diff options
Diffstat (limited to 'compiler/rustc_ast_passes')
| -rw-r--r-- | compiler/rustc_ast_passes/Cargo.toml | 18 | ||||
| -rw-r--r-- | compiler/rustc_ast_passes/src/ast_validation.rs | 1909 | ||||
| -rw-r--r-- | compiler/rustc_ast_passes/src/feature_gate.rs | 901 | ||||
| -rw-r--r-- | compiler/rustc_ast_passes/src/lib.rs | 18 | ||||
| -rw-r--r-- | compiler/rustc_ast_passes/src/node_count.rs | 135 | ||||
| -rw-r--r-- | compiler/rustc_ast_passes/src/show_span.rs | 65 |
6 files changed, 3046 insertions, 0 deletions
diff --git a/compiler/rustc_ast_passes/Cargo.toml b/compiler/rustc_ast_passes/Cargo.toml new file mode 100644 index 000000000..22742b2ad --- /dev/null +++ b/compiler/rustc_ast_passes/Cargo.toml @@ -0,0 +1,18 @@ +[package] +name = "rustc_ast_passes" +version = "0.0.0" +edition = "2021" + +[dependencies] +itertools = "0.10.1" +tracing = "0.1" +rustc_ast_pretty = { path = "../rustc_ast_pretty" } +rustc_attr = { path = "../rustc_attr" } +rustc_data_structures = { path = "../rustc_data_structures" } +rustc_errors = { path = "../rustc_errors" } +rustc_feature = { path = "../rustc_feature" } +rustc_parse = { path = "../rustc_parse" } +rustc_session = { path = "../rustc_session" } +rustc_span = { path = "../rustc_span" } +rustc_target = { path = "../rustc_target" } +rustc_ast = { path = "../rustc_ast" } diff --git a/compiler/rustc_ast_passes/src/ast_validation.rs b/compiler/rustc_ast_passes/src/ast_validation.rs new file mode 100644 index 000000000..2d9d0073f --- /dev/null +++ b/compiler/rustc_ast_passes/src/ast_validation.rs @@ -0,0 +1,1909 @@ +// Validate AST before lowering it to HIR. +// +// This pass is supposed to catch things that fit into AST data structures, +// but not permitted by the language. It runs after expansion when AST is frozen, +// so it can check for erroneous constructions produced by syntax extensions. +// This pass is supposed to perform only simple checks not requiring name resolution +// or type checking or some other kind of complex analysis. + +use itertools::{Either, Itertools}; +use rustc_ast::ptr::P; +use rustc_ast::visit::{self, AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor}; +use rustc_ast::walk_list; +use rustc_ast::*; +use rustc_ast_pretty::pprust::{self, State}; +use rustc_data_structures::fx::FxHashMap; +use rustc_errors::{ + error_code, pluralize, struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed, +}; +use rustc_parse::validate_attr; +use rustc_session::lint::builtin::{ + DEPRECATED_WHERE_CLAUSE_LOCATION, MISSING_ABI, PATTERNS_IN_FNS_WITHOUT_BODY, +}; +use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer}; +use rustc_session::Session; +use rustc_span::source_map::Spanned; +use rustc_span::symbol::{kw, sym, Ident}; +use rustc_span::Span; +use rustc_target::spec::abi; +use std::mem; +use std::ops::{Deref, DerefMut}; + +const MORE_EXTERN: &str = + "for more information, visit https://doc.rust-lang.org/std/keyword.extern.html"; + +/// Is `self` allowed semantically as the first parameter in an `FnDecl`? +enum SelfSemantic { + Yes, + No, +} + +struct AstValidator<'a> { + session: &'a Session, + + /// The span of the `extern` in an `extern { ... }` block, if any. + extern_mod: Option<&'a Item>, + + /// Are we inside a trait impl? + in_trait_impl: bool, + + in_const_trait_impl: bool, + + has_proc_macro_decls: bool, + + /// Used to ban nested `impl Trait`, e.g., `impl Into<impl Debug>`. + /// Nested `impl Trait` _is_ allowed in associated type position, + /// e.g., `impl Iterator<Item = impl Debug>`. + outer_impl_trait: Option<Span>, + + is_tilde_const_allowed: bool, + + /// Used to ban `impl Trait` in path projections like `<impl Iterator>::Item` + /// or `Foo::Bar<impl Trait>` + is_impl_trait_banned: bool, + + /// Used to ban associated type bounds (i.e., `Type<AssocType: Bounds>`) in + /// certain positions. + is_assoc_ty_bound_banned: bool, + + /// See [ForbiddenLetReason] + forbidden_let_reason: Option<ForbiddenLetReason>, + + lint_buffer: &'a mut LintBuffer, +} + +impl<'a> AstValidator<'a> { + fn with_in_trait_impl( + &mut self, + is_in: bool, + constness: Option<Const>, + f: impl FnOnce(&mut Self), + ) { + let old = mem::replace(&mut self.in_trait_impl, is_in); + let old_const = + mem::replace(&mut self.in_const_trait_impl, matches!(constness, Some(Const::Yes(_)))); + f(self); + self.in_trait_impl = old; + self.in_const_trait_impl = old_const; + } + + fn with_banned_impl_trait(&mut self, f: impl FnOnce(&mut Self)) { + let old = mem::replace(&mut self.is_impl_trait_banned, true); + f(self); + self.is_impl_trait_banned = old; + } + + fn with_tilde_const(&mut self, allowed: bool, f: impl FnOnce(&mut Self)) { + let old = mem::replace(&mut self.is_tilde_const_allowed, allowed); + f(self); + self.is_tilde_const_allowed = old; + } + + fn with_tilde_const_allowed(&mut self, f: impl FnOnce(&mut Self)) { + self.with_tilde_const(true, f) + } + + fn with_banned_tilde_const(&mut self, f: impl FnOnce(&mut Self)) { + self.with_tilde_const(false, f) + } + + fn with_let_management( + &mut self, + forbidden_let_reason: Option<ForbiddenLetReason>, + f: impl FnOnce(&mut Self, Option<ForbiddenLetReason>), + ) { + let old = mem::replace(&mut self.forbidden_let_reason, forbidden_let_reason); + f(self, old); + self.forbidden_let_reason = old; + } + + /// Emits an error banning the `let` expression provided in the given location. + fn ban_let_expr(&self, expr: &'a Expr, forbidden_let_reason: ForbiddenLetReason) { + let sess = &self.session; + if sess.opts.unstable_features.is_nightly_build() { + let err = "`let` expressions are not supported here"; + let mut diag = sess.struct_span_err(expr.span, err); + diag.note("only supported directly in conditions of `if` and `while` expressions"); + match forbidden_let_reason { + ForbiddenLetReason::GenericForbidden => {} + ForbiddenLetReason::NotSupportedOr(span) => { + diag.span_note( + span, + "`||` operators are not supported in let chain expressions", + ); + } + ForbiddenLetReason::NotSupportedParentheses(span) => { + diag.span_note( + span, + "`let`s wrapped in parentheses are not supported in a context with let \ + chains", + ); + } + } + diag.emit(); + } else { + sess.struct_span_err(expr.span, "expected expression, found statement (`let`)") + .note("variable declaration using `let` is a statement") + .emit(); + } + } + + fn check_gat_where( + &mut self, + id: NodeId, + before_predicates: &[WherePredicate], + where_clauses: (ast::TyAliasWhereClause, ast::TyAliasWhereClause), + ) { + if !before_predicates.is_empty() { + let mut state = State::new(); + if !where_clauses.1.0 { + state.space(); + state.word_space("where"); + } else { + state.word_space(","); + } + let mut first = true; + for p in before_predicates.iter() { + if !first { + state.word_space(","); + } + first = false; + state.print_where_predicate(p); + } + let suggestion = state.s.eof(); + self.lint_buffer.buffer_lint_with_diagnostic( + DEPRECATED_WHERE_CLAUSE_LOCATION, + id, + where_clauses.0.1, + "where clause not allowed here", + BuiltinLintDiagnostics::DeprecatedWhereclauseLocation( + where_clauses.1.1.shrink_to_hi(), + suggestion, + ), + ); + } + } + + fn with_banned_assoc_ty_bound(&mut self, f: impl FnOnce(&mut Self)) { + let old = mem::replace(&mut self.is_assoc_ty_bound_banned, true); + f(self); + self.is_assoc_ty_bound_banned = old; + } + + fn with_impl_trait(&mut self, outer: Option<Span>, f: impl FnOnce(&mut Self)) { + let old = mem::replace(&mut self.outer_impl_trait, outer); + if outer.is_some() { + self.with_banned_tilde_const(f); + } else { + f(self); + } + self.outer_impl_trait = old; + } + + fn visit_assoc_constraint_from_generic_args(&mut self, constraint: &'a AssocConstraint) { + match constraint.kind { + AssocConstraintKind::Equality { .. } => {} + AssocConstraintKind::Bound { .. } => { + if self.is_assoc_ty_bound_banned { + self.err_handler().span_err( + constraint.span, + "associated type bounds are not allowed within structs, enums, or unions", + ); + } + } + } + self.visit_assoc_constraint(constraint); + } + + // Mirrors `visit::walk_ty`, but tracks relevant state. + fn walk_ty(&mut self, t: &'a Ty) { + match t.kind { + TyKind::ImplTrait(..) => { + self.with_impl_trait(Some(t.span), |this| visit::walk_ty(this, t)) + } + TyKind::TraitObject(..) => self.with_banned_tilde_const(|this| visit::walk_ty(this, t)), + TyKind::Path(ref qself, ref path) => { + // We allow these: + // - `Option<impl Trait>` + // - `option::Option<impl Trait>` + // - `option::Option<T>::Foo<impl Trait> + // + // But not these: + // - `<impl Trait>::Foo` + // - `option::Option<impl Trait>::Foo`. + // + // To implement this, we disallow `impl Trait` from `qself` + // (for cases like `<impl Trait>::Foo>`) + // but we allow `impl Trait` in `GenericArgs` + // iff there are no more PathSegments. + if let Some(ref qself) = *qself { + // `impl Trait` in `qself` is always illegal + self.with_banned_impl_trait(|this| this.visit_ty(&qself.ty)); + } + + // Note that there should be a call to visit_path here, + // so if any logic is added to process `Path`s a call to it should be + // added both in visit_path and here. This code mirrors visit::walk_path. + for (i, segment) in path.segments.iter().enumerate() { + // Allow `impl Trait` iff we're on the final path segment + if i == path.segments.len() - 1 { + self.visit_path_segment(path.span, segment); + } else { + self.with_banned_impl_trait(|this| { + this.visit_path_segment(path.span, segment) + }); + } + } + } + _ => visit::walk_ty(self, t), + } + } + + fn visit_struct_field_def(&mut self, field: &'a FieldDef) { + if let Some(ident) = field.ident { + if ident.name == kw::Underscore { + self.visit_vis(&field.vis); + self.visit_ident(ident); + self.visit_ty_common(&field.ty); + self.walk_ty(&field.ty); + walk_list!