Cannot add tikz code snippet in my .Rmd post using blogdown - rstudio

Question

I have just started using blogdown and I have created a project by using template Hugo-Xmin. In RStudio, when creating the project in blogdown, it created some predefined posts, I am editing this one:
/content/post/2015-07-23-r-rmarkdown.Rmd
Adding a tikz image
Following this question and the bookdown documentation on engines, I modified the afore-mentioned file by adding this snippet:
This is a tikz picture:
```{r, echo=FALSE, engine='tikz', out.width='90%', fig.ext=if (knitr:::is_latex_output()) 'pdf' else 'png', fig.cap='Some caption.'}
\begin{tikzpicture}[scale=.7]
\draw [fill=gray!30,very thick] (0,-1) rectangle (5,1);
\draw [very thick] (5, 0) -- (13,0);
\node [below] at (2,-1) {\large Hello};
\node [below, align=center] at (0,-1) {\large Two\\ lines};
\end{tikzpicture}
```
Failed to process the post
As soon as I save (since I have the serve on), but also when using blogdown::build_site(), I get this:
> blogdown::serve_site()
Rendering content/post/2015-07-23-r-rmarkdown.Rmd
This is pdfTeX, Version 3.14159265-2.6-1.40.19 (TeX Live 2018/W32TeX) (preloaded format=pdflatex)
restricted \write18 enabled.
entering extended mode
Quitting from lines 49-55 (2015-07-23-r-rmarkdown.Rmd)
Error: Failed to compile .\tikz53878cd6189.tex. See https://yihui.name/tinytex/r/#debugging for debugging tips.
Execution halted
Error in render_page(f) :
Failed to render 'content/post/2015-07-23-r-rmarkdown.Rmd'
Troubleshooting
I checked my engines and saw that tikz is actually among them:
> names(knitr::knit_engines$get())
[1] "awk" "bash" "coffee" "gawk" "groovy" "haskell" "lein" "mysql"
[9] "node" "octave" "perl" "psql" "Rscript" "ruby" "sas" "scala"
[17] "sed" "sh" "stata" "zsh" "highlight" "Rcpp" "tikz" "dot"
[25] "c" "fortran" "fortran95" "asy" "cat" "asis" "stan" "block"
[33] "block2" "js" "css" "sql" "go" "python" "julia" "theorem"
[41] "lemma" "corollary" "proposition" "conjecture" "definition" "example" "exercise" "proof"
[49] "remark" "solution"
The documentation said that some engines are shipped in bookdown and not knitr, but I can see tikz is there! So I have the engine, but still I cannot use it. What am I doing wrong?
More info
A log file /content/post/texput.log is generated and reports this info on the failure:
This is pdfTeX, Version 3.14159265-2.6-1.40.19 (TeX Live 2018/W32TeX) (preloaded format=pdflatex 2019.1.11) 25 FEB 2019 07:54
entering extended mode
restricted \write18 enabled.
%&-line parsing enabled.
**.\tikz3cac449b1071.tex
! Emergency stop.
<*> .\tikz3cac449b1071.tex
*** (job aborted, file error in nonstop mode)
Here is how much of TeX's memory you used:
3 strings out of 492616
115 string characters out of 6132768
56950 words of memory out of 5000000
4017 multiletter control sequences out of 15000+600000
3640 words of font info for 14 fonts, out of 8000000 for 9000
1141 hyphenation exceptions out of 8191
0i,0n,0p,1b,6s stack positions out of 5000i,500n,10000p,200000b,80000s
! ==> Fatal error occurred, no output PDF file produced!
If I check knitr:
> xfun::session_info('knitr')
R version 3.5.2 (2018-12-20)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows >= 8 x64 (build 9200), RStudio 1.1.463
Locale:
LC_COLLATE=English_United States.1252 LC_CTYPE=English_United States.1252
LC_MONETARY=English_United States.1252 LC_NUMERIC=C
LC_TIME=English_United States.1252
Package version:
evaluate_0.13 glue_1.3.0 graphics_3.5.2 grDevices_3.5.2 highr_0.7 knitr_1.21.13
magrittr_1.5 markdown_0.9 methods_3.5.2 mime_0.6 stats_3.5.2 stringi_1.3.1
stringr_1.4.0 tools_3.5.2 utils_3.5.2 xfun_0.5 yaml_2.2.0

Answer 1

This turns out to be an issue in knitr which I just fixed on Github (I'm not sure if it is a bug of pdflatex). You may try
remotes::install_github('yihui/knitr')
Note that you will need to install two additional R packages, magick and pdftools, if they haven't been installed yet.