Make expand_invalid_fragment_specifier translatable

Author: Xiretza

compiler/rustc_expand/messages.ftl

@@ -91,7 +91,7 @@ expand_invalid_cfg_predicate_literal = `cfg` predicate key cannot be a literal
 
 expand_invalid_fragment_specifier =
     invalid fragment specifier `{$fragment}`
-    .help = {$help}
+    .help = valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`
 
 expand_macro_body_stability =
     macros cannot have body stability attributes

compiler/rustc_expand/src/errors.rs

@@ -447,7 +447,6 @@ pub struct InvalidFragmentSpecifier {
     #[primary_span]
     pub span: Span,
     pub fragment: Ident,
-    pub help: String,
 }
 
 #[derive(Diagnostic)]

compiler/rustc_expand/src/mbe/quoted.rs

@@ -13,10 +13,6 @@ use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::edition::Edition;
 use rustc_span::Span;
 
-const VALID_FRAGMENT_NAMES_MSG: &str = "valid fragment specifiers are \
-                                        `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, \
-                                        `literal`, `path`, `meta`, `tt`, `item` and `vis`";
-
 /// Takes a `tokenstream::TokenStream` and returns a `Vec<self::TokenTree>`. Specifically, this
 /// takes a generic `TokenStream`, such as is used in the rest of the compiler, and returns a
 /// collection of `TokenTree` for use in parsing a macro.
@@ -86,7 +82,6 @@ pub(super) fn parse(
                                                     errors::InvalidFragmentSpecifier {
                                                         span,
                                                         fragment,
-                                                        help: VALID_FRAGMENT_NAMES_MSG.into(),
                                                     },
                                                 );
                                                 token::NonterminalKind::Ident