(self, visit_attribute, &field.attrs); + return; + } + } + self.visit_field_def(field); + } + + fn err_handler(&self) -> &rustc_errors::Handler { + &self.session.diagnostic() + } + + fn check_lifetime(&self, ident: Ident) { + let valid_names = [kw::UnderscoreLifetime, kw::StaticLifetime, kw::Empty]; + if !valid_names.contains(&ident.name) && ident.without_first_quote().is_reserved() { + self.err_handler().span_err(ident.span, "lifetimes cannot use keyword names"); + } + } + + fn check_label(&self, ident: Ident) { + if ident.without_first_quote().is_reserved() { + self.err_handler() + .span_err(ident.span, &format!("invalid label name `{}`", ident.name)); + } + } + + fn invalid_visibility(&self, vis: &Visibility, note: Option<&str>) { + if let VisibilityKind::Inherited = vis.kind { + return; + } + + let mut err = + struct_span_err!(self.session, vis.span, E0449, "unnecessary visibility qualifier"); + if vis.kind.is_pub() { + err.span_label(vis.span, "`pub` not permitted here because it's implied"); + } + if let Some(note) = note { + err.note(note); + } + err.emit(); + } + + fn check_decl_no_pat(decl: &FnDecl, mut report_err: impl FnMut(Span, Option<Ident>, bool)) { + for Param { pat, .. } in &decl.inputs { + match pat.kind { + PatKind::Ident(BindingMode::ByValue(Mutability::Not), _, None) | PatKind::Wild => {} + PatKind::Ident(BindingMode::ByValue(Mutability::Mut), ident, None) => { + report_err(pat.span, Some(ident), true) + } + _ => report_err(pat.span, None, false), + } + } + } + + fn check_trait_fn_not_async(&self, fn_span: Span, asyncness: Async) { + if let Async::Yes { span, .. } = asyncness { + struct_span_err!( + self.session, + fn_span, + E0706, + "functions in traits cannot be declared `async`" + ) + .span_label(span, "`async` because of this") + .note("`async` trait functions are not currently supported") + .note("consider using the `async-trait` crate: https://crates.io/crates/async-trait") + .emit(); + } + } + + fn check_trait_fn_not_const(&self, constness: Const) { + if let Const::Yes(span) = constness { + struct_span_err!( + self.session, + span, + E0379, + "functions in traits cannot be declared const" + ) + .span_label(span, "functions in traits cannot be const") + .emit(); + } + } + + fn check_late_bound_lifetime_defs(&self, params: &[GenericParam]) { + // Check only lifetime parameters are present and that the lifetime + // parameters that are present have no bounds. + let non_lt_param_spans: Vec<_> = params + .iter() + .filter_map(|param| match param.kind { + GenericParamKind::Lifetime { .. } => { + if !param.bounds.is_empty() { + let spans: Vec<_> = param.bounds.iter().map(|b| b.span()).collect(); + self.err_handler() + .span_err(spans, "lifetime bounds cannot be used in this context"); + } + None + } + _ => Some(param.ident.span), + }) + .collect(); + if !non_lt_param_spans.is_empty() { + self.err_handler().span_err( + non_lt_param_spans, + "only lifetime parameters can be used in this context", + ); + } + } + + fn check_fn_decl(&self, fn_decl: &FnDecl, self_semantic: SelfSemantic) { + self.check_decl_num_args(fn_decl); + self.check_decl_cvaradic_pos(fn_decl); + self.check_decl_attrs(fn_decl); + self.check_decl_self_param(fn_decl, self_semantic); + } + + /// Emits fatal error if function declaration has more than `u16::MAX` arguments + /// Error is fatal to prevent errors during typechecking + fn check_decl_num_args(&self, fn_decl: &FnDecl) { + let max_num_args: usize = u16::MAX.into(); + if fn_decl.inputs.len() > max_num_args { + let Param { span, .. } = fn_decl.inputs[0]; + self.err_handler().span_fatal( + span, + &format!("function can not have more than {} arguments", max_num_args), + ); + } + } + + fn check_decl_cvaradic_pos(&self, fn_decl: &FnDecl) { + match &*fn_decl.inputs { + [Param { ty, span, .. }] => { + if let TyKind::CVarArgs = ty.kind { + self.err_handler().span_err( + *span, + "C-variadic function must be declared with at least one named argument", + ); + } + } + [ps @ .., _] => { + for Param { ty, span, .. } in ps { + if let TyKind::CVarArgs = ty.kind { + self.err_handler().span_err( + *span, + "`...` must be the last argument of a C-variadic function", + ); + } + } + } + _ => {} + } + } + + fn check_decl_attrs(&self, fn_decl: &FnDecl) { + fn_decl + .inputs + .iter() + .flat_map(|i| i.attrs.as_ref()) + .filter(|attr| { + let arr = [ + sym::allow, + sym::cfg, + sym::cfg_attr, + sym::deny, + sym::expect, + sym::forbid, + sym::warn, + ]; + !arr.contains(&attr.name_or_empty()) && rustc_attr::is_builtin_attr(attr) + }) + .for_each(|attr| { + if attr.is_doc_comment() { + self.err_handler() + .struct_span_err( + attr.span, + "documentation comments cannot be applied to function parameters", + ) + .span_label(attr.span, "doc comments are not allowed here") + .emit(); + } else { + self.err_handler().span_err( + attr.span, + "allow, cfg, cfg_attr, deny, expect, \ + forbid, and warn are the only allowed built-in attributes in function parameters", + ); + } + }); + } + + fn check_decl_self_param(&self, fn_decl: &FnDecl, self_semantic: SelfSemantic) { + if let (SelfSemantic::No, [param, ..]) = (self_semantic, &*fn_decl.inputs) { + if param.is_self() { + self.err_handler() + .struct_span_err( + param.span, + "`self` parameter is only allowed in associated functions", + ) + .span_label(param.span, "not semantically valid as function parameter") + .note("associated functions are those in `impl` or `trait` definitions") + .emit(); + } + } + } + + fn check_defaultness(&self, span: Span, defaultness: Defaultness) { + if let Defaultness::Default(def_span) = defaultness { + let span = self.session.source_map().guess_head_span(span); + self.err_handler() + .struct_span_err(span, "`default` is only allowed on items in trait impls") + .span_label(def_span, "`default` because of this") + .emit(); + } + } + + fn error_item_without_body(&self, sp: Span, ctx: &str, msg: &str, sugg: &str) { + self.error_item_without_body_with_help(sp, ctx, msg, sugg, |_| ()); + } + + fn error_item_without_body_with_help( + &self, + sp: Span, + ctx: &str, + msg: &str, + sugg: &str, + help: impl FnOnce(&mut DiagnosticBuilder<'_, ErrorGuaranteed>), + ) { + let source_map = self.session.source_map(); + let end = source_map.end_point(sp); + let replace_span = if source_map.span_to_snippet(end).map(|s| s == ";").unwrap_or(false) { + end + } else { + sp.shrink_to_hi() + }; + let mut err = self.err_handler().struct_span_err(sp, msg); + err.span_suggestion( + replace_span, + &format!("provide a definition for the {}", ctx), + sugg, + Applicability::HasPlaceholders, + ); + help(&mut err); + err.emit(); + } + + fn check_impl_item_provided<T>(&self, sp: Span, body: &Option<T>, ctx: &str, sugg: &str) { + if body.is_none() { + let msg = format!("associated {} in `impl` without body", ctx); + self.error_item_without_body(sp, ctx, &msg, sugg); + } + } + + fn check_type_no_bounds(&self, bounds: &[GenericBound], ctx: &str) { + let span = match bounds { + [] => return, + [b0] => b0.span(), + [b0, .., bl] => b0.span().to(bl.span()), + }; + self.err_handler() + .struct_span_err(span, &format!("bounds on `type`s in {} have no effect", ctx)) + .emit(); + } + + fn check_foreign_ty_genericless(&self, generics: &Generics, where_span: Span) { + let cannot_have = |span, descr, remove_descr| { + self.err_handler() + .struct_span_err( + span, + &format!("`type`s inside `extern` blocks cannot have {}", descr), + ) + .span_suggestion( + span, + &format!("remove the {}", remove_descr), + "", + Applicability::MaybeIncorrect, + ) + .span_label(self.current_extern_span(), "`extern` block begins here") + .note(MORE_EXTERN) + .emit(); + }; + + if !generics.params.is_empty() { + cannot_have(generics.span, "generic parameters", "generic parameters"); + } + + if !generics.where_clause.predicates.is_empty() { + cannot_have(where_span, "`where` clauses", "`where` clause"); + } + } + + fn check_foreign_kind_bodyless(&self, ident: Ident, kind: &str, body: Option<Span>) { + let Some(body) = body else { + return; + }; + self.err_handler() + .struct_span_err(ident.span, &format!("incorrect `{}` inside `extern` block", kind)) + .span_label(ident.span, "cannot have a body") + .span_label(body, "the invalid body") + .span_label( + self.current_extern_span(), + format!