Add manual completion function to ycmd layer

layers/+tools/ycmd/README.org

@@ -9,6 +9,7 @@
 - [[#configuration][Configuration]]
   - [[#activating-ycmd-in-a-major-mode][Activating ycmd in a major mode]]
   - [[#getting-the-compilation-flags][Getting the compilation flags]]
+- [[#functions][Functions]]
 - [[#key-bindings][Key Bindings]]
 
 * Description
@@ -85,6 +86,23 @@ If your build system doesn't handle the creation of a compile_commands.json,
 you can use tools such as [[https://github.com/rizsotto/Bear][Bear]] or [[https://pypi.python.org/pypi/scan-build][scan-build]] to generate it, which both work
 with almost any build system.
 
+* Functions
+
+If ~company-ycmd~ is used, then a function
+~spacemacs/company-ycmd-manual-semantic-complete~ is defined. This function is
+useful if you want to get semantic completions only when you press a
+keybinding; in larger projects ycmd may not be performant for as-you-type
+auto-completion to work well. You can bind it like so:
+
+#+BEGIN_SRC emacs-lisp
+(global-set-key (kbd "<C-tab>") 'spacemacs/company-ycmd-manual-semantic-complete)
+#+END_SRC
+
+This function will automatically cancel out of any active completers, and offer
+semantic completions. It will automatically make an exception when you are
+completing includes; these do not count as semantic completion so the exception
+is necessary for the keybinding to work when completing includes.
+
 * Key Bindings
 Adds ~SPC m g g~ go to definition binding to =c++-mode= as well as ~SPC m g G~
 for the more imprecise but faster version.

layers/+tools/ycmd/funcs.el

@@ -0,0 +1,7 @@
+(when (configuration-layer/package-usedp 'company-ycmd)
+  (defun spacemacs/company-ycmd-manual-semantic-complete ()
+    (interactive)
+    (company-cancel)
+    (let ((ycmd-force-semantic-completion (not (company-ycmd--in-include))))
+      (setq company-backend 'company-ycmd)
+      (company-manual-begin))))