parse_all_token_trees cannot fail.

compiler/rustc_parse/src/parser/mod.rs

@@ -1288,12 +1288,12 @@ pub(crate) fn parse_token_tree(&mut self) -> TokenTree {
     }
 
     /// Parses a stream of tokens into a list of `TokenTree`s, up to EOF.
-    pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> {
+    pub fn parse_all_token_trees(&mut self) -> Vec<TokenTree> {
         let mut tts = Vec::new();
         while self.token != token::Eof {
             tts.push(self.parse_token_tree());
         }
-        Ok(tts)
+        tts
     }
 
     pub fn parse_tokens(&mut self) -> TokenStream {

src/librustdoc/clean/render_macro_matchers.rs

@@ -76,13 +76,7 @@ fn snippet_equal_to_token(tcx: TyCtxt<'_>, matcher: &TokenTree) -> Option<String
         };
 
     // Reparse a single token tree.
-    let mut reparsed_trees = match parser.parse_all_token_trees() {
-        Ok(reparsed_trees) => reparsed_trees,
-        Err(diagnostic) => {
-            diagnostic.cancel();
-            return None;
-        }
-    };
+    let mut reparsed_trees = parser.parse_all_token_trees();
     if reparsed_trees.len() != 1 {
         return None;
     }