( + "`extern` blocks define existing foreign {0}s and {0}s \ + inside of them cannot have a body", + kind + ), + ) + .note(MORE_EXTERN) + .emit(); + } + + /// An `fn` in `extern { ... }` cannot have a body `{ ... }`. + fn check_foreign_fn_bodyless(&self, ident: Ident, body: Option<&Block>) { + let Some(body) = body else { + return; + }; + self.err_handler() + .struct_span_err(ident.span, "incorrect function inside `extern` block") + .span_label(ident.span, "cannot have a body") + .span_suggestion( + body.span, + "remove the invalid body", + ";", + Applicability::MaybeIncorrect, + ) + .help( + "you might have meant to write a function accessible through FFI, \ + which can be done by writing `extern fn` outside of the `extern` block", + ) + .span_label( + self.current_extern_span(), + "`extern` blocks define existing foreign functions and functions \ + inside of them cannot have a body", + ) + .note(MORE_EXTERN) + .emit(); + } + + fn current_extern_span(&self) -> Span { + self.session.source_map().guess_head_span(self.extern_mod.unwrap().span) + } + + /// An `fn` in `extern { ... }` cannot have qualifiers, e.g. `async fn`. + fn check_foreign_fn_headerless(&self, ident: Ident, span: Span, header: FnHeader) { + if header.has_qualifiers() { + self.err_handler() + .struct_span_err(ident.span, "functions in `extern` blocks cannot have qualifiers") + .span_label(self.current_extern_span(), "in this `extern` block") + .span_suggestion_verbose( + span.until(ident.span.shrink_to_lo()), + "remove the qualifiers", + "fn ", + Applicability::MaybeIncorrect, + ) + .emit(); + } + } + + /// An item in `extern { ... }` cannot use non-ascii identifier. + fn check_foreign_item_ascii_only(&self, ident: Ident) { + if !ident.as_str().is_ascii() { + let n = 83942; + self.err_handler() + .struct_span_err( + ident.span, + "items in `extern` blocks cannot use non-ascii identifiers", + ) + .span_label(self.current_extern_span(), "in this `extern` block") + .note(&format!( + "this limitation may be lifted in the future; see issue #{} <https://github.com/rust-lang/rust/issues/{}> for more information", + n, n, + )) + .emit(); + } + } + + /// Reject C-variadic type unless the function is foreign, + /// or free and `unsafe extern "C"` semantically. + fn check_c_variadic_type(&self, fk: FnKind<'a>) { + match (fk.ctxt(), fk.header()) { + (Some(FnCtxt::Foreign), _) => return, + (Some(FnCtxt::Free), Some(header)) => match header.ext { + Extern::Explicit(StrLit { symbol_unescaped: sym::C, .. }, _) + | Extern::Implicit(_) + if matches!(header.unsafety, Unsafe::Yes(_)) => + { + return; + } + _ => {} + }, + _ => {} + }; + + for Param { ty, span, .. } in &fk.decl().inputs { + if let TyKind::CVarArgs = ty.kind { + self.err_handler() + .struct_span_err( + *span, + "only foreign or `unsafe extern \"C\"` functions may be C-variadic", + ) + .emit(); + } + } + } + + fn check_item_named(&self, ident: Ident, kind: &str) { + if ident.name != kw::Underscore { + return; + } + self.err_handler() + .struct_span_err(ident.span, &format!("`{}` items in this context need a name", kind)) + .span_label(ident.span, format!("`_` is not a valid name for this `{}` item", kind)) + .emit(); + } + + fn check_nomangle_item_asciionly(&self, ident: Ident, item_span: Span) { + if ident.name.as_str().is_ascii() { + return; + } + let head_span = self.session.source_map().guess_head_span(item_span); + struct_span_err!( + self.session, + head_span, + E0754, + "`#[no_mangle]` requires ASCII identifier" + ) + .emit(); + } + + fn check_mod_file_item_asciionly(&self, ident: Ident) { + if ident.name.as_str().is_ascii() { + return; + } + struct_span_err!( + self.session, + ident.span, + E0754, + "trying to load file for module `{}` with non-ascii identifier name", + ident.name + ) + .help("consider using `#[path]` attribute to specify filesystem path") + .emit(); + } + + fn deny_generic_params(&self, generics: &Generics, ident_span: Span) { + if !generics.params.is_empty() { + struct_span_err!( + self.session, + generics.span, + E0567, + "auto traits cannot have generic parameters" + ) + .span_label(ident_span, "auto trait cannot have generic parameters") + .span_suggestion( + generics.span, + "remove the parameters", + "", + Applicability::MachineApplicable, + ) + .emit(); + } + } + + fn emit_e0568(&self, span: Span, ident_span: Span) { + struct_span_err!( + self.session, + span, + E0568, + "auto traits cannot have super traits or lifetime bounds" + ) + .span_label(ident_span, "auto trait cannot have super traits or lifetime bounds") + .span_suggestion( + span, + "remove the super traits or lifetime bounds", + "", + Applicability::MachineApplicable, + ) + .emit(); + } + + fn deny_super_traits(&self, bounds: &GenericBounds, ident_span: Span) { + if let [.., last] = &bounds[..] { + let span = ident_span.shrink_to_hi().to(last.span()); + self.emit_e0568(span, ident_span); + } + } + + fn deny_where_clause(&self, where_clause: &WhereClause, ident_span: Span) { + if !where_clause.predicates.is_empty() { + self.emit_e0568(where_clause.span, ident_span); + } + } + + fn deny_items(&self, trait_items: &[P<AssocItem>], ident_span: Span) { + if !trait_items.is_empty() { + let spans: Vec<_> = trait_items.iter().map(|i| i.ident.span).collect(); + let total_span = trait_items.first().unwrap().span.to(trait_items.last().unwrap().span); + struct_span_err!( + self.session, + spans, + E0380, + "auto traits cannot have associated items" + ) + .span_suggestion( + total_span, + "remove these associated items", + "", + Applicability::MachineApplicable, + ) + .span_label(ident_span, "auto trait cannot have associated items") + .emit(); + } + } + + fn correct_generic_order_suggestion(&self, data: &AngleBracketedArgs) -> String { + // Lifetimes always come first. + let lt_sugg = data.args.iter().filter_map(|arg| match arg { + AngleBracketedArg::Arg(lt @ GenericArg::Lifetime(_)) => { + Some(pprust::to_string(|s| s.print_generic_arg(lt))) + } + _ => None, + }); + let args_sugg = data.args.iter().filter_map(|a| match a { + AngleBracketedArg::Arg(GenericArg::Lifetime(_)) | AngleBracketedArg::Constraint(_) => { + None + } + AngleBracketedArg::Arg(arg) => Some(pprust::to_string(|s| s.print_generic_arg(arg))), + }); + // Constraints always come last. + let constraint_sugg = data.args.iter().filter_map(|a| match a { + AngleBracketedArg::Arg(_) => None, + AngleBracketedArg::Constraint(c) => { + Some(pprust::to_string(|s| s.print_assoc_constraint(c))) + } + }); + format!( + "<{}>", + lt_sugg.chain(args_sugg).chain(constraint_sugg).collect::<Vec<String>>().join(", ") + ) + } + + /// Enforce generic args coming before constraints in `<...>` of a path segment. + fn check_generic_args_before_constraints(&self, data: &AngleBracketedArgs) { + // Early exit in case it's partitioned as it should be. + if data.args.iter().is_partitioned(|arg| matches!(arg, AngleBracketedArg::Arg(_))) { + return; + } + // Find all generic argument coming after the first constraint... + let (constraint_spans, arg_spans): (Vec<Span>, Vec<Span>) = + data.args.iter().partition_map(|arg| match arg { + AngleBracketedArg::Constraint(c) => Either::Left(c.span), + AngleBracketedArg::Arg(a) => Either::Right(a.span()), + }); + let args_len = arg_spans.len(); + let constraint_len = constraint_spans.len(); + // ...and then error: + self.err_handler() + .struct_span_err( + arg_spans.clone(), + "generic arguments must come before the first constraint", + ) + .span_label(constraint_spans[0], &format!("constraint{}", pluralize!(constraint_len))) + .span_label( + *arg_spans.iter().last().unwrap(), + &format!("generic argument{}", pluralize!(args_len)), + ) + .span_labels(constraint_spans, "") + .span_labels(arg_spans, "") + .span_suggestion_verbose( + data.span, + &format!( + "move the constraint{} after the generic argument{}", + pluralize!(constraint_len), + pluralize!(args_len) + ), + self.correct_generic_order_suggestion(&data), + Applicability::MachineApplicable, + ) + .emit(); + } + + fn visit_ty_common(&mut self, ty: &'a Ty) { + match ty.kind { + TyKind::BareFn(ref bfty) => { + self.check_fn_decl(&bfty.decl, SelfSemantic::No); + Self::check_decl_no_pat(&bfty.decl, |span, _, _| { + struct_span_err!( + self.session, + span, + E0561, + "patterns aren't allowed in function pointer types" + ) + .emit(); + }); + self.check_late_bound_lifetime_defs(&bfty.generic_params); + if let Extern::Implicit(_) = bfty.ext { + let sig_span = self.session.source_map().next_point(ty.span.shrink_to_lo()); + self.maybe_lint_missing_abi(sig_span, ty.id); + } + } + TyKind::TraitObject(ref bounds, ..) => { + let mut any_lifetime_bounds = false; + for bound in bounds { + if let GenericBound::Outlives(ref lifetime) = *bound { + if any_lifetime_bounds { + struct_span_err!( + self.session, + lifetime.ident.span, + E0226, + "only a single explicit lifetime bound is permitted" + ) + .emit(); + break; + } + any_lifetime_bounds = true; + } + } + } + TyKind::ImplTrait(_, ref bounds) => { + if self.is_impl_trait_banned { + struct_span_err!( + self.session, + ty.span, + E0667, + "`impl Trait` is not allowed in path parameters" + ) + .emit(); + } + + if let Some(outer_impl_trait_sp) = self.outer_impl_trait { + struct_span_err!( + self.session, + ty.span, + E0666, + "nested `impl Trait` is not allowed" + ) + .span_label(outer_impl_trait_sp, "outer `impl Trait`") + .span_label(ty.span, "nested `impl Trait` here") + .emit(); + } + + if !bounds.iter().any(|b| matches!(b, GenericBound::Trait(..))) { + self.err_handler().span_err(ty.span, "at least one trait must be specified"); + } + } + _ => {} + } + } + + fn maybe_lint_missing_abi(&mut self, span: Span, id: NodeId) { + // FIXME(davidtwco): This is a hack to detect macros which produce spans of the + // call site which do not have a macro backtrace. See #61963. + let is_macro_callsite = self + .session + .source_map() + .span_to_snippet(span) + .map(|snippet| snippet.starts_with("#[")) + .unwrap_or(true); + if !is_macro_callsite { + self.lint_buffer.buffer_lint_with_diagnostic( + MISSING_ABI, + id, + span, + "extern declarations without an explicit ABI are deprecated", + BuiltinLintDiagnostics::MissingAbi(span, abi::Abi::FALLBACK), + ) + } + } +} + +/// Checks that generic parameters are in the correct order, +/// which is lifetimes, then types and then consts. (`<'a, T, const N: usize>`) +fn validate_generic_param_order( + handler: &rustc_errors::Handler, + generics: &[GenericParam], + span: Span, +) { + let mut max_param: Option<ParamKindOrd> = None; + let mut out_of_order = FxHashMap::default(); + let mut param_idents = Vec::with_capacity(generics.len()); + + for (idx, param) in generics.iter().enumerate() { + let ident = param.ident; + let (kind, bounds, span) = (¶m.kind, ¶m.bounds, ident.span); + let (ord_kind, ident) = match ¶m.kind { + GenericParamKind::Lifetime => (ParamKindOrd::Lifetime, ident.to_string()), + GenericParamKind::Type { default: _ } => (ParamKindOrd::Type, ident.to_string()), + GenericParamKind::Const { ref ty, kw_span: _, default: _ } => { + let ty = pprust::ty_to_string(ty); + (ParamKindOrd::Const, format!