[elpa] externals/auctex 9fdfe2c 01/15: Re-implement auto-detect of path separator from kpsewhich output

[Tassilo Horn]

branch: externals/auctex
commit 9fdfe2c3d466d0a37b2d46b94052516e16d2c0c5
Author: Ikumi Keita <address@hidden>
Commit: Ikumi Keita <address@hidden>

    Re-implement auto-detect of path separator from kpsewhich output
    
    * tex.el (TeX-kpathsea-path-delimiter): Accept t for Autodetect again
    and make it default on w32 platform.
    (TeX-tree-expand): Use heuristics as much as possible to determine the
    path separator, paying attention to the case that it cannot be
    determined.
---
 tex.el | 48 +++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 39 insertions(+), 9 deletions(-)

diff --git a/tex.el b/tex.el
index 8eab9bc..f4f1b2e 100644
--- a/tex.el
+++ b/tex.el
@@ -2696,16 +2696,15 @@ If REGEXP is nil, or \"\", an error will occur."
          (setq answers (cons entry answers))))
     answers))
 
-(defcustom TeX-kpathsea-path-delimiter path-separator
+(defcustom TeX-kpathsea-path-delimiter
+  (if (memq system-type '(windows-nt cygwin)) t path-separator)
   "Path delimiter for kpathsea output.
-nil means kpathsea is disabled."
+t means autodetect, nil means kpathsea is disabled."
   :group 'TeX-file
   :type '(choice (const ":")
                 (const ";")
+                (const :tag "Autodetect" t)
                 (const :tag "Off" nil)))
-;; backward compatibility
-(when (eq TeX-kpathsea-path-delimiter t)
-  (setq TeX-kpathsea-path-delimiter path-separator))
 
 (defun TeX-tree-expand (vars program &optional subdirs)
   "Return directories corresponding to the kpathsea variables VARS.
@@ -2721,8 +2720,13 @@ are returned."
     (let* ((exit-status 1)
           (args `(,@(if program `("--progname" ,program))
                   "--expand-path"
-                  ,(mapconcat #'identity vars
-                              TeX-kpathsea-path-delimiter)))
+                  ;; It seems that kpsewhich accepts semicolon as
+                  ;; path delimiter even on non-w32 platform and
+                  ;; converts it to colon if necessary.
+                  ;; Quote from texmf.cnf of TeXLive 2017:
+                  ;; "In this file, either ; or : can be used to
+                  ;; separate path components."
+                  ,(mapconcat #'identity vars ";")))
           (path-list (ignore-errors
                        (with-output-to-string
                          (setq exit-status
@@ -2733,8 +2737,34 @@ are returned."
       (if (not (zerop exit-status))
          ;; kpsewhich is not available.  Disable subsequent usage.
          (setq TeX-kpathsea-path-delimiter nil)
-       (let ((separators (format "[\n\r%s]" TeX-kpathsea-path-delimiter))
-             path input-dir-list)
+       (let* ((delim
+               (cond
+                ;; If `TeX-kpathsea-path-delimiter' isn't t, use it
+                ;; for path delimiter.
+                ((not (eq TeX-kpathsea-path-delimiter t))
+                 TeX-kpathsea-path-delimiter)
+                ;; Otherwise, if the output begins with DOS drive
+                ;; letter or contains semicolon, we can set
+                ;; `TeX-kpathsea-path-delimiter' to ";" and use it
+                ;; for path delimiter.
+                ((string-match "^[A-Za-z]:\\|;" path-list)
+                 (setq TeX-kpathsea-path-delimiter ";"))
+                ;; Otherwise, if the output contains colon, we can set
+                ;; `TeX-kpathsea-path-delimiter' to ":" and use it
+                ;; for path delimiter.
+                ((string-match ":" path-list)
+                 (setq TeX-kpathsea-path-delimiter ":"))
+                ;; Otherwise, the output of this particular run
+                ;; happens to contain just one component (without any
+                ;; delimiter) of relative path (without DOS drive
+                ;; letter).
+                ;; It is safe to use ":" as delimiter for this case,
+                ;; but we cannot determine the value of
+                ;; `TeX-kpathsea-path-delimiter' now.
+                (t
+                 ":")))
+              (separators (format "[\n\r%s]" delim))
+              path input-dir-list)
          (dolist (item (condition-case nil
                            (split-string path-list separators t)
                          ;; COMPATIBILITY for XEmacs <= 21.4.15