Reject keyword lifetimes in parsing

Author: compiler-errors

compiler/rustc_ast/src/token.rs

@@ -662,6 +662,10 @@ impl Token {
     }
 
     /// Returns `true` if the token is a lifetime.
+    ///
+    /// This does not check that the lifetime is a *valid* lifetime -- for that,
+    /// you need to go through `expect_lifetime`, since we need to check that the
+    /// lifetime name is not reserved.
     pub fn is_lifetime(&self) -> bool {
         self.lifetime().is_some()
     }

compiler/rustc_ast_passes/messages.ftl

@@ -156,9 +156,6 @@ ast_passes_inherent_cannot_be = inherent impls cannot be {$annotation}
     .type = inherent impl for this type
     .only_trait = only trait implementations may be annotated with {$annotation}
 
-ast_passes_invalid_label =
-    invalid label name `{$name}`
-
 ast_passes_invalid_unnamed_field =
     unnamed fields are not allowed outside of structs or unions
     .label = unnamed field declared here
@@ -170,9 +167,6 @@ ast_passes_invalid_unnamed_field_ty =
 ast_passes_item_underscore = `{$kind}` items in this context need a name
     .label = `_` is not a valid name for this `{$kind}` item
 
-ast_passes_keyword_lifetime =
-    lifetimes cannot use keyword names
-
 ast_passes_match_arm_with_no_body =
     `match` arm with no body
     .suggestion = add a body after the pattern

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -257,19 +257,6 @@ impl<'a> AstValidator<'a> {
         self.session.dcx()
     }
 
-    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.dcx().emit_err(errors::KeywordLifetime { span: ident.span });
-        }
-    }
-
-    fn check_label(&self, ident: Ident) {
-        if ident.without_first_quote().is_reserved() {
-            self.dcx().emit_err(errors::InvalidLabel { span: ident.span, name: ident.name });
-        }
-    }
-
     fn visibility_not_permitted(&self, vis: &Visibility, note: errors::VisibilityNotPermittedNote) {
         if let VisibilityKind::Inherited = vis.kind {
             return;
@@ -879,16 +866,6 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
         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, field: &'a FieldDef) {
         self.deny_unnamed_field(field);
         visit::walk_field_def(self, field)
@@ -1315,9 +1292,6 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
     }
 
     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);
     }
 

compiler/rustc_ast_passes/src/errors.rs

@@ -9,21 +9,6 @@ use rustc_span::{symbol::Ident, Span, Symbol};
 
 use crate::fluent_generated as fluent;
 
-#[derive(Diagnostic)]
-#[diag(ast_passes_keyword_lifetime)]
-pub struct KeywordLifetime {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(ast_passes_invalid_label)]
-pub struct InvalidLabel {
-    #[primary_span]
-    pub span: Span,
-    pub name: Symbol,
-}
-
 #[derive(Diagnostic)]
 #[diag(ast_passes_visibility_not_permitted, code = E0449)]
 pub struct VisibilityNotPermitted {

compiler/rustc_parse/messages.ftl

@@ -390,6 +390,9 @@ parse_invalid_dyn_keyword = invalid `dyn` keyword
 parse_invalid_expression_in_let_else = a `{$operator}` expression cannot be directly assigned in `let...else`
 parse_invalid_identifier_with_leading_number = identifiers cannot start with a number
 
+parse_invalid_label =
+    invalid label name `{$name}`
+
 parse_invalid_literal_suffix_on_tuple_index = suffixes on a tuple index are invalid
     .label = invalid suffix `{$suffix}`
     .tuple_exception_line_1 = `{$suffix}` is *temporarily* accepted on tuple index fields as it was incorrectly accepted on stable for a few releases
@@ -416,6 +419,9 @@ parse_invalid_unicode_escape = invalid unicode character escape
 parse_invalid_variable_declaration =
     invalid variable declaration
 