("const {}: {}", ident, ty)) + } + }; + param_idents.push((kind, ord_kind, bounds, idx, ident)); + match max_param { + Some(max_param) if max_param > ord_kind => { + let entry = out_of_order.entry(ord_kind).or_insert((max_param, vec![])); + entry.1.push(span); + } + Some(_) | None => max_param = Some(ord_kind), + }; + } + + if !out_of_order.is_empty() { + let mut ordered_params = "<".to_string(); + param_idents.sort_by_key(|&(_, po, _, i, _)| (po, i)); + let mut first = true; + for (kind, _, bounds, _, ident) in param_idents { + if !first { + ordered_params += ", "; + } + ordered_params += &ident; + + if !bounds.is_empty() { + ordered_params += ": "; + ordered_params += &pprust::bounds_to_string(&bounds); + } + + match kind { + GenericParamKind::Type { default: Some(default) } => { + ordered_params += " = "; + ordered_params += &pprust::ty_to_string(default); + } + GenericParamKind::Type { default: None } => (), + GenericParamKind::Lifetime => (), + GenericParamKind::Const { ty: _, kw_span: _, default: Some(default) } => { + ordered_params += " = "; + ordered_params += &pprust::expr_to_string(&*default.value); + } + GenericParamKind::Const { ty: _, kw_span: _, default: None } => (), + } + first = false; + } + + ordered_params += ">"; + + for (param_ord, (max_param, spans)) in &out_of_order { + let mut err = handler.struct_span_err( + spans.clone(), + &format!( + "{} parameters must be declared prior to {} parameters", + param_ord, max_param, + ), + ); + err.span_suggestion( + span, + "reorder the parameters: lifetimes, then consts and types", + &ordered_params, + Applicability::MachineApplicable, + ); + err.emit(); + } + } +} + +impl<'a> Visitor<'a> for AstValidator<'a> { + fn visit_attribute(&mut self, attr: &Attribute) { + validate_attr::check_meta(&self.session.parse_sess, attr); + } + + fn visit_expr(&mut self, expr: &'a Expr) { + self.with_let_management(Some(ForbiddenLetReason::GenericForbidden), |this, forbidden_let_reason| { + match &expr.kind { + ExprKind::Binary(Spanned { node: BinOpKind::Or, span }, lhs, rhs) => { + let local_reason = Some(ForbiddenLetReason::NotSupportedOr(*span)); + this.with_let_management(local_reason, |this, _| this.visit_expr(lhs)); + this.with_let_management(local_reason, |this, _| this.visit_expr(rhs)); + } + ExprKind::If(cond, then, opt_else) => { + this.visit_block(then); + walk_list!(this, visit_expr, opt_else); + this.with_let_management(None, |this, _| this.visit_expr(cond)); + return; + } + ExprKind::Let(..) if let Some(elem) = forbidden_let_reason => { + this.ban_let_expr(expr, elem); + }, + ExprKind::Match(scrutinee, arms) => { + this.visit_expr(scrutinee); + for arm in arms { + this.visit_expr(&arm.body); + this.visit_pat(&arm.pat); + walk_list!(this, visit_attribute, &arm.attrs); + if let Some(guard) = &arm.guard && let ExprKind::Let(_, guard_expr, _) = &guard.kind { + this.with_let_management(None, |this, _| { + this.visit_expr(guard_expr) + }); + return; + } + } + } + ExprKind::Paren(local_expr) => { + fn has_let_expr(expr: &Expr) -> bool { + match expr.kind { + ExprKind::Binary(_, ref lhs, ref rhs) => has_let_expr(lhs) || has_let_expr(rhs), + ExprKind::Let(..) => true, + _ => false, + } + } + let local_reason = if has_let_expr(local_expr) { + Some(ForbiddenLetReason::NotSupportedParentheses(local_expr.span)) + } + else { + forbidden_let_reason + }; + this.with_let_management(local_reason, |this, _| this.visit_expr(local_expr)); + } + ExprKind::Binary(Spanned { node: BinOpKind::And, .. }, ..) => { + this.with_let_management(forbidden_let_reason, |this, _| visit::walk_expr(this, expr)); + return; + } + ExprKind::While(cond, then, opt_label) => { + walk_list!(this, visit_label, opt_label); + this.visit_block(then); + this.with_let_management(None, |this, _| this.visit_expr(cond)); + return; + } + _ => visit::walk_expr(this, expr), + } + }); + } + + fn visit_ty(&mut self, ty: &'a Ty) { + self.visit_ty_common(ty); + self.walk_ty(ty) + } + + fn visit_label(&mut self, label: &'a Label) { + self.check_label(label.ident); + visit::walk_label(self, label); + } + + fn visit_lifetime(&mut self, lifetime: &'a Lifetime, _: visit::LifetimeCtxt) { + self.check_lifetime(lifetime.ident); + visit::walk_lifetime(self, lifetime); + } + + fn visit_field_def(&mut self, s: &'a FieldDef) { + visit::walk_field_def(self, s) + } + + fn visit_item(&mut self, item: &'a Item) { + if item.attrs.iter().any(|attr| self.session.is_proc_macro_attr(attr)) { + self.has_proc_macro_decls = true; + } + + if self.session.contains_name(&item.attrs, sym::no_mangle) { + self.check_nomangle_item_asciionly(item.ident, item.span); + } + + match item.kind { + ItemKind::Impl(box Impl { + unsafety, + polarity, + defaultness: _, + constness, + ref generics, + of_trait: Some(ref t), + ref self_ty, + ref items, + }) => { + self.with_in_trait_impl(true, Some(constness), |this| { + this.invalid_visibility(&item.vis, None); + if let TyKind::Err = self_ty.kind { + this.err_handler() + .struct_span_err( + item.span, + "`impl Trait for .. {}` is an obsolete syntax", + ) + .help("use `auto trait Trait {}` instead") + .emit(); + } + if let (Unsafe::Yes(span), ImplPolarity::Negative(sp)) = (unsafety, polarity) { + struct_span_err!( + this.session, + sp.to(t.path.span), + E0198, + "negative impls cannot be unsafe" + ) + .span_label(sp, "negative because of this") + .span_label(span, "unsafe because of this") + .emit(); + } + + this.visit_vis(&item.vis); + this.visit_ident(item.ident); + if let Const::Yes(_) = constness { + this.with_tilde_const_allowed(|this| this.visit_generics(generics)); + } else { + this.visit_generics(generics); + } + this.visit_trait_ref(t); + this.visit_ty(self_ty); + + walk_list!(this, visit_assoc_item, items, AssocCtxt::Impl); + }); + return; // Avoid visiting again. + } + ItemKind::Impl(box Impl { + unsafety, + polarity, + defaultness, + constness, + generics: _, + of_trait: None, + ref self_ty, + items: _, + }) => { + let error = |annotation_span, annotation| { + let mut err = self.err_handler().struct_span_err( + self_ty.span, + &format!("inherent impls cannot be {}", annotation), + ); + err.span_label(annotation_span, &format!("{} because of this", annotation)); + err.span_label(self_ty.span, "inherent impl for this type"); + err + }; + + self.invalid_visibility( + &item.vis, + Some("place qualifiers on individual impl items instead"), + ); + if let Unsafe::Yes(span) = unsafety { + error(span, "unsafe").code(error_code!(E0197)).emit(); + } + if let ImplPolarity::Negative(span) = polarity { + error(span, "negative").emit(); + } + if let Defaultness::Default(def_span) = defaultness { + error(def_span, "`default`") + .note("only trait implementations may be annotated with `default`") + .emit(); + } + if let Const::Yes(span) = constness { + error(span, "`const`") + .note("only trait implementations may be annotated with `const`") + .emit(); + } + } + ItemKind::Fn(box Fn { defaultness, ref sig, ref generics, ref body }) => { + self.check_defaultness(item.span, defaultness); + + if body.is_none() { + let msg = "free function without a body"; + let ext = sig.header.ext; + + let f = |e: &mut DiagnosticBuilder<'_, _>| { + if let Extern::Implicit(start_span) | Extern::Explicit(_, start_span) = &ext + { + let start_suggestion = if let Extern::Explicit(abi, _) = ext { + format!("extern \"{}\" {{", abi.symbol_unescaped) + } else { + "extern {".to_owned() + }; + + let end_suggestion = " }".to_owned(); + let end_span = item.span.shrink_to_hi(); + + e + .multipart_suggestion( + "if you meant to declare an externally defined function, use an `extern` block", + vec![(*start_span, start_suggestion), (end_span, end_suggestion)], + Applicability::MaybeIncorrect, + ); + } + }; + + self.error_item_without_body_with_help( + item.span, + "function", + msg, + " { <body> }", + f, + ); + } + + self.visit_vis(&item.vis); + self.visit_ident(item.ident); + let kind = + FnKind::Fn(FnCtxt::Free, item.ident, sig, &item.vis, generics, body.as_deref()); + self.visit_fn(kind, item.span, item.id); + walk_list!