address review comments

compiler/rustc_parse/messages.ftl

@@ -468,9 +468,6 @@ 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
@@ -500,6 +497,8 @@ parse_invalid_unicode_escape = invalid unicode character escape
 parse_invalid_variable_declaration =
     invalid variable declaration
 
+parse_keyword_label = labels cannot use keyword names
+
 parse_keyword_lifetime =
     lifetimes cannot use keyword names
 

compiler/rustc_parse/src/errors.rs

@@ -2228,11 +2228,10 @@ pub(crate) struct KeywordLifetime {
 }
 
 #[derive(Diagnostic)]
-#[diag(parse_invalid_label)]
-pub(crate) struct InvalidLabel {
+#[diag(parse_keyword_label)]
+pub(crate) struct KeywordLabel {
     #[primary_span]
     pub span: Span,
-    pub name: String,
 }
 
 #[derive(Diagnostic)]

compiler/rustc_parse/src/parser/expr.rs

@@ -3094,13 +3094,7 @@ impl<'a> Parser<'a> {
         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() {
-                self.dcx().emit_err(errors::InvalidLabel {
-                    span: ident.span,
-                    // `IntoDiagArg` prints the symbol as if it was an ident,
-                    // so `'break` is printed as `r#break`. We don't want that
-                    // here so convert to string eagerly.
-                    name: ident.without_first_quote().name.to_string(),
-                });
+                self.dcx().emit_err(errors::KeywordLabel { span: ident.span });
             }
 
             self.bump();

compiler/rustc_parse/src/parser/ty.rs

@@ -1479,8 +1479,7 @@ impl<'a> Parser<'a> {
     pub(super) fn expect_lifetime(&mut self) -> 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)
+                && ident.without_first_quote().is_reserved_lifetime()
             {
                 self.dcx().emit_err(errors::KeywordLifetime { span: ident.span });
             }

compiler/rustc_span/src/symbol.rs

@@ -3045,13 +3045,17 @@ impl Ident {
         self.name.can_be_raw() && self.is_reserved()
     }
 
+    /// Given the name of a lifetime without the first quote (`'`),
+    /// returns whether the lifetime name is reserved (therefore invalid)
+    pub fn is_reserved_lifetime(self) -> bool {
+        self.is_reserved() && ![kw::Underscore, kw::Static].contains(&self.name)
+    }
+
     pub fn is_raw_lifetime_guess(self) -> bool {
-        // this should be kept consistent with `Parser::expect_lifetime` found under
-        // compiler/rustc_parse/src/parser/ty.rs
         let name_without_apostrophe = self.without_first_quote();
         name_without_apostrophe.name != self.name
-            && ![kw::UnderscoreLifetime, kw::StaticLifetime].contains(&self.name)
-            && name_without_apostrophe.is_raw_guess()
+            && name_without_apostrophe.name.can_be_raw()
+            && name_without_apostrophe.is_reserved_lifetime()
     }
 
     pub fn guess_print_mode(self) -> IdentPrintMode {

tests/ui/closures/issue-52437.rs

@@ -1,5 +1,5 @@
 fn main() {
     [(); &(&'static: loop { |x| {}; }) as *const _ as usize]
-    //~^ ERROR: invalid label name `static`
+    //~^ ERROR: labels cannot use keyword names
     //~| ERROR: type annotations needed
 }

tests/ui/closures/issue-52437.stderr

@@ -1,4 +1,4 @@
-error: invalid label name `static`
+error: labels cannot use keyword names
   --> $DIR/issue-52437.rs:2:13
    |
 LL |     [(); &(&'static: loop { |x| {}; }) as *const _ as usize]

tests/ui/issues/issue-46311.rs

@@ -1,4 +1,4 @@
 fn main() {
-    'break: loop { //~ ERROR invalid label name `break`
+    'break: loop { //~ ERROR labels cannot use keyword names
     }
 }

tests/ui/issues/issue-46311.stderr

@@ -1,4 +1,4 @@
-error: invalid label name `break`
+error: labels cannot use keyword names
   --> $DIR/issue-46311.rs:2:5
    |
 LL |     'break: loop {

tests/ui/label/label-static.rs

@@ -1,5 +1,5 @@
 fn main() {
-    'static: loop { //~ ERROR invalid label name `static`
-        break 'static //~ ERROR invalid label name `static`
+    'static: loop { //~ ERROR labels cannot use keyword names
+        break 'static //~ ERROR labels cannot use keyword names
     }
 }

tests/ui/label/label-static.stderr

@@ -1,10 +1,10 @@
-error: invalid label name `static`
+error: labels cannot use keyword names
   --> $DIR/label-static.rs:2:5
    |
 LL |     'static: loop {
    |     ^^^^^^^
 
-error: invalid label name `static`
+error: labels cannot use keyword names
   --> $DIR/label-static.rs:3:15
    |
 LL |         break 'static

tests/ui/label/label-underscore.rs

@@ -1,5 +1,5 @@
 fn main() {
-    '_: loop { //~ ERROR invalid label name `_`
-        break '_ //~ ERROR invalid label name `_`
+    '_: loop { //~ ERROR labels cannot use keyword names
+        break '_ //~ ERROR labels cannot use keyword names
     }
 }

tests/ui/label/label-underscore.stderr

@@ -1,10 +1,10 @@
-error: invalid label name `_`
+error: labels cannot use keyword names
   --> $DIR/label-underscore.rs:2:5
    |
 LL |     '_: loop {
    |     ^^
 
-error: invalid label name `_`
+error: labels cannot use keyword names
   --> $DIR/label-underscore.rs:3:15
    |
 LL |         break '_

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

@@ -24,14 +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
+    //~| ERROR labels cannot use keyword names
 
     f<'_>();
     //~^ ERROR 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
+    //~| ERROR labels cannot use keyword names
 
     let _ = f<u8>;
     //~^ ERROR comparison operators cannot be chained

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

@@ -53,7 +53,7 @@ help: use `::<...>` instead of `<...>` to specify lifetime, type, or const argum
 LL |     let _ = f::<u8, i8>();
    |              ++
 
-error: invalid label name `_`
+error: labels cannot use keyword names
   --> $DIR/require-parens-for-chained-comparison.rs:22:15
    |
 LL |     let _ = f<'_, i8>();
@@ -81,7 +81,7 @@ help: use `::<...>` instead of `<...>` to specify lifetime, type, or const argum
 LL |     let _ = f::<'_, i8>();
    |              ++
 
-error: invalid label name `_`
+error: labels cannot use keyword names
   --> $DIR/require-parens-for-chained-comparison.rs:29:7
    |
 LL |     f<'_>();