+parse_keyword_lifetime =
+    lifetimes cannot use keyword names
+
 parse_kw_bad_case = keyword `{$kw}` is written in the wrong case
     .suggestion = write it in the correct case
 

compiler/rustc_parse/src/errors.rs

@@ -1907,6 +1907,21 @@ pub struct CannotBeRawIdent {
     pub ident: Symbol,
 }
 
+#[derive(Diagnostic)]
+#[diag(parse_keyword_lifetime)]
+pub struct KeywordLifetime {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(parse_invalid_label)]
+pub struct InvalidLabel {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+}
+
 #[derive(Diagnostic)]
 #[diag(parse_cr_doc_comment)]
 pub struct CrDocComment {

compiler/rustc_parse/src/parser/expr.rs

@@ -2931,10 +2931,25 @@ impl<'a> Parser<'a> {
     }
 
     pub(crate) fn eat_label(&mut self) -> Option<Label> {
-        self.token.lifetime().map(|(ident, _)| {
+        if let Some((ident, is_raw)) = self.token.lifetime() {
+            // Disallow `'fn`, but with a better error message than `expect_lifetime`.
+            if matches!(is_raw, IdentIsRaw::No)
+                && ident.without_first_quote().is_reserved()
+                && ![kw::UnderscoreLifetime, kw::StaticLifetime].contains(&ident.name)
+            {
+                self.dcx().emit_err(errors::InvalidLabel { span: ident.span, name: ident.name });
+            }
+
+            // Disallow `'_: loop {}`
+            if [kw::StaticLifetime, kw::UnderscoreLifetime].contains(&ident.name) {
+                self.dcx().emit_err(errors::InvalidLabel { span: ident.span, name: ident.name });
+            }
+
             self.bump();
-            Label { ident }
-        })
+            Some(Label { ident })
+        } else {
+            None
+        }
     }
 
     /// Parses a `match ... { ... }` expression (`match` token already eaten).

compiler/rustc_parse/src/parser/pat.rs

@@ -539,12 +539,12 @@ impl<'a> Parser<'a> {
                     None => PatKind::Path(qself, path),
                 }
             }
-        } else if let token::Lifetime(lt, IdentIsRaw::No) = self.token.kind
+        } else if let Some((lt, IdentIsRaw::No)) = self.token.lifetime()
             // In pattern position, we're totally fine with using "next token isn't colon"
             // as a heuristic. We could probably just always try to recover if it's a lifetime,
             // because we never have `'a: label {}` in a pattern position anyways, but it does
             // keep us from suggesting something like `let 'a: Ty = ..` => `let 'a': Ty = ..`
-            && could_be_unclosed_char_literal(Ident::with_dummy_span(lt))
+            && could_be_unclosed_char_literal(lt)
             && !self.look_ahead(1, |token| matches!(token.kind, token::Colon))
         {
             // Recover a `'a` as a `'a'` literal
@@ -672,11 +672,13 @@ impl<'a> Parser<'a> {
     /// Parse `&pat` / `&mut pat`.
     fn parse_pat_deref(&mut self, expected: Option<Expected>) -> PResult<'a, PatKind> {
         self.expect_and()?;
-        if let token::Lifetime(name, _) = self.token.kind {
+        if let Some((lifetime, _)) = self.token.lifetime() {
             self.bump(); // `'a`
 
-            self.dcx()
-                .emit_err(UnexpectedLifetimeInPattern { span: self.prev_token.span, symbol: name });
+            self.dcx().emit_err(UnexpectedLifetimeInPattern {
+                span: self.prev_token.span,
+                symbol: lifetime.name,
+            });
         }
 
         let mutbl = self.parse_mutability();

compiler/rustc_parse/src/parser/ty.rs

@@ -9,7 +9,7 @@ use crate::errors::{
 use crate::{maybe_recover_from_interpolated_ty_qpath, maybe_whole};
 
 use rustc_ast::ptr::P;
-use rustc_ast::token::{self, Delimiter, Token, TokenKind};
+use rustc_ast::token::{self, Delimiter, IdentIsRaw, Token, TokenKind};
 use rustc_ast::util::case::Case;
 use rustc_ast::{
     self as ast, BareFnTy, BoundAsyncness, BoundConstness, BoundPolarity, FnRetTy, GenericBound,
@@ -1201,7 +1201,14 @@ impl<'a> Parser<'a> {
 
