--- /dev/null
+// 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, FnCtxt, FnKind, Visitor};
+use rustc_ast::walk_list;
+use rustc_ast::*;
+use rustc_ast_pretty::pprust;
+use rustc_data_structures::fx::FxHashMap;
+use rustc_errors::{error_code, pluralize, struct_span_err, Applicability};
+use rustc_parse::validate_attr;
+use rustc_session::lint::builtin::PATTERNS_IN_FNS_WITHOUT_BODY;
+use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer};
+use rustc_session::Session;
+use rustc_span::symbol::{kw, sym, Ident};
+use rustc_span::Span;
+use std::mem;
+use std::ops::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,
+}
+
+/// A syntactic context that disallows certain kinds of bounds (e.g., `?Trait` or `?const Trait`).
+#[derive(Clone, Copy)]
+enum BoundContext {
+ ImplTrait,
+ TraitBounds,
+ TraitObject,
+}
+
+impl BoundContext {
+ fn description(&self) -> &'static str {
+ match self {
+ Self::ImplTrait => "`impl Trait`",
+ Self::TraitBounds => "supertraits",
+ Self::TraitObject => "trait objects",
+ }
+ }
+}
+
+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,
+
+ 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>,
+
+ /// Keeps track of the `BoundContext` as we recurse.
+ ///
+ /// This is used to forbid `?const Trait` bounds in, e.g.,
+ /// `impl Iterator<Item = Box<dyn ?const Trait>`.
+ bound_context: Option<BoundContext>,
+
+ /// 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,
+
+ lint_buffer: &'a mut LintBuffer,
+}
+
+impl<'a> AstValidator<'a> {
+ fn with_in_trait_impl(&mut self, is_in: bool, f: impl FnOnce(&mut Self)) {
+ let old = mem::replace(&mut self.in_trait_impl, is_in);
+ f(self);
+ self.in_trait_impl = old;
+ }
+
+ 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_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_bound_context(BoundContext::ImplTrait, |this| f(this));
+ } else {
+ f(self)
+ }
+ self.outer_impl_trait = old;
+ }
+
+ fn with_bound_context(&mut self, ctx: BoundContext, f: impl FnOnce(&mut Self)) {
+ let old = self.bound_context.replace(ctx);
+ f(self);
+ self.bound_context = old;
+ }
+
+ fn visit_assoc_ty_constraint_from_generic_args(&mut self, constraint: &'a AssocTyConstraint) {
+ match constraint.kind {
+ AssocTyConstraintKind::Equality { .. } => {}
+ AssocTyConstraintKind::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_ty_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_bound_context(BoundContext::TraitObject, |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 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();
+ }
+ }
+
+ // FIXME(ecstaticmorse): Instead, use `bound_context` to check this in `visit_param_bound`.
+ fn no_questions_in_bounds(&self, bounds: &GenericBounds, where_: &str, is_trait: bool) {
+ for bound in bounds {
+ if let GenericBound::Trait(ref poly, TraitBoundModifier::Maybe) = *bound {
+ let mut err = self.err_handler().struct_span_err(
+ poly.span,
+ &format!("`?Trait` is not permitted in {}", where_),
+ );
+ if is_trait {
+ let path_str = pprust::path_to_string(&poly.trait_ref.path);
+ err.note(&format!("traits are `?{}` by default", path_str));
+ }
+ err.emit();
+ }
+ }
+ }
+
+ /// Matches `'-' lit | lit (cf. parser::Parser::parse_literal_maybe_minus)`,
+ /// or paths for ranges.
+ //
+ // FIXME: do we want to allow `expr -> pattern` conversion to create path expressions?