(self, visit_attribute, &item.attrs); + return; // Avoid visiting again. + } + ItemKind::ForeignMod(ForeignMod { abi, unsafety, .. }) => { + let old_item = mem::replace(&mut self.extern_mod, Some(item)); + self.invalid_visibility( + &item.vis, + Some("place qualifiers on individual foreign items instead"), + ); + if let Unsafe::Yes(span) = unsafety { + self.err_handler().span_err(span, "extern block cannot be declared unsafe"); + } + if abi.is_none() { + self.maybe_lint_missing_abi(item.span, item.id); + } + visit::walk_item(self, item); + self.extern_mod = old_item; + return; // Avoid visiting again. + } + ItemKind::Enum(ref def, _) => { + for variant in &def.variants { + self.invalid_visibility(&variant.vis, None); + for field in variant.data.fields() { + self.invalid_visibility(&field.vis, None); + } + } + } + ItemKind::Trait(box Trait { is_auto, ref generics, ref bounds, ref items, .. }) => { + if is_auto == IsAuto::Yes { + // Auto traits cannot have generics, super traits nor contain items. + self.deny_generic_params(generics, item.ident.span); + self.deny_super_traits(bounds, item.ident.span); + self.deny_where_clause(&generics.where_clause, item.ident.span); + self.deny_items(items, item.ident.span); + } + + // Equivalent of `visit::walk_item` for `ItemKind::Trait` that inserts a bound + // context for the supertraits. + self.visit_vis(&item.vis); + self.visit_ident(item.ident); + self.visit_generics(generics); + self.with_tilde_const_allowed(|this| { + walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits) + }); + walk_list!(self, visit_assoc_item, items, AssocCtxt::Trait); + walk_list!(self, visit_attribute, &item.attrs); + return; + } + ItemKind::Mod(unsafety, ref mod_kind) => { + if let Unsafe::Yes(span) = unsafety { + self.err_handler().span_err(span, "module cannot be declared unsafe"); + } + // Ensure that `path` attributes on modules are recorded as used (cf. issue #35584). + if !matches!(mod_kind, ModKind::Loaded(_, Inline::Yes, _)) + && !self.session.contains_name(&item.attrs, sym::path) + { + self.check_mod_file_item_asciionly(item.ident); + } + } + ItemKind::Struct(ref vdata, ref generics) => match vdata { + // Duplicating the `Visitor` logic allows catching all cases + // of `Anonymous(Struct, Union)` outside of a field struct or union. + // + // Inside `visit_ty` the validator catches every `Anonymous(Struct, Union)` it + // encounters, and only on `ItemKind::Struct` and `ItemKind::Union` + // it uses `visit_ty_common`, which doesn't contain that specific check. + VariantData::Struct(ref fields, ..) => { + self.visit_vis(&item.vis); + self.visit_ident(item.ident); + self.visit_generics(generics); + self.with_banned_assoc_ty_bound(|this| { + walk_list!(this, visit_struct_field_def, fields); + }); + walk_list!(self, visit_attribute, &item.attrs); + return; + } + _ => {} + }, + ItemKind::Union(ref vdata, ref generics) => { + if vdata.fields().is_empty() { + self.err_handler().span_err(item.span, "unions cannot have zero fields"); + } + match vdata { + VariantData::Struct(ref fields, ..) => { + self.visit_vis(&item.vis); + self.visit_ident(item.ident); + self.visit_generics(generics); + self.with_banned_assoc_ty_bound(|this| { + walk_list!(this, visit_struct_field_def, fields); + }); + walk_list!(self, visit_attribute, &item.attrs); + return; + } + _ => {} + } + } + ItemKind::Const(def, .., None) => { + self.check_defaultness(item.span, def); + let msg = "free constant item without body"; + self.error_item_without_body(item.span, "constant", msg, " = <expr>;"); + } + ItemKind::Static(.., None) => { + let msg = "free static item without body"; + self.error_item_without_body(item.span, "static", msg, " = <expr>;"); + } + ItemKind::TyAlias(box TyAlias { + defaultness, + where_clauses, + ref bounds, + ref ty, + .. + }) => { + self.check_defaultness(item.span, defaultness); + if ty.is_none() { + let msg = "free type alias without body"; + self.error_item_without_body(item.span, "type", msg, " = <type>;"); + } + self.check_type_no_bounds(bounds, "this context"); + if where_clauses.1.0 { + let mut err = self.err_handler().struct_span_err( + where_clauses.1.1, + "where clauses are not allowed after the type for type aliases", + ); + err.note( + "see issue #89122 <https://github.com/rust-lang/rust/issues/89122> for more information", + ); + err.emit(); + } + } + _ => {} + } + + visit::walk_item(self, item); + } + + fn visit_foreign_item(&mut self, fi: &'a ForeignItem) { + match &fi.kind { + ForeignItemKind::Fn(box Fn { defaultness, sig, body, .. }) => { + self.check_defaultness(fi.span, *defaultness); + self.check_foreign_fn_bodyless(fi.ident, body.as_deref()); + self.check_foreign_fn_headerless(fi.ident, fi.span, sig.header); + self.check_foreign_item_ascii_only(fi.ident); + } + ForeignItemKind::TyAlias(box TyAlias { + defaultness, + generics, + where_clauses, + bounds, + ty, + .. + }) => { + self.check_defaultness(fi.span, *defaultness); + self.check_foreign_kind_bodyless(fi.ident, "type", ty.as_ref().map(|b| b.span)); + self.check_type_no_bounds(bounds, "`extern` blocks"); + self.check_foreign_ty_genericless(generics, where_clauses.0.1); + self.check_foreign_item_ascii_only(fi.ident); + } + ForeignItemKind::Static(_, _, body) => { + self.check_foreign_kind_bodyless(fi.ident, "static", body.as_ref().map(|b| b.span)); + self.check_foreign_item_ascii_only(fi.ident); + } + ForeignItemKind::MacCall(..) => {} + } + + visit::walk_foreign_item(self, fi) + } + + // Mirrors `visit::walk_generic_args`, but tracks relevant state. + fn visit_generic_args(&mut self, _: Span, generic_args: &'a GenericArgs) { + match *generic_args { + GenericArgs::AngleBracketed(ref data) => { + self.check_generic_args_before_constraints(data); + + for arg in &data.args { + match arg { + AngleBracketedArg::Arg(arg) => self.visit_generic_arg(arg), + // Type bindings such as `Item = impl Debug` in `Iterator<Item = Debug>` + // are allowed to contain nested `impl Trait`. + AngleBracketedArg::Constraint(constraint) => { + self.with_impl_trait(None, |this| { + this.visit_assoc_constraint_from_generic_args(constraint); + }); + } + } + } + } + GenericArgs::Parenthesized(ref data) => { + walk_list!(self, visit_ty, &data.inputs); + if let FnRetTy::Ty(ty) = &data.output { + // `-> Foo` syntax is essentially an associated type binding, + // so it is also allowed to contain nested `impl Trait`. + self.with_impl_trait(None, |this| this.visit_ty(ty)); + } + } + } + } + + fn visit_generics(&mut self, generics: &'a Generics) { + let mut prev_param_default = None; + for param in &generics.params { + match param.kind { + GenericParamKind::Lifetime => (), + GenericParamKind::Type { default: Some(_), .. } + | GenericParamKind::Const { default: Some(_), .. } => { + prev_param_default = Some(param.ident.span); + } + GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => { + if let Some(span) = prev_param_default { + let mut err = self.err_handler().struct_span_err( + span, + "generic parameters with a default must be trailing", + ); + err.emit(); + break; + } + } + } + } + + validate_generic_param_order(self.err_handler(), &generics.params, generics.span); + + for predicate in &generics.where_clause.predicates { + if let WherePredicate::EqPredicate(ref predicate) = *predicate { + deny_equality_constraints(self, predicate, generics); + } + } + walk_list!(self, visit_generic_param, &generics.params); + for predicate in &generics.where_clause.predicates { + match predicate { + WherePredicate::BoundPredicate(bound_pred) => { + // A type binding, eg `for<'c> Foo: Send+Clone+'c` + self.check_late_bound_lifetime_defs(&bound_pred.bound_generic_params); + + // This is slightly complicated. Our representation for poly-trait-refs contains a single + // binder and thus we only allow a single level of quantification. However, + // the syntax of Rust permits quantification in two places in where clauses, + // e.g., `T: for <'a> Foo<'a>` and `for <'a, 'b> &'b T: Foo<'a>`. If both are + // defined, then error. + if !bound_pred.bound_generic_params.is_empty() { + for bound in &bound_pred.bounds { + match bound { + GenericBound::Trait(t, _) => { + if !t.bound_generic_params.is_empty() { + struct_span_err!( + self.err_handler(), + t.span, + E0316, + "nested quantification of lifetimes" + ) + .emit(); + } + } + GenericBound::Outlives(_) => {} + } + } + } + } + _ => {} + } + self.visit_where_predicate(predicate); + } + } + + fn visit_generic_param(&mut self, param: &'a GenericParam) { + if let GenericParamKind::Lifetime { .. } = param.kind { + self.check_lifetime(param.ident); + } + visit::walk_generic_param(self, param); + } + + fn visit_param_bound(&mut self, bound: &'a GenericBound, ctxt: BoundKind) { + if let GenericBound::Trait(ref poly, modify) = *bound { + match (ctxt, modify) { + (BoundKind::SuperTraits, TraitBoundModifier::Maybe) => { + let mut err = self + .err_handler() + .struct_span_err(poly.span, "`?Trait` is not permitted in supertraits"); + let path_str = pprust::path_to_string(&poly.trait_ref.path); + err.note(&format!("traits are `?{}` by default", path_str)); + err.emit(); + } + (BoundKind::TraitObject, TraitBoundModifier::Maybe) => { + let mut err = self.err_handler().struct_span_err( + poly.span, + "`?Trait` is not permitted in trait object types", + ); + err.emit(); + } + (_, TraitBoundModifier::MaybeConst) => { + if !self.is_tilde_const_allowed { + self.err_handler() + .struct_span_err(bound.span(), "`~const` is not allowed here") + .note("only allowed on bounds on traits' associated types and functions, const fns, const impls and its associated functions") + .emit(); + } + } + (_, TraitBoundModifier::MaybeConstMaybe) => { + self.err_handler() + .span_err(bound.span(), "`~const` and `?