use rustc_ast as ast;
use rustc_ast::visit::{self, AssocCtxt, FnCtxt, FnKind, Visitor};
use rustc_ast::{AssocTyConstraint, AssocTyConstraintKind, NodeId};
use rustc_ast::{GenericParam, GenericParamKind, PatKind, RangeEnd, VariantData};
use rustc_errors::struct_span_err;
use rustc_feature::{AttributeGate, BUILTIN_ATTRIBUTE_MAP};
use rustc_feature::{Features, GateIssue};
use rustc_session::parse::{feature_err, feature_err_issue};
use rustc_session::Session;
use rustc_span::source_map::Spanned;
use rustc_span::symbol::{sym, Symbol};
use rustc_span::Span;
use tracing::debug;
macro_rules! gate_feature_fn {
($visitor: expr, $has_feature: expr, $span: expr, $name: expr, $explain: expr) => {{
let (visitor, has_feature, span, name, explain) =
(&*$visitor, $has_feature, $span, $name, $explain);
let has_feature: bool = has_feature(visitor.features);
debug!("gate_feature(feature = {:?}, span = {:?}); has? {}", name, span, has_feature);
if !has_feature && !span.allows_unstable($name) {
feature_err_issue(&visitor.sess.parse_sess, name, span, GateIssue::Language, explain)
.emit();
}
}};
}
macro_rules! gate_feature_post {
($visitor: expr, $feature: ident, $span: expr, $explain: expr) => {
gate_feature_fn!($visitor, |x: &Features| x.$feature, $span, sym::$feature, $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> {
fn check_abi(&self, abi: ast::StrLit) {
let ast::StrLit { symbol_unescaped, span, .. } = abi;
match &*symbol_unescaped.as_str() {
"Rust" | "C" | "cdecl" | "stdcall" | "fastcall" | "aapcs" | "win64" | "sysv64"
| "system" => {}
"rust-intrinsic" => {
gate_feature_post!(&self, intrinsics, span, "intrinsics are subject to change");
}
"platform-intrinsic" => {
gate_feature_post!(
&self,
platform_intrinsics,
span,
"platform intrinsics are experimental and possibly buggy"
);
}
"vectorcall" => {
gate_feature_post!(
&self,
abi_vectorcall,
span,
"vectorcall is experimental and subject to change"
);
}
"thiscall" => {
gate_feature_post!(
&self,
abi_thiscall,
span,
"thiscall is experimental and subject to change"
);
}
"rust-call" => {
gate_feature_post!(
&self,
unboxed_closures,
span,
"rust-call ABI is subject to change"
);
}
"ptx-kernel" => {
gate_feature_post!(
&self,
abi_ptx,
span,
"PTX ABIs are experimental and subject to change"
);
}
"unadjusted" => {
gate_feature_post!(
&self,
abi_unadjusted,
span,
"unadjusted ABI is an implementation detail and perma-unstable"
);
}
"msp430-interrupt" => {
gate_feature_post!(
&self,
abi_msp430_interrupt,
span,
"msp430-interrupt ABI is experimental and subject to change"
);
}
"x86-interrupt" => {
gate_feature_post!(
&self,
abi_x86_interrupt,
span,
"x86-interrupt ABI is experimental and subject to change"
);
}
"amdgpu-kernel" => {
gate_feature_post!(
&self,
abi_amdgpu_kernel,
span,
"amdgpu-kernel ABI is experimental and subject to change"
);
}
"avr-interrupt" | "avr-non-blocking-interrupt" => {
gate_feature_post!(
&self,
abi_avr_interrupt,
span,
"avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change"
);
}
"efiapi" => {
gate_feature_post!(
&self,
abi_efiapi,
span,
"efiapi ABI is experimental and subject to change"
);
}
abi => self
.sess
.parse_sess
.span_diagnostic
.delay_span_bug(span, &format!("unrecognized ABI not caught in lowering: {}", abi)),
}
}
fn check_extern(&self, ext: ast::Extern) {