+ // That means making this work:
+ //
+ // ```rust,ignore (FIXME)
+ // struct S;
+ // macro_rules! m {
+ // ($a:expr) => {
+ // let $a = S;
+ // }
+ // }
+ // m!(S);
+ // ```
+ fn check_expr_within_pat(&self, expr: &Expr, allow_paths: bool) {
+ match expr.kind {
+ ExprKind::Lit(..) | ExprKind::ConstBlock(..) | ExprKind::Err => {}
+ ExprKind::Path(..) if allow_paths => {}
+ ExprKind::Unary(UnOp::Neg, ref inner) if matches!(inner.kind, ExprKind::Lit(_)) => {}
+ _ => self.err_handler().span_err(
+ expr.span,
+ "arbitrary expressions aren't allowed \
+ in patterns",
+ ),
+ }
+ }
+
+ 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_cvaradic_pos(fn_decl);
+ self.check_decl_attrs(fn_decl);
+ self.check_decl_self_param(fn_decl, self_semantic);
+ }
+
+ 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::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, \
+ 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.err_handler()
+ .struct_span_err(sp, msg)
+ .span_suggestion(
+ self.session.source_map().end_point(sp),
+ &format!("provide a definition for the {}", ctx),
+ sugg.to_string(),
+ Applicability::HasPlaceholders,
+ )
+ .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) {
+ 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),
+ String::new(),
+ 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(generics.where_clause.span, "`where` clauses", "`where` clause");
+ }
+ }
+
+ fn check_foreign_kind_bodyless(&self, ident: Ident, kind: &str, body: Option<Span>) {
+ let body = match body {
+ None => return,
+ Some(body) => body,
+ };
+ 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 body = match body {
+ None => return,
+ Some(body) => body,
+ };
+ 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",
+ ";".to_string(),
+ 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 ".to_string(),
+ Applicability::MaybeIncorrect,
+ )
+ .emit();
+ }
+ }
+
+ /// Reject C-varadic type unless the function is foreign,
+ /// or free and `unsafe extern "C"` semantically.
+ fn check_c_varadic_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 identifer 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",
+ String::new(),
+ Applicability::MachineApplicable,
+ )
+ .emit();
+ }
+ }
+
+ fn deny_super_traits(&self, bounds: &GenericBounds, ident_span: Span) {
+ if let [first @ last] | [first, .., last] = &bounds[..] {
+ let span = first.span().to(last.span());
+ struct_span_err!(self.session, span, E0568, "auto traits cannot have super traits")
+ .span_label(ident_span, "auto trait cannot have super traits")
+ .span_suggestion(
+ span,
+ "remove the super traits",
+ String::new(),
+ Applicability::MachineApplicable,
+ )
+ .emit();
+ }
+ }
+
+ 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();
+ struct_span_err!(
+ self.session,
+ spans,
+ E0380,
+ "auto traits cannot have methods or associated items"
+ )
+ .span_label(ident_span, "auto trait cannot have 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();
+ }
+}
+
+/// 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(
+ sess: &Session,
+ 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![];
+
+ for param in generics {
+ let ident = Some(param.ident.to_string());
+ let (kind, bounds, span) = (¶m.kind, Some(&*param.bounds), param.ident.span);
+ let (ord_kind, ident) = match ¶m.kind {
+ GenericParamKind::Lifetime => (ParamKindOrd::Lifetime, ident),
+ GenericParamKind::Type { default: _ } => (ParamKindOrd::Type, ident),
+ GenericParamKind::Const { ref ty, kw_span: _, default: _ } => {
+ let ty = pprust::ty_to_string(ty);
+ let unordered = sess.features_untracked().const_generics;
+ (ParamKindOrd::Const { unordered }, Some(format!("const {}: {}", param.ident, ty)))
+ }
+ };
+ if let Some(ident) = ident {
+ param_idents.push((kind, ord_kind, bounds, param_idents.len(), ident));
+ }
+ let max_param = &mut max_param;
+ 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),
+ };
+ }
+
+ let mut ordered_params = "<".to_string();
+ if !out_of_order.is_empty() {
+ 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 let Some(bounds) = bounds {
+ 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 => (),
+ // FIXME(const_generics_defaults)
+ GenericParamKind::Const { ty: _, kw_span: _, default: _ } => (),
+ }
+ 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,
+ &format!(
+ "reorder the parameters: lifetimes, {}",
+ if sess.features_untracked().const_generics {
+ "then consts and types"
+ } else {
+ "then types, then consts"
+ }
+ ),
+ ordered_params.clone(),
+ 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) {
+ match &expr.kind {
+ ExprKind::LlvmInlineAsm(..) if !self.session.target.allow_asm => {
+ struct_span_err!(
+ self.session,
+ expr.span,
+ E0472,
+ "llvm_asm! is unsupported on this target"
+ )
+ .emit();
+ }
+ _ => {}
+ }
+
+ visit::walk_expr(self, expr);
+ }
+
+ fn visit_ty(&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);
+ }
+ 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;
+ }
+ }
+ self.no_questions_in_bounds(bounds, "trait object types", false);
+ }
+ 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");
+ }
+
+ self.walk_ty(ty);
+ return;
+ }
+ _ => {}
+ }
+
+ 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) {
+ self.check_lifetime(lifetime.ident);
+ visit::walk_lifetime(self, lifetime);
+ }
+
+ 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 ImplKind {
+ unsafety,
+ polarity,
+ defaultness: _,
+ constness: _,
+ generics: _,
+ of_trait: Some(ref t),
+ ref self_ty,
+ items: _,
+ }) => {
+ self.with_in_trait_impl(true, |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();
+ }
+
+ visit::walk_item(this, item);
+ });
+ return; // Avoid visiting again.
