Refactor Project API to reflect changes upstream

projectile-project-root no longer returns `default-directory` if not in
a project (it returns nil). As such, doom-project-* functions (and their
uses) have been refactored.

+ doom-project-p & doom-project-root are aliases for
  projectile-project-p & projectile-project-root.
+ doom-project-{p,root,name,expand} now has a DIR argument (for
  consistency, since projectile-project-name and
  projectile-project-expand do not).
+ The nocache parameter is no longer necessary, as projectile's caching
  behavior is now more sane.
+ Removed some projectile advice/hacks that are no longer necessary.
+ Updated unit tests

core/autoload/buffers.el

@@ -65,7 +65,7 @@ scratch buffer. See `doom-fallback-buffer-name' to change this."
 
 If no project is active, return all buffers."
   (let ((buffers (doom-buffer-list)))
-    (if-let* ((project-root (if (doom-project-p) (doom-project-root))))
+    (if-let* ((project-root (doom-project-root)))
         (cl-loop for buf in buffers
                  if (projectile-project-buffer-p buf project-root)
                  collect buf)

core/autoload/files.el

@@ -88,8 +88,8 @@ MATCH is a string regexp. Only entries that match it will be included."
       (recentf-add-file new-path))
     (recentf-remove-if-non-kept old-path))
   (when (and (bound-and-true-p projectile-mode)
-             (projectile-project-p)
-             (projectile-file-cached-p old-path (doom-project-root 'nocache)))
+             (doom-project-p)
+             (projectile-file-cached-p old-path (doom-project-root)))
     (projectile-purge-file-from-cache old-path))
   (when (bound-and-true-p save-place-mode)
     (save-place-forget-unreadable-files)))
@@ -111,7 +111,7 @@ MATCH is a string regexp. Only entries that match it will be included."
                             (list new-path))))
          (new-path-dir (file-name-directory new-path))
          (project-root (doom-project-root))
-         (short-new-name (if (file-in-directory-p new-path project-root)
+         (short-new-name (if (and project-root (file-in-directory-p new-path project-root))
                              (file-relative-name new-path project-root)
                            (abbreviate-file-name new-path))))
     (unless (file-directory-p new-path-dir)

core/autoload/projects.el

@@ -38,33 +38,23 @@ they are absolute."
 ;; Library
 
 ;;;###autoload
-(defun doom-project-p (&optional nocache)
-  "Return t if this buffer is currently in a project.
-If NOCACHE, don't fetch a cached answer."
-  (if nocache
-      (without-project-cache! (doom-project-p nil))
-    (let ((projectile-require-project-root t))
-      (and (projectile-project-p) t))))
+(defalias 'doom-project-p #'projectile-project-p)
 
 ;;;###autoload
-(defun doom-project-name (&optional nocache)
-  "Return the name of the current project.
-If NOCACHE, don't fetch a cached answer."
-  (if nocache
-      (without-project-cache! (doom-project-name nil))
-    (projectile-project-name)))
+(defalias 'doom-project-root #'projectile-project-root)
 
 ;;;###autoload
-(defun doom-project-root (&optional nocache)
-  "Returns the root of your project, or `default-directory' if none was found.
-If NOCACHE, don't fetch a cached answer."
-  (if nocache
-      (without-project-cache! (doom-project-root nil))
-    (let (projectile-require-project-root)
-      (projectile-project-root))))
+(defun doom-project-name (&optional dir)
+  "Return the name of the current project."
+  (let ((project-root (projectile-project-root dir)))
+    (if project-root
+        (funcall projectile-project-name-function project-root)
+      "-")))
 
 ;;;###autoload
-(defalias 'doom-project-expand #'projectile-expand-root)
+(defun doom-project-expand (name &optional dir)
+  "Expand NAME to project root."
+  (expand-file-name name (projectile-project-root dir)))
 
 ;;;###autoload
 (defun doom-project-find-file (dir)