ignore the knitr.unbalanced.chunk option and strictly prohibit unba…

…lanced chunk fences

NEWS.md

@@ -8,6 +8,10 @@
 
 - In-chunk references of the form `<<label>>` should not be resolved if `label` is not found in the document (thanks, @jennybc @gadenbuie, #2360).
 
+## MAJOR CHANGES
+
+- Unbalanced chunk delimiters (fences) in R Markdown documents are strictly prohibited now.
+
 # CHANGES IN knitr VERSION 1.48
 
 ## BUG FIXES

R/parser.R

@@ -470,17 +470,14 @@ match_chunk_end = function(pattern, line, i, b, lines) {
     if (!any(match_chunk_begin(pattern, lines[i + 1:(k - 1)], '^\\1`*\\\\{')))
       return(FALSE)
   }
-  # TODO: clean up the exceptions here (although perhaps some may never update again)
-  signal = if (getOption('knitr.unbalanced.chunk', FALSE)) warning2 else stop2
-  signal(
+  stop2(
     'The closing fence on line ', i, ' ("', line, '") in ', current_input(),
     ' does not match the opening fence "',
     gsub('\\^(\\s*`+).*', '\\1', pattern), '" on line ', b, '. You are recommended to ',
     'fix either the opening or closing fence of the code chunk to use exactly ',
     'the same numbers of backticks and same level of indentation (or blockquote). ',
     'See https://yihui.org/en/2021/10/unbalanced-delimiters/ for more info.'
   )
-  TRUE
 }
 
 #' Get all chunk labels in a document