+ }
+ ItemKind::Impl(box ImplKind {
+ 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 FnKind(def, _, _, ref body)) => {
+ self.check_defaultness(item.span, def);
+
+ if body.is_none() {
+ let msg = "free function without a body";
+ self.error_item_without_body(item.span, "function", msg, " { <body> }");
+ }
+ }
+ ItemKind::ForeignMod(ForeignMod { 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");
+ }
+ 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 TraitKind(
+ is_auto,
+ _,
+ ref generics,
+ ref bounds,
+ ref trait_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_items(trait_items, item.ident.span);
+ }
+ self.no_questions_in_bounds(bounds, "supertraits", true);
+
+ // 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_bound_context(BoundContext::TraitBounds, |this| {
+ walk_list!(this, visit_param_bound, bounds);
+ });
+ walk_list!(self, visit_assoc_item, trait_items, AssocCtxt::Trait);
+ walk_list!(self, visit_attribute, &item.attrs);
+ return;
+ }
+ ItemKind::Mod(Mod { inline, unsafety, .. }) => {
+ 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 !inline && !self.session.contains_name(&item.attrs, sym::path) {
+ self.check_mod_file_item_asciionly(item.ident);
+ }
+ }
+ ItemKind::Union(ref vdata, _) => {
+ if let VariantData::Tuple(..) | VariantData::Unit(..) = vdata {
+ self.err_handler()
+ .span_err(item.span, "tuple and unit unions are not permitted");
+ }
+ if vdata.fields().is_empty() {
+ self.err_handler().span_err(item.span, "unions cannot have zero fields");
+ }
+ }
+ 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 TyAliasKind(def, _, ref bounds, ref body)) => {
+ self.check_defaultness(item.span, def);
+ if body.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");
+ }
+ _ => {}
+ }
+
+ visit::walk_item(self, item)
+ }
+
+ fn visit_foreign_item(&mut self, fi: &'a ForeignItem) {
+ match &fi.kind {
+ ForeignItemKind::Fn(box FnKind(def, sig, _, body)) => {
+ self.check_defaultness(fi.span, *def);
+ self.check_foreign_fn_bodyless(fi.ident, body.as_deref());
+ self.check_foreign_fn_headerless(fi.ident, fi.span, sig.header);
+ }
+ ForeignItemKind::TyAlias(box TyAliasKind(def, generics, bounds, body)) => {
+ self.check_defaultness(fi.span, *def);
+ self.check_foreign_kind_bodyless(fi.ident, "type", body.as_ref().map(|b| b.span));
+ self.check_type_no_bounds(bounds, "`extern` blocks");
+ self.check_foreign_ty_genericless(generics);
+ }
+ ForeignItemKind::Static(_, _, body) => {
+ self.check_foreign_kind_bodyless(fi.ident, "static", body.as_ref().map(|b| b.span));
+ }
+ 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_ty_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_ty_default = None;
+ for param in &generics.params {
+ match param.kind {
+ GenericParamKind::Lifetime => (),
+ GenericParamKind::Type { default: Some(_), .. } => {
+ prev_ty_default = Some(param.ident.span);
+ }
+ GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => {
+ if let Some(span) = prev_ty_default {
+ let mut err = self.err_handler().struct_span_err(
+ span,
+ "type parameters with a default must be trailing",
+ );
+ if matches!(param.kind, GenericParamKind::Const { .. }) {
