Rollup merge of #57730 - Zoxc:combined-ast-validator, r=cramertj
Merge visitors in AST validation Cuts runtime for AST validation on `syntex_syntax` from 31.5 ms to 17 ms.
This commit is contained in:
Mazdak Farrokhzad
GitHub
commit
b0ec43f569
@ -6,6 +6,7 @@
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// This pass is supposed to perform only simple checks not requiring name resolution
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// or type checking or some other kind of complex analysis.
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use std::mem;
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use rustc::lint;
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use rustc::session::Session;
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use syntax::ast::*;
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@ -20,9 +21,73 @@ use errors::Applicability;
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struct AstValidator<'a> {
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session: &'a Session,
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// Used to ban nested `impl Trait`, e.g., `impl Into<impl Debug>`.
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// Nested `impl Trait` _is_ allowed in associated type position,
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// e.g `impl Iterator<Item=impl Debug>`
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outer_impl_trait: Option<Span>,
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// Used to ban `impl Trait` in path projections like `<impl Iterator>::Item`
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// or `Foo::Bar<impl Trait>`
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is_impl_trait_banned: bool,
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}
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impl<'a> AstValidator<'a> {
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fn with_banned_impl_trait(&mut self, f: impl FnOnce(&mut Self)) {
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let old = mem::replace(&mut self.is_impl_trait_banned, true);
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f(self);
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self.is_impl_trait_banned = old;
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}
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fn with_impl_trait(&mut self, outer_impl_trait: Option<Span>, f: impl FnOnce(&mut Self)) {
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let old = mem::replace(&mut self.outer_impl_trait, outer_impl_trait);
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f(self);
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self.outer_impl_trait = old;
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}
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// Mirrors visit::walk_ty, but tracks relevant state
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fn walk_ty(&mut self, t: &'a Ty) {
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match t.node {
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TyKind::ImplTrait(..) => {
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self.with_impl_trait(Some(t.span), |this| visit::walk_ty(this, t))
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}
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TyKind::Path(ref qself, ref path) => {
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// We allow these:
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// - `Option<impl Trait>`
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// - `option::Option<impl Trait>`
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// - `option::Option<T>::Foo<impl Trait>
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//
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// But not these:
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// - `<impl Trait>::Foo`
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// - `option::Option<impl Trait>::Foo`.
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//
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// To implement this, we disallow `impl Trait` from `qself`
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// (for cases like `<impl Trait>::Foo>`)
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// but we allow `impl Trait` in `GenericArgs`
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// iff there are no more PathSegments.
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if let Some(ref qself) = *qself {
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// `impl Trait` in `qself` is always illegal
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self.with_banned_impl_trait(|this| this.visit_ty(&qself.ty));
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}
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// Note that there should be a call to visit_path here,
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// so if any logic is added to process `Path`s a call to it should be
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// added both in visit_path and here. This code mirrors visit::walk_path.
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for (i, segment) in path.segments.iter().enumerate() {
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// Allow `impl Trait` iff we're on the final path segment
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if i == path.segments.len() - 1 {
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self.visit_path_segment(path.span, segment);
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} else {
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self.with_banned_impl_trait(|this| {
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this.visit_path_segment(path.span, segment)
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});
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}
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}
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}
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_ => visit::walk_ty(self, t),
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}
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}
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fn err_handler(&self) -> &errors::Handler {
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&self.session.diagnostic()
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}
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@ -267,6 +332,19 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
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self.no_questions_in_bounds(bounds, "trait object types", false);
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}
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TyKind::ImplTrait(_, ref bounds) => {
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if self.is_impl_trait_banned {
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struct_span_err!(self.session, ty.span, E0667,
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"`impl Trait` is not allowed in path parameters").emit();
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}
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if let Some(outer_impl_trait) = self.outer_impl_trait {
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struct_span_err!(self.session, ty.span, E0666,
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"nested `impl Trait` is not allowed")
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.span_label(outer_impl_trait, "outer `impl Trait`")
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.span_label(ty.span, "nested `impl Trait` here")
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.emit();
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}
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if !bounds.iter()
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.any(|b| if let GenericBound::Trait(..) = *b { true } else { false }) {
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self.err_handler().span_err(ty.span, "at least one trait must be specified");
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@ -275,7 +353,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
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_ => {}
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}
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visit::walk_ty(self, ty)
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self.walk_ty(ty)
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}
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fn visit_label(&mut self, label: &'a Label) {
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@ -414,6 +492,28 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
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visit::walk_foreign_item(self, fi)
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}
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// Mirrors visit::walk_generic_args, but tracks relevant state
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fn visit_generic_args(&mut self, _: Span, generic_args: &'a GenericArgs) {
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match *generic_args {
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GenericArgs::AngleBracketed(ref data) => {
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walk_list!(self, visit_generic_arg, &data.args);
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// Type bindings such as `Item=impl Debug` in `Iterator<Item=Debug>`
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// are allowed to contain nested `impl Trait`.
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self.with_impl_trait(None, |this| {
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walk_list!(this, visit_assoc_type_binding, &data.bindings);
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});
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}
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GenericArgs::Parenthesized(ref data) => {
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walk_list!(self, visit_ty, &data.inputs);
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if let Some(ref type_) = data.output {
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// `-> Foo` syntax is essentially an associated type binding,
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// so it is also allowed to contain nested `impl Trait`.
