experimental");
if let Some(spans) = spans.get(&sym::yield_expr) {
for span in spans {
if (!visitor.features.coroutines() && !span.allows_unstable(sym::coroutines))
&& (!visitor.features.gen_blocks() && !span.allows_unstable(sym::gen_blocks))
{
#[allow(rustc::untranslatable_diagnostic)]
feature_err(&visitor.sess, sym::coroutines, *span, "yield syntax is experimental")
.emit();
}
}
}
gate_all!(gen_blocks, "gen blocks are experimental");
gate_all!(const_trait_impl, "const trait impls are experimental");
gate_all!(
half_open_range_patterns_in_slices,
"half-open range patterns in slices are unstable"
);
gate_all!(inline_const_pat, "inline-const in pattern position is experimental");
gate_all!(associated_const_equality, "associated const equality is incomplete");
gate_all!(yeet_expr, "`do yeet` expression is experimental");
gate_all!(dyn_star, "`dyn*` trait objects are experimental");
gate_all!(const_closures, "const closures are experimental");
gate_all!(builtin_syntax, "`builtin #` syntax is unstable");
gate_all!(explicit_tail_calls, "`become` expression is experimental");
gate_all!(generic_const_items, "generic const items are experimental");
gate_all!(guard_patterns, "guard patterns are experimental", "consider using match arm guards");
gate_all!(default_field_values, "default values on fields are experimental");
gate_all!(fn_delegation, "functions delegation is not yet fully implemented");
gate_all!(postfix_match, "postfix match is experimental");
gate_all!(mut_ref, "mutable by-reference bindings are experimental");
gate_all!(global_registration, "global registration is experimental");
gate_all!(return_type_notation, "return type notation is experimental");
gate_all!(pin_ergonomics, "pinned reference syntax is experimental");
gate_all!(unsafe_fields, "`unsafe` fields are experimental");
gate_all!(unsafe_binders, "unsafe binder types are experimental");
if !visitor.features.never_patterns() {
if let Some(spans) = spans.get(&sym::never_patterns) {
for &span in spans {
if span.allows_unstable(sym::never_patterns) {
continue;
}
let sm = sess.source_map();
if let Ok(snippet) = sm.span_to_snippet(span)
&& snippet == "!"
{
#[allow(rustc::untranslatable_diagnostic)] feature_err(sess, sym::never_patterns, span, "`!` patterns are experimental")
.emit();
} else {
let suggestion = span.shrink_to_hi();
sess.dcx().emit_err(errors::MatchArmWithNoBody { span, suggestion });
}
}
}
}
if !visitor.features.negative_bounds() {
for &span in spans.get(&sym::negative_bounds).iter().copied().flatten() {
sess.dcx().emit_err(errors::NegativeBoundUnsupported { span });
}
}
macro_rules! gate_all_legacy_dont_use {
($gate:ident, $msg:literal) => {
for span in spans.get(&sym::$gate).unwrap_or(&vec![]) {
gate_legacy!(&visitor, $gate, *span, $msg);
}
};
}
gate_all_legacy_dont_use!(box_patterns, "box pattern syntax is experimental");
gate_all_legacy_dont_use!(trait_alias, "trait aliases are experimental");
gate_all_legacy_dont_use!(decl_macro, "`macro` is experimental");
gate_all_legacy_dont_use!(try_blocks, "`try` blocks are unstable");
gate_all_legacy_dont_use!(auto_traits, "`auto` traits are unstable");
visit::walk_crate(&mut visitor, krate);
}
fn maybe_stage_features(sess: &Session, features: &Features, krate: &ast::Crate) {
if sess.opts.unstable_features.is_nightly_build() {
return;
}
if features.enabled_features().is_empty() {
return;
}
let mut errored = false;
for attr in krate.attrs.iter().filter(|attr| attr.has_name(sym::feature)) {
let mut err = errors::FeatureOnNonNightly {
span: attr.span,
channel: option_env!("CFG_RELEASE_CHANNEL").unwrap_or("(unknown)"),
stable_features: vec![],
sugg: None,
};
let mut all_stable = true;
for ident in attr.meta_item_list().into_iter().flatten().flat_map(|nested| nested.ident()) {
let name = ident.name;
let stable_since = features
.enabled_lang_features()
.iter()
.find(|feat| feat.gate_name == name)
.map(|feat| feat.stable_since)
.flatten();
if let Some(since) = stable_since {
err.stable_features.push(errors::StableFeature { name, since });
} else {
all_stable = false;
}
}
if all_stable {
err.sugg = Some(attr.span);
}
sess.dcx().emit_err(err);
errored = true;
}
assert!(errored);
}
fn check_incompatible_features(sess: &Session, features: &Features) {
let enabled_lang_features =
features.enabled_lang_features().iter().map(|feat| (feat.gate_name, feat.attr_sp));
let enabled_lib_features =
features.enabled_lib_features().iter().map(|feat| (feat.gate_name, feat.attr_sp));
let enabled_features = enabled_lang_features.chain(enabled_lib_features);
for (f1, f2) in rustc_feature::INCOMPATIBLE_FEATURES
.iter()
.filter(|(f1, f2)| features.enabled(*f1) && features.enabled(*f2))
{
if let Some((f1_name, f1_span)) = enabled_features.clone().find(|(name, _)| name == f1) {
if let Some((f2_name, f2_span)) = enabled_features.clone().find(|(name, _)| name == f2)
{
let spans = vec![f1_span, f2_span];
sess.dcx().emit_err(errors::IncompatibleFeatures {
spans,
f1: f1_name,
f2: f2_name,
});
}
}
}
}
fn check_new_solver_banned_features(sess: &Session, features: &Features) {
if !sess.opts.unstable_opts.next_solver.globally {
return;
}
if let Some(gce_span) = features
.enabled_lang_features()
.iter()
.find(|feat| feat.gate_name == sym::generic_const_exprs)
.map(|feat| feat.attr_sp)
{
#[cfg_attr(not(bootstrap), allow(rustc::symbol_intern_string_literal))]
sess.dcx().emit_err(errors::IncompatibleFeatures {
spans: vec![gce_span],
f1: Symbol::intern("-Znext-solver=globally"),
f2: sym::generic_const_exprs,
});
}
}