     /// Parses a single lifetime `'a` or panics.
     pub(super) fn expect_lifetime(&mut self) -> Lifetime {
-        if let Some((ident, _)) = self.token.lifetime() {
+        if let Some((ident, is_raw)) = self.token.lifetime() {
+            if matches!(is_raw, IdentIsRaw::No)
+                && ident.without_first_quote().is_reserved()
+                && ![kw::UnderscoreLifetime, kw::StaticLifetime].contains(&ident.name)
+            {
+                self.dcx().emit_err(errors::KeywordLifetime { span: ident.span });
+            }
+
             self.bump();
             Lifetime { ident, id: ast::DUMMY_NODE_ID }
         } else {

tests/ui/lifetimes/kw-lifetime-nonterminal.rs

@@ -0,0 +1,9 @@
+//@ check-pass
+
+macro_rules! t {
+    ($lt:lifetime) => {};
+}
+
+t!('fn);
+
+fn main() {}

tests/ui/parser/require-parens-for-chained-comparison.rs

@@ -24,12 +24,14 @@ fn main() {
     //~| HELP use `::<...>` instead of `<...>` to specify lifetime, type, or const arguments
     //~| ERROR expected
     //~| HELP add `'` to close the char literal
+    //~| ERROR invalid label name
 
     f<'_>();
     //~^ comparison operators cannot be chained
     //~| HELP use `::<...>` instead of `<...>` to specify lifetime, type, or const arguments
     //~| ERROR expected
     //~| HELP add `'` to close the char literal
+    //~| ERROR invalid label name
 
     let _ = f<u8>;
     //~^ ERROR comparison operators cannot be chained

tests/ui/parser/require-parens-for-chained-comparison.stderr

@@ -53,6 +53,12 @@ help: use `::<...>` instead of `<...>` to specify lifetime, type, or const argum
 LL |     let _ = f::<u8, i8>();
    |              ++
 
+error: invalid label name `'_`
+  --> $DIR/require-parens-for-chained-comparison.rs:22:15
+   |
+LL |     let _ = f<'_, i8>();
+   |               ^^
+
 error: expected `while`, `for`, `loop` or `{` after a label
   --> $DIR/require-parens-for-chained-comparison.rs:22:17
    |
@@ -75,8 +81,14 @@ help: use `::<...>` instead of `<...>` to specify lifetime, type, or const argum
 LL |     let _ = f::<'_, i8>();
    |              ++
 
+error: invalid label name `'_`
+  --> $DIR/require-parens-for-chained-comparison.rs:29:7
+   |
+LL |     f<'_>();
+   |       ^^
+
 error: expected `while`, `for`, `loop` or `{` after a label
-  --> $DIR/require-parens-for-chained-comparison.rs:28:9
+  --> $DIR/require-parens-for-chained-comparison.rs:29:9
    |
 LL |     f<'_>();
    |         ^ expected `while`, `for`, `loop` or `{` after a label
@@ -87,7 +99,7 @@ LL |     f<'_'>();
    |         +
 
 error: comparison operators cannot be chained
-  --> $DIR/require-parens-for-chained-comparison.rs:28:6
+  --> $DIR/require-parens-for-chained-comparison.rs:29:6
    |
 LL |     f<'_>();
    |      ^  ^
@@ -98,13 +110,13 @@ LL |     f::<'_>();
    |      ++
 
 error: comparison operators cannot be chained
-  --> $DIR/require-parens-for-chained-comparison.rs:34:14
+  --> $DIR/require-parens-for-chained-comparison.rs:36:14
    |
 LL |     let _ = f<u8>;
    |              ^  ^
    |
    = help: use `::<...>` instead of `<...>` to specify lifetime, type, or const arguments
    = help: or use `(...)` if you meant to specify fn arguments
 
-error: aborting due to 10 previous errors
+error: aborting due to 12 previous errors
 

tests/ui/self/self_type_keyword.stderr

@@ -4,6 +4,12 @@ error: expected identifier, found keyword `Self`
 LL |   struct Self;
    |          ^^^^ expected identifier, found keyword
 
+error: lifetimes cannot use keyword names
+  --> $DIR/self_type_keyword.rs:6:12
+   |
+LL | struct Bar<'Self>;
+   |            ^^^^^
+
 error: expected identifier, found keyword `Self`
   --> $DIR/self_type_keyword.rs:14:13
    |
@@ -48,12 +54,6 @@ error: expected identifier, found keyword `Self`
 LL |     trait Self {}
    |           ^^^^ expected identifier, found keyword
 
-error: lifetimes cannot use keyword names
-  --> $DIR/self_type_keyword.rs:6:12
-   |
-LL | struct Bar<'Self>;
-   |            ^^^^^
-
 error: cannot find macro `Self` in this scope
   --> $DIR/self_type_keyword.rs:21:9
    |