+ err.note(
+ "using type defaults and const parameters \
+ in the same parameter list is currently not permitted",
+ );
+ }
+ err.emit();
+ break;
+ }
+ }
+ }
+ }
+
+ validate_generic_param_order(
+ self.session,
+ 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);
+ }
+ }
+
+ visit::walk_generics(self, generics)
+ }
+
+ 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) {
+ match bound {
+ GenericBound::Trait(_, TraitBoundModifier::MaybeConst) => {
+ if let Some(ctx) = self.bound_context {
+ let msg = format!("`?const` is not permitted in {}", ctx.description());
+ self.err_handler().span_err(bound.span(), &msg);
+ }
+ }
+
+ GenericBound::Trait(_, TraitBoundModifier::MaybeConstMaybe) => {
+ self.err_handler()
+ .span_err(bound.span(), "`?const` and `?` are mutually exclusive");
+ }
+
+ _ => {}
+ }
+
+ visit::walk_param_bound(self, bound)
+ }
+
+ fn visit_pat(&mut self, pat: &'a Pat) {
+ match &pat.kind {
+ PatKind::Lit(expr) => {
+ self.check_expr_within_pat(expr, false);
+ }
+ PatKind::Range(start, end, _) => {
+ if let Some(expr) = start {
+ self.check_expr_within_pat(expr, true);
+ }
+ if let Some(expr) = end {
+ self.check_expr_within_pat(expr, true);
+ }
+ }
+ _ => {}
+ }
+
+ visit::walk_pat(self, pat)
+ }
+
+ fn visit_where_predicate(&mut self, p: &'a WherePredicate) {
+ if let &WherePredicate::BoundPredicate(ref bound_predicate) = p {
+ // A type binding, eg `for<'c> Foo: Send+Clone+'c`
+ self.check_late_bound_lifetime_defs(&bound_predicate.bound_generic_params);
+ }
+ visit::walk_where_predicate(self, p);
+ }
+
+ 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_varadic_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();
+ }
+
+ // 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();
+ }
+ });
+ }
+
+ visit::walk_fn(self, fk, span);
+ }
+
+ fn visit_assoc_item(&mut self, item: &'a AssocItem, ctxt: AssocCtxt) {
+ 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 FnKind(_, _, _, body)) => {
+ self.check_impl_item_provided(item.span, body, "function", " { <body> }");
+ }
+ AssocItemKind::TyAlias(box TyAliasKind(_, _, bounds, body)) => {
+ self.check_impl_item_provided(item.span, body, "type", " = <type>;");
+ self.check_type_no_bounds(bounds, "`impl`s");
+ }
+ _ => {}
+ }
+ }
+
+ if ctxt == AssocCtxt::Trait || self.in_trait_impl {
+ self.invalid_visibility(&item.vis, None);
+ if let AssocItemKind::Fn(box FnKind(_, 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");
+ }
+
+ self.with_in_trait_impl(false, |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(AssocTyConstraint {
+ id: rustc_ast::node_id::DUMMY_NODE_ID,
+ ident: *ident,
+ gen_args,
+ kind: AssocTyConstraintKind::Equality {
+ ty: predicate.rhs_ty.clone(),
+ },
+ 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,
+ );
+ }
+ _ => {}
+ };
+ }
+ }
+ }
+ _ => {}
+ }
+ }
+ }
+ 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,
+ has_proc_macro_decls: false,
+ outer_impl_trait: None,
+ bound_context: None,
+ is_impl_trait_banned: false,
+ is_assoc_ty_bound_banned: false,
+ lint_buffer: lints,
+ };
+ visit::walk_crate(&mut validator, krate);
+
+ validator.has_proc_macro_decls
+}
projects / rustc.git / blobdiff