if let ast::Extern::Explicit(abi) = ext {
self.check_abi(abi);
}
}
fn maybe_report_invalid_custom_discriminants(&self, variants: &[ast::Variant]) {
let has_fields = variants.iter().any(|variant| match variant.data {
VariantData::Tuple(..) | VariantData::Struct(..) => true,
VariantData::Unit(..) => false,
});
let discriminant_spans = variants
.iter()
.filter(|variant| match variant.data {
VariantData::Tuple(..) | VariantData::Struct(..) => false,
VariantData::Unit(..) => true,
})
.filter_map(|variant| variant.disr_expr.as_ref().map(|c| c.value.span))
.collect::<Vec<_>>();
if !discriminant_spans.is_empty() && has_fields {
let mut err = feature_err(
&self.sess.parse_sess,
sym::arbitrary_enum_discriminant,
discriminant_spans.clone(),
"custom discriminant values are not allowed in enums with tuple or struct variants",
);
for sp in discriminant_spans {
err.span_label(sp, "disallowed custom discriminant");
}
for variant in variants.iter() {
match &variant.data {
VariantData::Struct(..) => {
err.span_label(variant.span, "struct variant defined here");
}
VariantData::Tuple(..) => {
err.span_label(variant.span, "tuple variant defined here");
}
VariantData::Unit(..) => {}
}
}
err.emit();
}
}
fn check_gat(&self, generics: &ast::Generics, span: Span) {
if !generics.params.is_empty() {
gate_feature_post!(
&self,
generic_associated_types,
span,
"generic associated types are unstable"
);
}
if !generics.where_clause.predicates.is_empty() {
gate_feature_post!(
&self,
generic_associated_types,
span,
"where clauses on associated types are unstable"
);
}
}
fn check_impl_trait(&self, ty: &ast::Ty) {
struct ImplTraitVisitor<'a> {
vis: &'a PostExpansionVisitor<'a>,
}
impl Visitor<'_> for ImplTraitVisitor<'_> {
fn visit_ty(&mut self, ty: &ast::Ty) {
if let ast::TyKind::ImplTrait(..) = ty.kind {
gate_feature_post!(
&self.vis,
type_alias_impl_trait,
ty.span,
"`impl Trait` in type aliases is unstable"
);
}
visit::walk_ty(self, ty);
}
}
ImplTraitVisitor { vis: self }.visit_ty(ty);
}
}
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)).map(|a| **a);
if let Some((.., AttributeGate::Gated(_, name, descr, has_feature))) = attr_info {
gate_feature_fn!(self, has_feature, attr.span, name, descr);
}
if self.sess.check_name(attr, sym::doc) {
for nested_meta in attr.meta_item_list().unwrap_or_default() {
macro_rules! gate_doc { ($($name:ident => $feature:ident)*) => {
$(if nested_meta.has_name(sym::$name) {
let msg = concat!("`#[doc(", stringify!($name), ")]` is experimental");
gate_feature_post!(self, $feature, attr.span, msg);
})*
}}
gate_doc!(
include => external_doc
cfg => doc_cfg
masked => doc_masked
spotlight => doc_spotlight
keyword => doc_keyword
);
}
}
}
fn visit_name(&mut self, sp: Span, name: Symbol) {
if !name.as_str().is_ascii() {
gate_feature_post!(
&self,
non_ascii_idents,
self.sess.parse_sess.source_map().guess_head_span(sp),
"non-ascii idents are not fully supported"
);
}
}
fn visit_item(&mut self, i: &'a ast::Item) {
match i.kind {
ast::ItemKind::ForeignMod(ref foreign_module) => {
if let Some(abi) = foreign_module.abi {
self.check_abi(abi);
}
}
ast::ItemKind::Fn(..) => {
if self.sess.contains_name(&i.attrs[..], sym::plugin_registrar) {
gate_feature_post!(
&self,
plugin_registrar,
i.span,
"compiler plugins are experimental and possibly buggy"
);
}
if self.sess.contains_name(&i.attrs[..], sym::start) {