` are mutually exclusive"); + } + _ => {} + } + } + + visit::walk_param_bound(self, bound) + } + + fn visit_poly_trait_ref(&mut self, t: &'a PolyTraitRef, m: &'a TraitBoundModifier) { + self.check_late_bound_lifetime_defs(&t.bound_generic_params); + visit::walk_poly_trait_ref(self, t, m); + } + + fn visit_variant_data(&mut self, s: &'a VariantData) { + self.with_banned_assoc_ty_bound(|this| visit::walk_struct_def(this, s)) + } + + fn visit_enum_def( + &mut self, + enum_definition: &'a EnumDef, + generics: &'a Generics, + item_id: NodeId, + _: Span, + ) { + self.with_banned_assoc_ty_bound(|this| { + visit::walk_enum_def(this, enum_definition, generics, item_id) + }) + } + + fn visit_fn(&mut self, fk: FnKind<'a>, span: Span, id: NodeId) { + // Only associated `fn`s can have `self` parameters. + let self_semantic = match fk.ctxt() { + Some(FnCtxt::Assoc(_)) => SelfSemantic::Yes, + _ => SelfSemantic::No, + }; + self.check_fn_decl(fk.decl(), self_semantic); + + self.check_c_variadic_type(fk); + + // Functions cannot both be `const async` + if let Some(FnHeader { + constness: Const::Yes(cspan), + asyncness: Async::Yes { span: aspan, .. }, + .. + }) = fk.header() + { + self.err_handler() + .struct_span_err( + vec![*cspan, *aspan], + "functions cannot be both `const` and `async`", + ) + .span_label(*cspan, "`const` because of this") + .span_label(*aspan, "`async` because of this") + .span_label(span, "") // Point at the fn header. + .emit(); + } + + if let FnKind::Closure(ClosureBinder::For { generic_params, .. }, ..) = fk { + self.check_late_bound_lifetime_defs(generic_params); + } + + if let FnKind::Fn( + _, + _, + FnSig { span: sig_span, header: FnHeader { ext: Extern::Implicit(_), .. }, .. }, + _, + _, + _, + ) = fk + { + self.maybe_lint_missing_abi(*sig_span, id); + } + + // Functions without bodies cannot have patterns. + if let FnKind::Fn(ctxt, _, sig, _, _, None) = fk { + Self::check_decl_no_pat(&sig.decl, |span, ident, mut_ident| { + let (code, msg, label) = match ctxt { + FnCtxt::Foreign => ( + error_code!(E0130), + "patterns aren't allowed in foreign function declarations", + "pattern not allowed in foreign function", + ), + _ => ( + error_code!(E0642), + "patterns aren't allowed in functions without bodies", + "pattern not allowed in function without body", + ), + }; + if mut_ident && matches!(ctxt, FnCtxt::Assoc(_)) { + if let Some(ident) = ident { + let diag = BuiltinLintDiagnostics::PatternsInFnsWithoutBody(span, ident); + self.lint_buffer.buffer_lint_with_diagnostic( + PATTERNS_IN_FNS_WITHOUT_BODY, + id, + span, + msg, + diag, + ) + } + } else { + self.err_handler() + .struct_span_err(span, msg) + .span_label(span, label) + .code(code) + .emit(); + } + }); + } + + let tilde_const_allowed = + matches!(fk.header(), Some(FnHeader { constness: Const::Yes(_), .. })) + || matches!(fk.ctxt(), Some(FnCtxt::Assoc(_))); + + self.with_tilde_const(tilde_const_allowed, |this| visit::walk_fn(this, fk, span)); + } + + fn visit_assoc_item(&mut self, item: &'a AssocItem, ctxt: AssocCtxt) { + if self.session.contains_name(&item.attrs, sym::no_mangle) { + self.check_nomangle_item_asciionly(item.ident, item.span); + } + + if ctxt == AssocCtxt::Trait || !self.in_trait_impl { + self.check_defaultness(item.span, item.kind.defaultness()); + } + + if ctxt == AssocCtxt::Impl { + match &item.kind { + AssocItemKind::Const(_, _, body) => { + self.check_impl_item_provided(item.span, body, "constant", " = <expr>;"); + } + AssocItemKind::Fn(box Fn { body, .. }) => { + self.check_impl_item_provided(item.span, body, "function", " { <body> }"); + } + AssocItemKind::TyAlias(box TyAlias { + generics, + where_clauses, + where_predicates_split, + bounds, + ty, + .. + }) => { + self.check_impl_item_provided(item.span, ty, "type", " = <type>;"); + self.check_type_no_bounds(bounds, "`impl`s"); + if ty.is_some() { + self.check_gat_where( + item.id, + generics.where_clause.predicates.split_at(*where_predicates_split).0, + *where_clauses, + ); + } + } + _ => {} + } + } + + if ctxt == AssocCtxt::Trait || self.in_trait_impl { + self.invalid_visibility(&item.vis, None); + if let AssocItemKind::Fn(box Fn { sig, .. }) = &item.kind { + self.check_trait_fn_not_const(sig.header.constness); + self.check_trait_fn_not_async(item.span, sig.header.asyncness); + } + } + + if let AssocItemKind::Const(..) = item.kind { + self.check_item_named(item.ident, "const"); + } + + match item.kind { + AssocItemKind::TyAlias(box TyAlias { ref generics, ref bounds, ref ty, .. }) + if ctxt == AssocCtxt::Trait => + { + self.visit_vis(&item.vis); + self.visit_ident(item.ident); + walk_list!(self, visit_attribute, &item.attrs); + self.with_tilde_const_allowed(|this| { + this.visit_generics(generics); + walk_list!(this, visit_param_bound, bounds, BoundKind::Bound); + }); + walk_list!(self, visit_ty, ty); + } + AssocItemKind::Fn(box Fn { ref sig, ref generics, ref body, .. }) + if self.in_const_trait_impl + || ctxt == AssocCtxt::Trait + || matches!(sig.header.constness, Const::Yes(_)) => + { + self.visit_vis(&item.vis); + self.visit_ident(item.ident); + let kind = FnKind::Fn( + FnCtxt::Assoc(ctxt), + item.ident, + sig, + &item.vis, + generics, + body.as_deref(), + ); + self.visit_fn(kind, item.span, item.id); + } + _ => self + .with_in_trait_impl(false, None, |this| visit::walk_assoc_item(this, item, ctxt)), + } + } +} + +/// When encountering an equality constraint in a `where` clause, emit an error. If the code seems +/// like it's setting an associated type, provide an appropriate suggestion. +fn deny_equality_constraints( + this: &mut AstValidator<'_>, + predicate: &WhereEqPredicate, + generics: &Generics, +) { + let mut err = this.err_handler().struct_span_err( + predicate.span, + "equality constraints are not yet supported in `where` clauses", + ); + err.span_label(predicate.span, "not supported"); + + // Given `<A as Foo>::Bar = RhsTy`, suggest `A: Foo<Bar = RhsTy>`. + if let TyKind::Path(Some(qself), full_path) = &predicate.lhs_ty.kind { + if let TyKind::Path(None, path) = &qself.ty.kind { + match &path.segments[..] { + [PathSegment { ident, args: None, .. }] => { + for param in &generics.params { + if param.ident == *ident { + let param = ident; + match &full_path.segments[qself.position..] { + [PathSegment { ident, args, .. }] => { + // Make a new `Path` from `foo::Bar` to `Foo<Bar = RhsTy>`. + let mut assoc_path = full_path.clone(); + // Remove `Bar` from `Foo::Bar`. + assoc_path.segments.pop(); + let len = assoc_path.segments.len() - 1; + let gen_args = args.as_ref().map(|p| (**p).clone()); + // Build `<Bar = RhsTy>`. + let arg = AngleBracketedArg::Constraint(AssocConstraint { + id: rustc_ast::node_id::DUMMY_NODE_ID, + ident: *ident, + gen_args, + kind: AssocConstraintKind::Equality { + term: predicate.rhs_ty.clone().into(), + }, + span: ident.span, + }); + // Add `<Bar = RhsTy>` to `Foo`. + match &mut assoc_path.segments[len].args { + Some(args) => match args.deref_mut() { + GenericArgs::Parenthesized(_) => continue, + GenericArgs::AngleBracketed(args) => { + args.args.push(arg); + } + }, + empty_args => { + *empty_args = AngleBracketedArgs { + span: ident.span, + args: vec![arg], + } + .into(); + } + } + err.span_suggestion_verbose( + predicate.span, + &format!( + "if `{}` is an associated type you're trying to set, \ + use the associated type binding syntax", + ident + ), + format!( + "{}: {}", + param, + pprust::path_to_string(&assoc_path) + ), + Applicability::MaybeIncorrect, + ); + } + _ => {} + }; + } + } + } + _ => {} + } + } + } + // Given `A: Foo, A::Bar = RhsTy`, suggest `A: Foo<Bar = RhsTy>`. + if let TyKind::Path(None, full_path) = &predicate.lhs_ty.kind { + if let [potential_param, potential_assoc] = &full_path.segments[..] { + for param in &generics.params { + if param.ident == potential_param.ident { + for bound in ¶m.bounds { + if let ast::GenericBound::Trait(trait_ref, TraitBoundModifier::None) = bound + { + if let [trait_segment] = &trait_ref.trait_ref.path.segments[..] { + let assoc = pprust::path_to_string(&ast::Path::from_ident( + potential_assoc.ident, + )); + let ty = pprust::ty_to_string(&predicate.rhs_ty); + let (args, span) = match &trait_segment.args { + Some(args) => match args.deref() { + ast::GenericArgs::AngleBracketed(args) => { + let Some(arg) = args.args.last() else { + continue; + }; + ( + format!(", {} = {}", assoc, ty), + arg.span().shrink_to_hi(), + ) + } + _ => continue, + }, + None => ( + format!("<{} = {}>", assoc, ty), + trait_segment.span().shrink_to_hi(), + ), + }; + err.multipart_suggestion( + &format!( + "if `{}::{}` is an associated type you're trying to set, \ + use the associated type binding syntax", + trait_segment.ident, potential_assoc.ident, + ), + vec![(span, args), (predicate.span, String::new())], + Applicability::MaybeIncorrect, + ); + } + } + } + } + } + } + } + err.note( + "see issue #20041 <https://github.com/rust-lang/rust/issues/20041> for more information", + ); + err.emit(); +} + +pub fn check_crate(session: &Session, krate: &Crate, lints: &mut LintBuffer) -> bool { + let mut validator = AstValidator { + session, + extern_mod: None, + in_trait_impl: false, + in_const_trait_impl: false, + has_proc_macro_decls: false, + outer_impl_trait: None, + is_tilde_const_allowed: false, + is_impl_trait_banned: false, + is_assoc_ty_bound_banned: false, + forbidden_let_reason: Some(ForbiddenLetReason::GenericForbidden), + lint_buffer: lints, + }; + visit::walk_crate(&mut validator, krate); + + validator.has_proc_macro_decls +} + +/// Used to forbid `let` expressions in certain syntactic locations. +#[derive(Clone, Copy)] +enum ForbiddenLetReason { + /// `let` is not valid and the source environment is not important + GenericForbidden, + /// A let chain with the `||` operator + NotSupportedOr(Span), + /// A let chain with invalid parentheses + /// + /// For exemple, `let 1 = 1 && (expr && expr)` is allowed + /// but `(let 1 = 1 && (let 1 = 1 && (let 1 = 1))) && let a = 1` is not + NotSupportedParentheses(Span), +} diff --git a/compiler/rustc_ast_passes/src/feature_gate.rs b/compiler/rustc_ast_passes/src/feature_gate.rs new file mode 100644 index 000000000..789eca1f0 --- /dev/null +++ b/compiler/rustc_ast_passes/src/feature_gate.rs @@ -0,0 +1,901 @@ +use rustc_ast as ast; +use rustc_ast::visit::{self, AssocCtxt, FnCtxt, FnKind, Visitor}; +use rustc_ast::{AssocConstraint, AssocConstraintKind, NodeId}; +use rustc_ast::{PatKind, RangeEnd, VariantData}; +use rustc_errors::{struct_span_err, Applicability}; +use rustc_feature::{AttributeGate, BuiltinAttribute, 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; +use rustc_span::Span; + +use tracing::debug; + +macro_rules! gate_feature_fn { + ($visitor: expr, $has_feature: expr, $span: expr, $name: expr, $explain: expr, $help: expr) => {{ + let (visitor, has_feature, span, name, explain, help) = + (&*$visitor, $has_feature, $span, $name, $explain, $help); + let has_feature: bool = has_feature(visitor.features); + debug!