fix #2599: 7420791 introduced a bug for .md input because knitr::is_latex_output() only works for .Rmd but not for .md; we still check pandoc_to here but also consider the possibility that the output format may include extensions (hence testing -+.* after latex|beamer)

Author: yihui

DESCRIPTION

@@ -1,7 +1,7 @@
 Type: Package
 Package: rmarkdown
 Title: Dynamic Documents for R
-Version: 2.29.4
+Version: 2.29.5
 Authors@R: c(
     person("JJ", "Allaire", , "[email protected]", role = "aut"),
     person("Yihui", "Xie", , "[email protected]", role = c("aut", "cre"), comment = c(ORCID = "0000-0003-0645-5666")),

NEWS.md

@@ -9,6 +9,8 @@ rmarkdown 2.30
 
 - `convert_ipynb()` no longer drops raw cells with no `format` in metadata (thanks, @katrinabrock, #2587).
 
+- Fixed a bug that prevents `render()` from working when converting `.md` input to PDF (thanks, @mrainers, #2599).
+
 
 rmarkdown 2.29
 ================================================================================

R/render.R

@@ -979,7 +979,7 @@ render <- function(input,
     # if the output format is LaTeX, first convert .md to .tex, and then convert
     # .tex to .pdf via latexmk() if PDF output is requested (in rmarkdown <=
     # v1.8, we used to call Pandoc to convert .md to .tex and .pdf separately)
-    if (output_format$pandoc$keep_tex || knitr::is_latex_output()) {
+    if (output_format$pandoc$keep_tex || grepl("^(latex|beamer)($|[-+].*)", pandoc_to)) {
       # do not use pandoc-citeproc if needs to build bibliography
       convert(texfile, run_citeproc && !need_bibtex)
       # patch the .tex output generated from the default Pandoc LaTeX template