[PATCH] Avoid ignoring LaTeX export output errors when org-latex-pdf-process is a list

[Ihor Radchenko]

Hi,

The attached patch is fixing a rather annoying problem when
org-latex-pdf-process is set to a list. Currently, only output of the
last command in the list is preserved in *Org PDF LaTeX output* buffer,
which sometimes prevents ox-latex from detecting compilation warnings.

ox-latex relies on *Org PDF LaTeX output* to contain the output of latex
compiler. However, unless the last command in the org-latex-pdf-process
is something like pdflatex, the compiler errors are erased by
`shell-command' called by `org-compile-file'.

Best,
Ihor

>From d4f15ed260f47195b01cb60061b57823428d2eef Mon Sep 17 00:00:00 2001
Message-Id: 
<d4f15ed260f47195b01cb60061b57823428d2eef.1653191200.git.yantar92@gmail.com>
From: Ihor Radchenko <yantar92@gmail.com>
Date: Sun, 22 May 2022 11:44:56 +0800
Subject: [PATCH] Avoid ignoring LaTeX export output errors

* lisp/org-macs.el (org-compile-file): When PROCESS is a list, keep
output of all the listed commands, not just the last one.
* lisp/ox-latex.el (org-latex-pdf-process): Clarify that the process
output is parsed to detect compilation errors/warnings.
---
 lisp/org-macs.el | 9 +++++++--
 lisp/ox-latex.el | 3 +++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/lisp/org-macs.el b/lisp/org-macs.el
index 10eed2686..2a7131ded 100644
--- a/lisp/org-macs.el
+++ b/lisp/org-macs.el
@@ -323,8 +323,13 @@ (defun org-compile-file (source process ext &optional 
err-msg log-buf spec)
                               (?F . ,(shell-quote-argument full-name))
                               (?o . ,(shell-quote-argument out-dir))
                               (?O . ,(shell-quote-argument output))))))
-          (dolist (command process)
-            (shell-command (format-spec command spec) log-buf))
+           ;; Combine output of all commands in PROCESS.
+           (with-current-buffer log-buf
+             (let (buffer-read-only)
+               (erase-buffer)))
+           (let ((shell-command-dont-erase-buffer t))
+            (dolist (command process)
+              (shell-command (format-spec command spec) log-buf)))
           (when log-buf (with-current-buffer log-buf (compilation-mode)))))
        (_ (error "No valid command to process %S%s" source err-msg))))
     ;; Check for process failure.  Output file is expected to be
diff --git a/lisp/ox-latex.el b/lisp/ox-latex.el
index 5a2de8afb..ed16ec46f 100644
--- a/lisp/ox-latex.el
+++ b/lisp/ox-latex.el
@@ -1426,6 +1426,9 @@ (defcustom org-latex-pdf-process
       "%latex -interaction nonstopmode -output-directory %o %f"))
   "Commands to process a LaTeX file to a PDF file.
 
+The command output will be parsed to extract compilation errors and
+warnings according to `org-latex-known-warnings'.
+
 This is a list of strings, each of them will be given to the
 shell as a command.  %f in the command will be replaced by the
 relative file name, %F by the absolute file name, %b by the file
-- 
2.35.1