Hello R-devel, I had been using an Rd trick that runs afoul of the changes in r81965[*]. After the change, there seems to be a problem with any user-defined macro that takes R code, forwards it to \Sexpr and gets passed a string literal containing '{': \newcommand{\RRd}{\Sexpr[stage=build,results=rd]{#1}} \RRd{x <- 'a string with { inside it'; 'okay'} R-4.1.3: okay R-devel: Error: x.Rd: '\{' is an unrecognized escape in character string starting "'a string with \{" Execution halted My actual use case is a macro that forwards its argument to \Sexpr{tools::toRd(bibentry(...))}. I've been trying to pass \enc{}{} as an argument to bibentry; previously, I had to use a workaround to create the backslash, but now any braces (in addition to backslashes) inside string literals also result in errors: \newcommand{\bib}{\Sexpr[stage=build,results=rd]{bibentry(#1)}} \bib{'Misc', author = person('J.', 'Doe'), year = 2022, title = paste0( 'A ', rawToChar(as.raw(0x5c)), 'enc{m??se}{moose} bit my sister once' # ^-----^^-----^--- in these four places ) } R-4.1.3: Doe J (2022). ?A m??se bit my sister once.? R-devel: Error: x.Rd: '\{' is an unrecognized escape in character string starting "'enc\{" Execution halted Should I have relied upon \Sexpr{#1} working inside user-defined macros? Georgi N. Boshnakov's Rdpack does similar things (and has been an inspiration for my tricks). I'll be glad to re-write some of my Rd to achieve the same result using less crazy tricks, assuming there is a right way to do that. -- Best regards, Ivan [*] https://github.com/r-devel/r-svn/commit/7ccd166735e6b978023b85fc9aa4845af8c0c241