gate_feature_post!(
&self,
start,
i.span,
"`#[start]` functions are experimental \
and their signature may change \
over time"
);
}
if self.sess.contains_name(&i.attrs[..], sym::main) {
gate_feature_post!(
&self,
main,
i.span,
"declaration of a non-standard `#[main]` \
function may change over time, for now \
a top-level `fn main()` is required"
);
}
}
ast::ItemKind::Struct(..) => {
for attr in self.sess.filter_by_name(&i.attrs[..], sym::repr) {
for item in attr.meta_item_list().unwrap_or_else(Vec::new) {
if item.has_name(sym::simd) {
gate_feature_post!(
&self,
repr_simd,
attr.span,
"SIMD types are experimental and possibly buggy"
);
}
}
}
}
ast::ItemKind::Enum(ast::EnumDef { ref variants, .. }, ..) => {
for variant in variants {
match (&variant.data, &variant.disr_expr) {
(ast::VariantData::Unit(..), _) => {}
(_, Some(disr_expr)) => gate_feature_post!(
&self,
arbitrary_enum_discriminant,
disr_expr.value.span,
"discriminants on non-unit variants are experimental"
),
_ => {}
}
}
let has_feature = self.features.arbitrary_enum_discriminant;
if !has_feature && !i.span.allows_unstable(sym::arbitrary_enum_discriminant) {
self.maybe_report_invalid_custom_discriminants(&variants);
}
}
ast::ItemKind::Impl { polarity, defaultness, ref of_trait, .. } => {
if let ast::ImplPolarity::Negative(span) = polarity {
gate_feature_post!(
&self,
negative_impls,
span.to(of_trait.as_ref().map(|t| t.path.span).unwrap_or(span)),
"negative trait bounds are not yet fully implemented; \
use marker types for now"
);
}
if let ast::Defaultness::Default(_) = defaultness {
gate_feature_post!(&self, specialization, i.span, "specialization is unstable");
}
}
ast::ItemKind::Trait(ast::IsAuto::Yes, ..) => {
gate_feature_post!(
&self,
auto_traits,
i.span,
"auto traits are experimental and possibly buggy"
);
}
ast::ItemKind::TraitAlias(..) => {
gate_feature_post!(&self, trait_alias, i.span, "trait aliases are experimental");
}
ast::ItemKind::MacroDef(ast::MacroDef { macro_rules: false, .. }) => {
let msg = "`macro` is experimental";
gate_feature_post!(&self, decl_macro, i.span, msg);
}
ast::ItemKind::TyAlias(_, _, _, Some(ref ty)) => self.check_impl_trait(&ty),
_ => {}
}
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 = self.sess.first_attr_value_str_by_name(&i.attrs, sym::link_name);
let links_to_llvm = match link_name {
Some(val) => val.as_str().starts_with("llvm."),
_ => false,
};
if links_to_llvm {
gate_feature_post!(
&self,
link_llvm_intrinsics,
i.span,
"linking to LLVM intrinsics is experimental"
);
}
}
ast::ForeignItemKind::TyAlias(..) => {
gate_feature_post!(&self, extern_types, i.span, "extern types are experimental");
}
ast::ForeignItemKind::MacCall(..) => {}
}
visit::walk_foreign_item(self, i)
}
fn visit_ty(&mut self, ty: &'a ast::Ty) {
match ty.kind {
ast::TyKind::BareFn(ref bare_fn_ty) => {
self.check_extern(bare_fn_ty.ext);
}
ast::TyKind::Never => {
gate_feature_post!(&self, never_type, ty.span, "the `!` type is experimental");
}
_ => {}
}
visit::walk_ty(self, ty)
}
fn visit_fn_ret_ty(&mut self, ret_ty: &'a ast::FnRetTy) {
if let ast::FnRetTy::Ty(ref output_ty) = *ret_ty {
if let ast::TyKind::Never = output_ty.kind {
} else {
self.visit_ty(output_ty)
}
}
}
fn visit_expr(&mut self, e: &'a ast::Expr) {
match e.kind {
ast::ExprKind::Box(_) => {
