lang/cc: rewrite init of irony-mode & compiler options

modules/lang/cc/autoload.el

@@ -64,18 +64,19 @@
    t))
 
 ;;;###autoload
-(defun +cc|irony-add-include-paths ()
+(defun +cc|irony-init-compile-options ()
-  "Seek out and add the nearest include/ folders to clang's options."
+  "Initialize compiler options for irony-mode. It searches for the nearest
-  (when-let (dir (locate-dominating-file buffer-file-name "include/"))
+compilation database and initailizes it. If none was found, it uses
-    (cl-pushnew (concat "-I" (expand-file-name "include/" dir))
+`+cc-c++-compiler-options'.
-                irony-additional-clang-options :test #'equal)))
+
+See https://github.com/Sarcasm/irony-mode#compilation-database for details on
+compilation dbs."
+  (when (memq major-mode '(c-mode c++-mode objc-mode))
+    (require 'irony-cdb)
+    (unless (irony-cdb-autosetup-compile-options)
+      (irony-cdb--update-compile-options
+       (append (delq nil (cdr-safe (assq major-mode +cc-compiler-options)))
+               (cl-loop for path in +cc-include-paths
+                        collect (format "-I %s" (shell-quote-argument path))))
+       (doom-project-root)))))
 
-;;;###autoload
-(defun +cc|use-c++11 ()
-  "Enable C++11 support with clang (via irony)."
-  (cl-pushnew "-std=c++11" irony-additional-clang-options :test #'equal)
-  (when IS-MAC
-    ;; NOTE beware: you'll get abi-inconsistencies when passing std-objects to
-    ;; libraries linked with libstdc++ (e.g. if you use boost which wasn't
-    ;; compiled with libc++)
-    (cl-pushnew "-stdlib=libc++" irony-additional-clang-options :test #'equal)))

modules/lang/cc/config.el

@@ -1,5 +1,30 @@
 ;;; lang/cc/config.el --- c, c++, and obj-c -*- lexical-binding: t; -*-
 
+(defvar +cc-include-paths (list "include/")
+  "A list of paths, relative to a project root, to search for headers in
+C/C++. Paths can be absolute.
+
+The purpose of this variable is to ensure syntax checkers and code-completion
+knows where to look for headers.")
+
+(defvar +cc-compiler-options
+  `((c-mode . nil)
+    (c++-mode
+     . ,(list "-std=c++11" ; use C++11 by default
+              (when IS-MAC
+                ;; NOTE beware: you'll get abi-inconsistencies when passing
+                ;; std-objects to libraries linked with libstdc++ (e.g. if you use
+                ;; boost which wasn't compiled with libc++)
+                (list "-stdlib=libc++"))))
+    (objc-mode . nil))
+  "A list of default compiler options for the C family. These are ignored if a
+compilation database is present in the project.")
+
+
+;;
+;; Plugins
+;;
+
 (def-package! cc-mode
   :commands (c-mode c++-mode objc-mode java-mode)
   :mode ("\\.mm" . objc-mode)
@@ -90,19 +115,14 @@
   :preface
   (setq irony-server-install-prefix (concat doom-etc-dir "irony-server/"))
   :init
-  (defun +cc|init-irony-mode ()
+  (add-hook! (c-mode c++-mode objc-mode) #'irony-mode)
-    ;; The major-mode check is necessary because some modes derive themselves
-    ;; from a c base mode, like java-mode or php-mode.
-    (when (and (memq major-mode '(c-mode c++-mode objc-mode))
-               (file-directory-p irony-server-install-prefix))
-      (irony-mode +1)))
-  (add-hook 'c-mode-common-hook #'+cc|init-irony-mode)
   :config
-  (make-variable-buffer-local 'irony-additional-clang-options)
+  (unless (file-directory-p irony-server-install-prefix)
-  ;; Add nearest include/ path to compiler options
+    (warn "irony-mode: server isn't installed; run M-x irony-install-server"))
-  (add-hook! '(c-mode-hook c++-mode-hook) #'+cc|irony-add-include-paths)
+
-  ;; Use C++11/14 by default
+  ;; Initialize compilation database, if present. Otherwise, fall back on
-  (add-hook 'c++-mode-hook #'+cc|use-c++11))
+  ;; `+cc-compiler-options'.
+  (add-hook 'irony-mode-hook #'+cc|irony-init-compile-options))
 
 (def-package! irony-eldoc
   :after irony