The attached log is generated by previewing the following document with xelatex:
\documentclass{article}
\begin{document}
Test: $풞$
\end{document}
The unicode character in math mode after "Test: " is U+1D49E.
The preview range for the snippet is completely wrong and includes the
entire line before the snipped. It appears that there are some encoding
problems because the log file refers to a unicode character U+D49E,
which is the lowest 16 bits of the original character's codepoint.
Emacs : GNU Emacs 26.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.30)
of 2018-07-05
Package: 12.1.1
Run buffer contents:
Running `Preview-LaTeX' on `test' with ``xelatex --synctex=1 -file-line-error
"\nonstopmode\nofiles\PassOptionsToPackage{active,tightpage,auctex}{preview}\AtBeginDocument{\ifx\ifPreview\undefined\RequirePackage[displaymath,floats,graphics,textmath,sections,footnotes]{preview}[2004/11/05]\fi}"
"\input" test.tex''
This is XeTeX, Version 3.14159265-2.6-0.9 (TeX Live 2018/Arch Linux)
(preloaded format=xelatex)
restricted \write18 enabled.
entering extended mode
LaTeX2e <2018-04-01> patch level 2
Babel <3.18> and hyphenation patterns for 84 language(s) loaded.
No auxiliary output files.
(./test.tex (/usr/share/texmf-dist/tex/latex/base/article.cls
Document Class: article 2014/09/29 v1.4h Standard LaTeX document class
(/usr/share/texmf-dist/tex/latex/base/size10.clo)) (./test.aux)
(/home/noname/.emacs.d/elpa/auctex-12.1.1/latex/preview.sty
(/usr/share/texmf-dist/tex/generic/luatex85/luatex85.sty)
(/home/noname/.emacs.d/elpa/auctex-12.1.1/latex/prtightpage.def)
(/home/noname/.emacs.d/elpa/auctex-12.1.1/latex/prauctex.def
No auxiliary output files.
(/home/noname/.emacs.d/elpa/auctex-12.1.1/latex/prauctex.cfg))
(/home/noname/.emacs.d/elpa/auctex-12.1.1/latex/prfootnotes.def)
Preview: Fontsize 10pt
Preview: PDFoutput 1
)
./test.tex:5: Preview: Snippet 1 started.
<-><->
l.5 Test: $
풞$
Preview: Tightpage -32891 -32891 32891 32891
./test.tex:5: Preview: Snippet 1 ended.(0+0x0).
<-><->
l.5 Test: $풞$
[1] )
(see the transcript file for additional information)
Output written on test.pdf (1 page).
SyncTeX written on test.synctex.gz.
Transcript written on test.log.
TeX Output exited as expected with code 1 at Thu Aug 2 01:59:30
Running `Preview-PDF2DSC' with ``pdf2dsc test.pdf
test.prv/tmp2pIiJl/preview.dsc''
Preview-PDF2DSC finished at Thu Aug 2 01:59:30
Running `Preview-Ghostscript' with ``/usr/bin/rungs
-dOutputFile\=\(test.prv/tmp2pIiJl/pr1-\%d.png\) -q -dDELAYSAFER -dNOPAUSE
-DNOPLATFONTS -dPrinted -dTextAlphaBits\=4 -dGraphicsAlphaBits\=4
-sDEVICE\=png16m -r94.08x93.9321''
Preview-Ghostscript finished at Thu Aug 2 01:59:30
current state:
==
(setq
AUCTeX-version "12.1.1"
LaTeX-command-style '(("" "%(PDF)%(latex) %(extraopts) %S%(PDFout)
-file-line-error"))
image-types '(svg imagemagick png gif tiff jpeg xpm xbm pbm postscript)
preview-image-type 'png
preview-image-creators '((dvipng (open preview-gs-open
preview-dvipng-process-setup) (place preview-gs-place)
(close preview-dvipng-close))
(png (open preview-gs-open) (place preview-gs-place)
(close preview-gs-close))
(jpeg (open preview-gs-open) (place preview-gs-place)
(close preview-gs-close))
(pnm (open preview-gs-open) (place preview-gs-place)
(close preview-gs-close))
(tiff (open preview-gs-open) (place preview-gs-place)
(close preview-gs-close)))
preview-dvipng-image-type 'png
preview-dvipng-command "dvipng -picky -noghostscript %d -o
\"%m/prev%%03d.png\""
preview-pdf2dsc-command "pdf2dsc %s.pdf %m/preview.dsc"
preview-gs-command "/usr/bin/rungs"
preview-gs-options '("-q" "-dDELAYSAFER" "-dNOPAUSE" "-DNOPLATFONTS"
"-dPrinted" "-dTextAlphaBits=4"
"-dGraphicsAlphaBits=4")
preview-gs-image-type-alist '((png png "-sDEVICE=png16m") (dvipng png
"-sDEVICE=png16m")
(jpeg jpeg "-sDEVICE=jpeg") (pnm pbm
"-sDEVICE=pnmraw")
(tiff tiff "-sDEVICE=tiff12nc"))
preview-fast-conversion t
preview-prefer-TeX-bb nil
preview-dvips-command "dvips -Pwww -i -E %d -o %m/preview.000"
preview-fast-dvips-command "dvips -Pwww %d -o %m/preview.ps"
preview-scale-function 'preview-scale-from-face
preview-LaTeX-command '("%`%l \"\\nonstopmode\\nofiles\\PassOptionsToPackage{"
("," . preview-required-option-list)
"}{preview}\\AtBeginDocument{\\ifx\\ifPreview\\undefined"
preview-default-preamble
"\\fi}\"%' %t")
preview-required-option-list '("active" "tightpage" "auctex"
(preview-preserve-counters "counters"))
preview-preserve-counters nil
preview-default-option-list '("displaymath" "floats" "graphics" "textmath"
"sections" "footnotes")
preview-default-preamble '("\\RequirePackage[" ("," .