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self.with_impl_trait(None, |this| visit::walk_ty(this, type_));
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}
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}
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}
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}
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fn visit_generics(&mut self, generics: &'a Generics) {
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let mut seen_non_lifetime_param = false;
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let mut seen_default = None;
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@ -490,148 +590,10 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
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}
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}
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// Bans nested `impl Trait`, e.g., `impl Into<impl Debug>`.
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// Nested `impl Trait` _is_ allowed in associated type position,
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// e.g `impl Iterator<Item=impl Debug>`
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struct NestedImplTraitVisitor<'a> {
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session: &'a Session,
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outer_impl_trait: Option<Span>,
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}
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impl<'a> NestedImplTraitVisitor<'a> {
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fn with_impl_trait<F>(&mut self, outer_impl_trait: Option<Span>, f: F)
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where F: FnOnce(&mut NestedImplTraitVisitor<'a>)
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{
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let old_outer_impl_trait = self.outer_impl_trait;
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self.outer_impl_trait = outer_impl_trait;
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f(self);
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self.outer_impl_trait = old_outer_impl_trait;
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}
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}
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impl<'a> Visitor<'a> for NestedImplTraitVisitor<'a> {
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fn visit_ty(&mut self, t: &'a Ty) {
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if let TyKind::ImplTrait(..) = t.node {
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if let Some(outer_impl_trait) = self.outer_impl_trait {
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struct_span_err!(self.session, t.span, E0666,
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"nested `impl Trait` is not allowed")
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.span_label(outer_impl_trait, "outer `impl Trait`")
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.span_label(t.span, "nested `impl Trait` here")
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.emit();
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}
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self.with_impl_trait(Some(t.span), |this| visit::walk_ty(this, t));
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} else {
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visit::walk_ty(self, t);
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}
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}
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fn visit_generic_args(&mut self, _: Span, generic_args: &'a GenericArgs) {
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match *generic_args {
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GenericArgs::AngleBracketed(ref data) => {
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for arg in &data.args {
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self.visit_generic_arg(arg)
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}
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for type_binding in &data.bindings {
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// Type bindings such as `Item=impl Debug` in `Iterator<Item=Debug>`
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// are allowed to contain nested `impl Trait`.
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self.with_impl_trait(None, |this| visit::walk_ty(this, &type_binding.ty));
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}
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}
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GenericArgs::Parenthesized(ref data) => {
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for type_ in &data.inputs {
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self.visit_ty(type_);
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}
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if let Some(ref type_) = data.output {
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// `-> Foo` syntax is essentially an associated type binding,
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// so it is also allowed to contain nested `impl Trait`.
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self.with_impl_trait(None, |this| visit::walk_ty(this, type_));
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}
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}
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}
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}
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fn visit_mac(&mut self, _mac: &Spanned<Mac_>) {
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// covered in AstValidator
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}
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}
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// Bans `impl Trait` in path projections like `<impl Iterator>::Item` or `Foo::Bar<impl Trait>`.
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struct ImplTraitProjectionVisitor<'a> {
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session: &'a Session,
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is_banned: bool,
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}
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impl<'a> ImplTraitProjectionVisitor<'a> {
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fn with_ban<F>(&mut self, f: F)
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where F: FnOnce(&mut ImplTraitProjectionVisitor<'a>)
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{
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let old_is_banned = self.is_banned;
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self.is_banned = true;
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f(self);
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self.is_banned = old_is_banned;
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}
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}
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impl<'a> Visitor<'a> for ImplTraitProjectionVisitor<'a> {
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fn visit_ty(&mut self, t: &'a Ty) {
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match t.node {
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TyKind::ImplTrait(..) => {
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if self.is_banned {
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struct_span_err!(self.session, t.span, E0667,
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"`impl Trait` is not allowed in path parameters").emit();
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}
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}
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TyKind::Path(ref qself, ref path) => {
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// We allow these:
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// - `Option<impl Trait>`
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// - `option::Option<impl Trait>`
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// - `option::Option<T>::Foo<impl Trait>
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//
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// But not these:
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// - `<impl Trait>::Foo`
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// - `option::Option<impl Trait>::Foo`.
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//
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// To implement this, we disallow `impl Trait` from `qself`
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// (for cases like `<impl Trait>::Foo>`)
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// but we allow `impl Trait` in `GenericArgs`
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// iff there are no more PathSegments.
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if let Some(ref qself) = *qself {
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// `impl Trait` in `qself` is always illegal
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self.with_ban(|this| this.visit_ty(&qself.ty));
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}
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for (i, segment) in path.segments.iter().enumerate() {
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// Allow `impl Trait` iff we're on the final path segment
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if i == path.segments.len() - 1 {
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visit::walk_path_segment(self, path.span, segment);
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} else {
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self.with_ban(|this|
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visit::walk_path_segment(this, path.span, segment));
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}
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}
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}
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_ => visit::walk_ty(self, t),
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}
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}
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fn visit_mac(&mut self, _mac: &Spanned<Mac_>) {
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// covered in AstValidator
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}
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}
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pub fn check_crate(session: &Session, krate: &Crate) {
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visit::walk_crate(
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&mut NestedImplTraitVisitor {
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session,
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outer_impl_trait: None,
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}, krate);
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visit::walk_crate(
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&mut ImplTraitProjectionVisitor {
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session,
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is_banned: false,
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}, krate);
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visit::walk_crate(&mut AstValidator { session }, krate)
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visit::walk_crate(&mut AstValidator {
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session,
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outer_impl_trait: None,
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is_impl_trait_banned: false,
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}, krate)
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}
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