tools/pdf: leave it to user to build epdfinfo

Trying to do this automatically is buggy to the point of insanity. It's
not reliable enough to use as a :post-build target for the pdf-tools
package.

Better to fail gracefully, let the user know what they must do, and let
them do it at their own discretion.

modules/tools/pdf/config.el

@@ -18,16 +18,21 @@
       (add-hook 'kill-buffer-hook #'+pdf-cleanup-windows-h nil t)))
 
   :config
-  ;; HACK `pdf-tools-install-noverify' tries to "reset" open pdf-view-mode
-  ;;      buffers, but does so incorrectly, causing errors when pdf-tools is
-  ;;      loaded after opening a pdf file. We've done its job ourselves in
-  ;;      `+pdf--install-epdfinfo-a' instead.
-  (defadvice! +pdf--inhibit-pdf-view-mode-resets-a (orig-fn &rest args)
-    :around #'pdf-tools-install-noverify
-    (letf! ((#'pdf-tools-pdf-buffer-p #'ignore))
-      (apply orig-fn args)))
-
-  (pdf-tools-install-noverify)
+  (defadvice! +pdf--install-epdfinfo-a (orig-fn &rest args)
+    "Install epdfinfo after the first PDF file, if needed."
+    :around #'pdf-view-mode
+    (if (file-executable-p pdf-info-epdfinfo-program)
+        (apply orig-fn args)
+      ;; If we remain in pdf-view-mode, it'll spit out cryptic errors. This
+      ;; graceful failure is better UX.
+      (fundamental-mode)
+      (message "Viewing PDFs in Emacs requires epdfinfo. Use `M-x pdf-tools-install' to build it")))
+
+  (when (memq 'pdf-occur-global-minor-mode pdf-tools-enabled-modes)
+    (pdf-occur-global-minor-mode 1))
+  (when (memq 'pdf-virtual-global-minor-mode pdf-tools-enabled-modes)
+    (pdf-virtual-global-minor-mode 1))
+  (add-hook 'pdf-view-mode-hook 'pdf-tools-enable-minor-modes)
 
   ;; For consistency with other special modes
   (map! :map pdf-view-mode-map :gn "q" #'kill-current-buffer)

modules/tools/pdf/packages.el

@@ -3,19 +3,7 @@
 
 (package! pdf-tools
   :recipe (:host github
-           :repo "vedang/pdf-tools"
-           :post-build
-           (let ((warning-minimum-log-level :error))
-             (require 'pdf-tools)
-             (unless (file-exists-p pdf-info-epdfinfo-program)
-               (require 'pdf-occur)
-               (print-group!
-                (print! (start "Building epdfinfo for pdf-tools"))
-                (with-current-buffer (pdf-tools-install 'no-query)
-                  (while compilation-in-progress
-                    (sleep-for 1))
-                  (when (> compilation-num-errors-found 0)
-                    (print! (warn "Failed to build epdfinfo because: %s" (buffer-string)))))))))
+           :repo "vedang/pdf-tools")
   :pin "d262cf9e19d57c6567e06e51d109150c20753839")
 
 (package! saveplace-pdf-view :pin "54ed966b842501c3c092dbf57b372e37b033c578")