gate_feature_post!(
&self,
box_syntax,
e.span,
"box expression syntax is experimental; you can call `Box::new` instead"
);
}
ast::ExprKind::Type(..) => {
if self.sess.parse_sess.span_diagnostic.err_count() == 0 {
gate_feature_post!(
&self,
type_ascription,
e.span,
"type ascription is experimental"
);
}
}
ast::ExprKind::TryBlock(_) => {
gate_feature_post!(&self, try_blocks, e.span, "`try` expression is experimental");
}
ast::ExprKind::Block(_, opt_label) => {
if let Some(label) = opt_label {
gate_feature_post!(
&self,
label_break_value,
label.ident.span,
"labels on blocks are unstable"
);
}
}
_ => {}
}
visit::walk_expr(self, e)
}
fn visit_pat(&mut self, pattern: &'a ast::Pat) {
match &pattern.kind {
PatKind::Box(..) => {
gate_feature_post!(
&self,
box_patterns,
pattern.span,
"box pattern syntax is experimental"
);
}
PatKind::Range(_, _, Spanned { node: RangeEnd::Excluded, .. }) => {
gate_feature_post!(
&self,
exclusive_range_pattern,
pattern.span,
"exclusive range pattern syntax is experimental"
);
}
_ => {}
}
visit::walk_pat(self, pattern)
}
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 (ast::Const::Yes(_), ast::Extern::Implicit)
| (ast::Const::Yes(_), ast::Extern::Explicit(_)) = (header.constness, header.ext)
{
gate_feature_post!(
&self,
const_extern_fn,
span,
"`const extern fn` definitions are unstable"
);
}
}
if fn_kind.ctxt() != Some(FnCtxt::Foreign) && fn_kind.decl().c_variadic() {
gate_feature_post!(&self, c_variadic, span, "C-variadic functions are unstable");
}
visit::walk_fn(self, fn_kind, span)
}
fn visit_generic_param(&mut self, param: &'a GenericParam) {
if let GenericParamKind::Const { .. } = param.kind {
gate_feature_fn!(
&self,
|x: &Features| x.const_generics || x.min_const_generics,
param.ident.span,
sym::min_const_generics,
"const generics are unstable"
);
}
visit::walk_generic_param(self, param)
}
fn visit_assoc_ty_constraint(&mut self, constraint: &'a AssocTyConstraint) {
if let AssocTyConstraintKind::Bound { .. } = constraint.kind {
gate_feature_post!(
&self,
associated_type_bounds,
constraint.span,
"associated type bounds are unstable"
)
}
visit::walk_assoc_ty_constraint(self, constraint)
}
fn visit_assoc_item(&mut self, i: &'a ast::AssocItem, ctxt: AssocCtxt) {
let is_fn = match i.kind {
ast::AssocItemKind::Fn(_, ref sig, _, _) => {
if let (ast::Const::Yes(_), AssocCtxt::Trait) = (sig.header.constness, ctxt) {
gate_feature_post!(&self, const_fn, i.span, "const fn is unstable");
}
true
}
ast::AssocItemKind::TyAlias(_, ref generics, _, ref ty) => {
if let (Some(_), AssocCtxt::Trait) = (ty, ctxt) {
gate_feature_post!(
&self,
associated_type_defaults,
i.span,
"associated type defaults are unstable"
);
}
if let Some(ty) = ty {
self.check_impl_trait(ty);
}
self.check_gat(generics, i.span);
false
}
_ => false,
};
if let ast::Defaultness::Default(_) = i.kind.defaultness() {
gate_feature_fn!(
&self,
|x: &Features| x.specialization || (is_fn && x.min_specialization),
i.span,
sym::specialization,
"specialization is unstable"
);
}
visit::walk_assoc_item(self, i, ctxt)
}
fn visit_vis(&mut self, vis: &'a ast::Visibility) {
if let ast::VisibilityKind::Crate(ast::CrateSugar::JustCrate) = vis.kind {
gate_feature_post!(
&self,
crate_visibility_modifier,
vis.span,
"`crate` visibility modifier is experimental"
);
}
visit::walk_vis(self, vis)
