(tex-compilation-parse-errors): Added. At the moment, this would have

to be applied manually.  It's not worth trying to integrate this with
the rest of the mode more tightly until we decide whether and how
compile's interface is going to change away from a closed subsystem.

lisp/textmodes/tex-mode.el

@@ -6,7 +6,7 @@
 ;; Keywords: tex
 
 ;; Contributions over the years by William F. Schelter, Dick King,
-;; Stephen Gildea, Michael Prange, and Edward M. Reingold.
+;; Stephen Gildea, Michael Prange, and Jacob Gore.
 
 ;; This file is part of GNU Emacs.
 
@@ -28,6 +28,7 @@
 
 ;; This was a pain.  Now, make-comint should autoload comint.
 ;; (require 'comint)
+(require 'compile)
 
 ;;;###autoload
 (defvar tex-shell-file-name nil
@@ -608,6 +609,81 @@ Puts point on a blank line between them."
     (insert "\\end" text)
     (if new-line-needed (insert ?\n))))
 
+(defun tex-compilation-parse-errors ()
+  "Parse the current buffer as error messages.
+This makes a list of error descriptors, compilation-error-list.
+For each source-file, line-number pair in the buffer,
+the source file is read in, and the text location is saved in
+compilation-error-list.  The function next-error, assigned to
+\\[next-error], takes the next error off the list and visits its location.
+
+This function works on TeX compilations only.  It is necessary for
+that purpose, since TeX does not put file names on the same line as
+line numbers for the errors."
+  (setq compilation-error-list nil)
+  (message "Parsing error messages...")
+  (modify-syntax-entry ?\{ "_")
+  (modify-syntax-entry ?\} "_")
+  (modify-syntax-entry ?\[ "_")
+  (modify-syntax-entry ?\] "_")
+  (make-variable-buffer-local 'compilation-error-regexp)
+  (setq compilation-error-regexp "^l\.[0-9]+ ")
+  (let (text-buffer
+	last-filename last-linenum)
+    ;; Don't reparse messages already seen at last parse.
+    (goto-char compilation-parsing-end)
+    ;; Don't parse the first two lines as error messages.
+    ;; This matters for grep.
+    (if (bobp)
+	(forward-line 2))
+    (while (re-search-forward compilation-error-regexp nil t)
+      (let (linenum filename
+	    error-marker text-marker)
+	;; Extract file name and line number from error message.
+	;; Line number is 2 away from beginning of line: "l.23"
+	(beginning-of-line)
+	(goto-char (+ (point) 2))
+	(setq linenum (read (current-buffer)))
+	;; The file is the one that was opened last and is still open.
+	;; We need to find the last open parenthesis.
+	(insert ?\))
+	(backward-sexp)
+	(forward-char)
+	(setq filename (compilation-grab-filename))
+	;; Locate the erring file and line.
+	(if (and (equal filename last-filename)
+		 (= linenum last-linenum))
+	    nil
+	  (skip-chars-backward "^(")
+	  (backward-char)
+	  (forward-sexp)
+	  (backward-delete-char 1)
+	  (setq error-marker (point-marker))
+	  ;; text-buffer gets the buffer containing this error's file.
+	  (if (not (equal filename last-filename))
+	      (setq text-buffer
+		    (and (file-exists-p (setq last-filename filename))
+			 (find-file-noselect filename))
+		    last-linenum 0))
+	  (if text-buffer
+	      ;; Go to that buffer and find the erring line.
+	      (save-excursion
+		(set-buffer text-buffer)
+		(if (zerop last-linenum)
+		    (progn
+		      (goto-char 1)
+		      (setq last-linenum 1)))
+		(forward-line (- linenum last-linenum))
+		(setq last-linenum linenum)
+		(setq text-marker (point-marker))
+		(setq compilation-error-list
+		      (cons (list error-marker text-marker)
+			    compilation-error-list)))))
+	(forward-line 1)))
+    (setq compilation-parsing-end (point-max)))
+  (message "Parsing error messages...done")
+  (setq compilation-error-list (nreverse compilation-error-list)))
+
 ;;; Invoking TeX in an inferior shell.
 
 ;;; Why use a shell instead of running TeX directly?  Because if TeX