("gate_feature(feature = {:?}, span = {:?}); has? {}", name, span, has_feature); + if !has_feature && !span.allows_unstable($name) { + feature_err_issue(&visitor.sess.parse_sess, name, span, GateIssue::Language, explain) + .help(help) + .emit(); + } + }}; + ($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, $help: expr) => { + gate_feature_fn!($visitor, |x: &Features| x.$feature, $span, sym::$feature, $explain, $help) + }; + ($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, + + // `sess` contains a `Features`, but this might not be that one. + features: &'a Features, +} + +impl<'a> PostExpansionVisitor<'a> { + fn check_abi(&self, abi: ast::StrLit, constness: ast::Const) { + let ast::StrLit { symbol_unescaped, span, .. } = abi; + + if let ast::Const::Yes(_) = constness { + match symbol_unescaped { + // Stable + sym::Rust | sym::C => {} + abi => gate_feature_post!( + &self, + const_extern_fn, + span, + &format!("`{}` as a `const fn` ABI is unstable", abi) + ), + } + } + + match symbol_unescaped.as_str() { + // Stable + "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" + ); + } + "rust-cold" => { + gate_feature_post!( + &self, + rust_cold_cc, + span, + "rust-cold is experimental and 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" + ); + } + "C-cmse-nonsecure-call" => { + gate_feature_post!( + &self, + abi_c_cmse_nonsecure_call, + span, + "C-cmse-nonsecure-call ABI is experimental and subject to change" + ); + } + "C-unwind" => { + gate_feature_post!( + &self, + c_unwind, + span, + "C-unwind ABI is experimental and subject to change" + ); + } + "stdcall-unwind" => { + gate_feature_post!( + &self, + c_unwind, + span, + "stdcall-unwind ABI is experimental and subject to change" + ); + } + "system-unwind" => { + gate_feature_post!( + &self, + c_unwind, + span, + "system-unwind ABI is experimental and subject to change" + ); + } + "thiscall-unwind" => { + gate_feature_post!( + &self, + c_unwind, + span, + "thiscall-unwind ABI is experimental and subject to change" + ); + } + "cdecl-unwind" => { + gate_feature_post!( + &self, + c_unwind, + span, + "cdecl-unwind ABI is experimental and subject to change" + ); + } + "fastcall-unwind" => { + gate_feature_post!( + &self, + c_unwind, + span, + "fastcall-unwind ABI is experimental and subject to change" + ); + } + "vectorcall-unwind" => { + gate_feature_post!( + &self, + c_unwind, + span, + "vectorcall-unwind ABI is experimental and subject to change" + ); + } + "aapcs-unwind" => { + gate_feature_post!( + &self, + c_unwind, + span, + "aapcs-unwind ABI is experimental and subject to change" + ); + } + "win64-unwind" => { + gate_feature_post!( + &self, + c_unwind, + span, + "win64-unwind ABI is experimental and subject to change" + ); + } + "sysv64-unwind" => { + gate_feature_post!( + &self, + c_unwind, + span, + "sysv64-unwind ABI is experimental and subject to change" + ); + } + "wasm" => { + gate_feature_post!( + &self, + wasm_abi, + span, + "wasm ABI is experimental and subject to change" + ); + } + abi => { + if self.sess.opts.pretty.map_or(true, |ppm| ppm.needs_hir()) { + 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, constness: ast::Const) { + if let ast::Extern::Explicit(abi, _) = ext { + self.check_abi(abi, constness); + } + } + + 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" + ); + } + } + + /// Feature gate `impl Trait` inside `type Alias = $type_expr;`. + fn check_impl_trait(&self, ty: &ast::Ty) { + struct ImplTraitVisitor<'a> { + vis: &'a PostExpansionVisitor<'a>, + } + impl Visitor<'_> for ImplTraitVisitor<'_> { + fn visit_ty(&mut self, ty: &ast::Ty) { + if let ast::TyKind::ImplTrait(..) = ty.kind { + gate_feature_post!( + &self.vis, + type_alias_impl_trait, + ty.span, + "`impl Trait` in type aliases is unstable" + ); + } + visit::walk_ty(self, ty); + } + } + ImplTraitVisitor { vis: self }.visit_ty(ty); + } +} + +impl<'a> Visitor<'a> for PostExpansionVisitor<'a> { + fn visit_attribute(&mut self, attr: &ast::Attribute) { + let attr_info = attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name)); + // Check feature gates for built-in attributes. + if let Some(BuiltinAttribute { + gate: AttributeGate::Gated(_, name, descr, has_feature), + .. + }) = attr_info + { + gate_feature_fn!(self, has_feature, attr.span, *name, descr); + } + // Check unstable flavors of the `#[doc]` attribute. + if attr.has_name(sym::doc) { + for nested_meta in attr.meta_item_list().unwrap_or_default() { + macro_rules! gate_doc { ($($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!( + cfg => doc_cfg + cfg_hide => doc_cfg_hide + masked => doc_masked + notable_trait => doc_notable_trait + ); + + if nested_meta.has_name(sym::keyword) { + let msg = "`#[doc(keyword)]` is meant for internal use only"; + gate_feature_post!(self, rustdoc_internals, attr.span, msg); + } + + if nested_meta.has_name(sym::fake_variadic) { + let msg = "`#[doc(fake_variadic)]` is meant for internal use only"; + gate_feature_post!(self, rustdoc_internals, attr.span, msg); + } + } + } + + // Emit errors for non-staged-api crates. + 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) + { + struct_span_err!( + self.sess, + attr.span, + E0734, + "stability attributes may not be used outside of the standard library", + ) + .emit(); + } + } + } + + 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::Const::No); + } + } + + ast::ItemKind::Fn(..) => { + 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" + ); + } + } + + 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(box ast::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_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_feature_post!(&self, specialization, i.span, "specialization is unstable"); + } + } + + ast::ItemKind::Trait(box ast::Trait { is_auto: 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(box ast::TyAlias { ty: 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 = + link_name.map_or(false, |val| val.as_str().starts_with("llvm.")); + 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) => { + // Function pointers cannot be `const` + self.check_extern(bare_fn_ty.ext, ast::Const::No); + } + 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 { + // Do nothing. + } else { + self.visit_ty(output_ty) + } + } + } + + fn visit_stmt(&mut self, stmt: &'a ast::Stmt) { + if let ast::StmtKind::Semi(expr) = &stmt.kind + && let ast::ExprKind::Assign(lhs, _, _) = &expr.kind + && let ast::ExprKind::Type(..) = lhs.kind + && self.sess.parse_sess.span_diagnostic.err_count() == 0 + && !self.features.type_ascription + && !lhs.span.allows_unstable(sym::type_ascription) + { + // When we encounter a statement of the form `foo: Ty = val;`, this will emit a type + // ascription error, but the likely intention was to write a `let` statement. (#78907). + feature_err_issue( + &self.sess.parse_sess, + sym::type_ascription, + lhs.span, + GateIssue::Language, + "type ascription is experimental", + ).span_suggestion_verbose( + lhs.span.shrink_to_lo(), + "you might have meant to introduce a new binding", + "let ".to_string(), + Applicability::MachineApplicable, + ).emit(); + } + visit::walk_stmt(self, stmt); + } + + 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(..) => { + // To avoid noise about type ascription in common syntax errors, only emit if it + // is the *only* error. + 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(_, Some(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::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_feature_post!( + &self, + half_open_range_patterns, + pat.span, + "`X..` patterns in slices are experimental" + ); + } + } + } + PatKind::Box(..) => { + gate_feature_post!( + &self, + box_patterns, + pattern.span, + "box pattern syntax is experimental" + ); + } + PatKind::Range(_, Some(_), 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() { + // Stability of const fn methods are covered in `visit_assoc_item` below. + self.check_extern(header.ext, header.constness); + } + + 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_assoc_constraint(&mut self, constraint: &'a AssocConstraint) { + if let AssocConstraintKind::Bound { .. } = constraint.kind { + gate_feature_post!