}
}
pub fn check_crate(krate: &ast::Crate, sess: &Session) {
maybe_stage_features(sess, krate);
check_incompatible_features(sess);
let mut visitor = PostExpansionVisitor { sess, features: &sess.features_untracked() };
let spans = sess.parse_sess.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_feature_post!(&visitor, $gate, *span, $msg);
}
}
};
}
gate_all!(if_let_guard, "`if let` guard is not implemented");
gate_all!(let_chains, "`let` expressions in this position are experimental");
gate_all!(async_closure, "async closures are unstable");
gate_all!(generators, "yield syntax is experimental");
gate_all!(or_patterns, "or-patterns syntax is experimental");
gate_all!(raw_ref_op, "raw address of syntax is experimental");
gate_all!(const_trait_bound_opt_out, "`?const` on trait bounds is experimental");
gate_all!(const_trait_impl, "const trait impls are experimental");
gate_all!(half_open_range_patterns, "half-open range patterns are unstable");
gate_all!(inline_const, "inline-const is experimental");
if sess.parse_sess.span_diagnostic.err_count() == 0 {
gate_all!(destructuring_assignment, "destructuring assignments are unstable");
}
macro_rules! gate_all {
($gate:ident, $msg:literal) => {
if false {
for span in spans.get(&sym::$gate).unwrap_or(&vec![]) {
gate_feature_post!(&visitor, $gate, *span, $msg);
}
}
};
}
gate_all!(trait_alias, "trait aliases are experimental");
gate_all!(associated_type_bounds, "associated type bounds are unstable");
gate_all!(crate_visibility_modifier, "`crate` visibility modifier is experimental");
gate_all!(const_generics, "const generics are unstable");
gate_all!(decl_macro, "`macro` is experimental");
gate_all!(box_patterns, "box pattern syntax is experimental");
gate_all!(exclusive_range_pattern, "exclusive range pattern syntax is experimental");
gate_all!(try_blocks, "`try` blocks are unstable");
gate_all!(label_break_value, "labels on blocks are unstable");
gate_all!(box_syntax, "box expression syntax is experimental; you can call `Box::new` instead");
if sess.parse_sess.span_diagnostic.err_count() == 0 {
gate_all!(type_ascription, "type ascription is experimental");
}
visit::walk_crate(&mut visitor, krate);
}
fn maybe_stage_features(sess: &Session, krate: &ast::Crate) {
if !sess.opts.unstable_features.is_nightly_build() {
for attr in krate.attrs.iter().filter(|attr| sess.check_name(attr, sym::feature)) {
struct_span_err!(
sess.parse_sess.span_diagnostic,
attr.span,
E0554,
"`#![feature]` may not be used on the {} release channel",
option_env!("CFG_RELEASE_CHANNEL").unwrap_or("(unknown)")
)
.emit();
}
}
}
fn check_incompatible_features(sess: &Session) {
let features = sess.features_untracked();
let declared_features = features
.declared_lang_features
.iter()
.copied()
.map(|(name, span, _)| (name, span))
.chain(features.declared_lib_features.iter().copied());
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)) = declared_features.clone().find(|(name, _)| name == f1) {
if let Some((f2_name, f2_span)) = declared_features.clone().find(|(name, _)| name == f2)
{
let spans = vec![f1_span, f2_span];
sess.struct_span_err(
spans.clone(),
&format!(
"features `{}` and `{}` are incompatible, using them at the same time \
is not allowed",
f1_name, f2_name
),
)
.help("remove one of these features")
.emit();
}
}
}
}