( + &self, + associated_type_bounds, + constraint.span, + "associated type bounds are unstable" + ) + } + visit::walk_assoc_constraint(self, constraint) + } + + fn visit_assoc_item(&mut self, i: &'a ast::AssocItem, ctxt: AssocCtxt) { + let is_fn = match i.kind { + ast::AssocItemKind::Fn(_) => true, + ast::AssocItemKind::TyAlias(box ast::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() { + // Limit `min_specialization` to only specializing functions. + 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) + } +} + +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, $help:literal) => { + if let Some(spans) = spans.get(&sym::$gate) { + for span in spans { + gate_feature_post!(&visitor, $gate, *span, $msg, $help); + } + } + }; + ($gate:ident, $msg:literal) => { + if let Some(spans) = spans.get(&sym::$gate) { + for span in spans { + gate_feature_post!(&visitor, $gate, *span, $msg); + } + } + }; + } + gate_all!( + if_let_guard, + "`if let` guards are experimental", + "you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`" + ); + gate_all!(let_chains, "`let` expressions in this position are unstable"); + gate_all!( + async_closure, + "async closures are unstable", + "to use an async block, remove the `||`: `async {`" + ); + gate_all!( + closure_lifetime_binder, + "`for<...>` binders for closures are experimental", + "consider removing `for<...>`" + ); + gate_all!(more_qualified_paths, "usage of qualified paths in this context is experimental"); + gate_all!(generators, "yield syntax is experimental"); + gate_all!(raw_ref_op, "raw address of syntax is experimental"); + gate_all!(const_trait_impl, "const trait impls are experimental"); + gate_all!(half_open_range_patterns, "half-open range patterns are unstable"); + gate_all!(inline_const, "inline-const is experimental"); + gate_all!(inline_const_pat, "inline-const in pattern position is experimental"); + gate_all!(associated_const_equality, "associated const equality is incomplete"); + gate_all!(yeet_expr, "`do yeet` expression is experimental"); + + // All uses of `gate_all!` below this point were added in #65742, + // and subsequently disabled (with the non-early gating readded). + macro_rules! gate_all { + ($gate:ident, $msg:literal) => { + // FIXME(eddyb) do something more useful than always + // disabling these uses of early feature-gatings. + if false { + for span in spans.get(&sym::$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!(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"); + // To avoid noise about type ascription in common syntax errors, + // only emit if it is the *only* error. (Also check it last.) + 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) { + // checks if `#![feature]` has been used to enable any lang feature + // does not check the same for lib features unless there's at least one + // declared lang feature + if !sess.opts.unstable_features.is_nightly_build() { + let lang_features = &sess.features_untracked().declared_lang_features; + if lang_features.len() == 0 { + return; + } + for attr in krate.attrs.iter().filter(|attr| attr.has_name(sym::feature)) { + let mut err = 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)") + ); + 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 = lang_features + .iter() + .flat_map(|&(feature, _, since)| if feature == name { since } else { None }) + .next(); + if let Some(since) = stable_since { + err.help(&format!( + "the feature `{}` has been stable since {} and no longer requires \ + an attribute to enable", + name, since + )); + } else { + all_stable = false; + } + } + if all_stable { + err.span_suggestion( + attr.span, + "remove the attribute", + "", + Applicability::MachineApplicable, + ); + } + err.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(); + } + } + } +} diff --git a/compiler/rustc_ast_passes/src/lib.rs b/compiler/rustc_ast_passes/src/lib.rs new file mode 100644 index 000000000..9d52c3288 --- /dev/null +++ b/compiler/rustc_ast_passes/src/lib.rs @@ -0,0 +1,18 @@ +//! The `rustc_ast_passes` crate contains passes which validate the AST in `syntax` +//! parsed by `rustc_parse` and then lowered, after the passes in this crate, +//! by `rustc_ast_lowering`. +//! +//! The crate also contains other misc AST visitors, e.g. `node_count` and `show_span`. + +#![allow(rustc::potential_query_instability)] +#![feature(box_patterns)] +#![feature(if_let_guard)] +#![feature(iter_is_partitioned)] +#![feature(let_chains)] +#![feature(let_else)] +#![recursion_limit = "256"] + +pub mod ast_validation; +pub mod feature_gate; +pub mod node_count; +pub mod show_span; diff --git a/compiler/rustc_ast_passes/src/node_count.rs b/compiler/rustc_ast_passes/src/node_count.rs new file mode 100644 index 000000000..9c7369c83 --- /dev/null +++ b/compiler/rustc_ast_passes/src/node_count.rs @@ -0,0 +1,135 @@ +// Simply gives a rough count of the number of nodes in an AST. + +use rustc_ast::visit::*; +use rustc_ast::*; +use rustc_span::symbol::Ident; +use rustc_span::Span; + +pub struct NodeCounter { + pub count: usize, +} + +impl NodeCounter { + pub fn new() -> NodeCounter { + NodeCounter { count: 0 } + } +} + +impl<'ast> Visitor<'ast> for NodeCounter { + fn visit_ident(&mut self, _ident: Ident) { + self.count += 1; + } + fn visit_foreign_item(&mut self, i: &ForeignItem) { + self.count += 1; + walk_foreign_item(self, i) + } + fn visit_item(&mut self, i: &Item) { + self.count += 1; + walk_item(self, i) + } + fn visit_local(&mut self, l: &Local) { + self.count += 1; + walk_local(self, l) + } + fn visit_block(&mut self, b: &Block) { + self.count += 1; + walk_block(self, b) + } + fn visit_stmt(&mut self, s: &Stmt) { + self.count += 1; + walk_stmt(self, s) + } + fn visit_arm(&mut self, a: &Arm) { + self.count += 1; + walk_arm(self, a) + } + fn visit_pat(&mut self, p: &Pat) { + self.count += 1; + walk_pat(self, p) + } + fn visit_expr(&mut self, ex: &Expr) { + self.count += 1; + walk_expr(self, ex) + } + fn visit_ty(&mut self, t: &Ty) { + self.count += 1; + walk_ty(self, t) + } + fn visit_generic_param(&mut self, param: &GenericParam) { + self.count += 1; + walk_generic_param(self, param) + } + fn visit_generics(&mut self, g: &Generics) { + self.count += 1; + walk_generics(self, g) + } + fn visit_fn(&mut self, fk: visit::FnKind<'_>, s: Span, _: NodeId) { + self.count += 1; + walk_fn(self, fk, s) + } + fn visit_assoc_item(&mut self, ti: &AssocItem, ctxt: AssocCtxt) { + self.count += 1; + walk_assoc_item(self, ti, ctxt); + } + fn visit_trait_ref(&mut self, t: &TraitRef) { + self.count += 1; + walk_trait_ref(self, t) + } + fn visit_param_bound(&mut self, bounds: &GenericBound, _ctxt: BoundKind) { + self.count += 1; + walk_param_bound(self, bounds) + } + fn visit_poly_trait_ref(&mut self, t: &PolyTraitRef, m: &TraitBoundModifier) { + self.count += 1; + walk_poly_trait_ref(self, t, m) + } + fn visit_variant_data(&mut self, s: &VariantData) { + self.count += 1; + walk_struct_def(self, s) + } + fn visit_field_def(&mut self, s: &FieldDef) { + self.count += 1; + walk_field_def(self, s) + } + fn visit_enum_def( + &mut self, + enum_definition: &EnumDef, + generics: &Generics, + item_id: NodeId, + _: Span, + ) { + self.count += 1; + walk_enum_def(self, enum_definition, generics, item_id) + } + fn visit_variant(&mut self, v: &Variant) { + self.count += 1; + walk_variant(self, v) + } + fn visit_lifetime(&mut self, lifetime: &Lifetime, _: visit::LifetimeCtxt) { + self.count += 1; + walk_lifetime(self, lifetime) + } + fn visit_mac_call(&mut self, mac: &MacCall) { + self.count += 1; + walk_mac(self, mac) + } + fn visit_path(&mut self, path: &Path, _id: NodeId) { + self.count += 1; + walk_path(self, path) + } + fn visit_use_tree(&mut self, use_tree: &UseTree, id: NodeId, _nested: bool) { + self.count += 1; + walk_use_tree(self, use_tree, id) + } + fn visit_generic_args(&mut self, path_span: Span, generic_args: &GenericArgs) { + self.count += 1; + walk_generic_args(self, path_span, generic_args) + } + fn visit_assoc_constraint(&mut self, constraint: &AssocConstraint) { + self.count += 1; + walk_assoc_constraint(self, constraint) + } + fn visit_attribute(&mut self, _attr: &Attribute) { + self.count += 1; + } +} diff --git a/compiler/rustc_ast_passes/src/show_span.rs b/compiler/rustc_ast_passes/src/show_span.rs new file mode 100644 index 000000000..27637e311 --- /dev/null +++ b/compiler/rustc_ast_passes/src/show_span.rs @@ -0,0 +1,65 @@ +//! Span debugger +//! +//! This module shows spans for all expressions in the crate +//! to help with compiler debugging. + +use std::str::FromStr; + +use rustc_ast as ast; +use rustc_ast::visit; +use rustc_ast::visit::Visitor; + +enum Mode { + Expression, + Pattern, + Type, +} + +impl FromStr for Mode { + type Err = (); + fn from_str(s: &str) -> Result<Mode, ()> { + let mode = match s { + "expr" => Mode::Expression, + "pat" => Mode::Pattern, + "ty" => Mode::Type, + _ => return Err(()), + }; + Ok(mode) + } +} + +struct ShowSpanVisitor<'a> { + span_diagnostic: &'a rustc_errors::Handler, + mode: Mode, +} + +impl<'a> Visitor<'a> for ShowSpanVisitor<'a> { + fn visit_expr(&mut self, e: &'a ast::Expr) { + if let Mode::Expression = self.mode { + self.span_diagnostic.span_warn(e.span, "expression"); + } + visit::walk_expr(self, e); + } + + fn visit_pat(&mut self, p: &'a ast::Pat) { + if let Mode::Pattern = self.mode { + self.span_diagnostic.span_warn(p.span, "pattern"); + } + visit::walk_pat(self, p); + } + + fn visit_ty(&mut self, t: &'a ast::Ty) { + if let Mode::Type = self.mode { + self.span_diagnostic.span_warn(t.span, "type"); + } + visit::walk_ty(self, t); + } +} + +pub fn run(span_diagnostic: &rustc_errors::Handler, mode: &str, krate: &ast::Crate) { + let Ok(mode) = mode.parse() else { + return; + }; + let mut v = ShowSpanVisitor { span_diagnostic, mode }; + visit::walk_crate(&mut v, krate); +} |