[helm] Provide fuzzy matching for Helm-M-x

Following the advice from duianto #13100 we are
setting completion-styles for helm-M-x to include
the emacs version specific fuzzy strategy as last
resort.

Before no fuzzy matching occured within command
searches.

layers/+completion/helm/funcs.el

@@ -114,8 +114,8 @@ If DEFAULT-INPUTP is non nil then the current region or symbol at point
   (interactive)
   (call-interactively
    (spacemacs//helm-do-search-find-tool "helm-file-do"
-                                 dotspacemacs-search-tools
-                                 default-inputp)))
+                                        dotspacemacs-search-tools
+                                        default-inputp)))
 
 (defun spacemacs/helm-file-smart-do-search-region-or-symbol ()
   "Search in current file using `dotspacemacs-search-tools' with
@@ -183,8 +183,8 @@ If DEFAULT-INPUTP is non nil then the current region or symbol at point
   (interactive)
   (call-interactively
    (spacemacs//helm-do-search-find-tool "helm-files-do"
-                                 dotspacemacs-search-tools
-                                 default-inputp)))
+                                        dotspacemacs-search-tools
+                                        default-inputp)))
 
 (defun spacemacs/helm-files-smart-do-search-region-or-symbol ()
   "Search in files using `dotspacemacs-search-tools' with default input.
@@ -247,8 +247,8 @@ If DEFAULT-INPUTP is non nil then the current region or symbol at point
   (interactive)
   (call-interactively
    (spacemacs//helm-do-search-find-tool "helm-dir-do"
-                                 dotspacemacs-search-tools
-                                 default-inputp)))
+                                        dotspacemacs-search-tools
+                                        default-inputp)))
 
 (defun spacemacs/helm-dir-smart-do-search-region-or-symbol ()
   "Search in current directory using `dotspacemacs-search-tools'.
@@ -313,8 +313,8 @@ If DEFAULT-INPUTP is non nil then the current region or symbol at point
   (interactive)
   (call-interactively
    (spacemacs//helm-do-search-find-tool "helm-buffers-do"
-                                 dotspacemacs-search-tools
-                                 default-inputp)))
+                                        dotspacemacs-search-tools
+                                        default-inputp)))
 
 (defun spacemacs/helm-buffers-smart-do-search-region-or-symbol ()
   "Search in opened buffers using `dotspacemacs-search-tools' with
@@ -412,8 +412,8 @@ If DEFAULT-INPUTP is non nil then the current region or symbol at point
   (let ((projectile-require-project-root nil))
     (call-interactively
      (spacemacs//helm-do-search-find-tool "helm-project-do"
-                                   dotspacemacs-search-tools
-                                   default-inputp))))
+                                          dotspacemacs-search-tools
+                                          default-inputp))))
 
 (defun spacemacs/helm-project-smart-do-search-region-or-symbol ()
   "Search in current project using `dotspacemacs-search-tools' with
@@ -600,9 +600,9 @@ to buffers)."
   (with-current-buffer "*helm ag results*"
     (setq spacemacs--gne-min-line 5
           spacemacs--gne-max-line (save-excursion
-            (goto-char (point-max))
-            (previous-line)
-            (line-number-at-pos))
+                                    (goto-char (point-max))
+                                    (previous-line)
+                                    (line-number-at-pos))
           spacemacs--gne-line-func
           (lambda (c)
             (helm-ag--find-file-action
@@ -636,3 +636,12 @@ to buffers)."
   (interactive)
   (let ((helm-boring-buffer-regexp-list nil))
     (call-interactively #'helm-buffers-list)))
+
+;; Command search ---------------------------------------------------------------------
+
+(defun spacemacs/helm-M-x-fuzzy-matching ()
+  "Helm M-x with fuzzy matching enabled"
+  (interactive)
+  (let ((completion-styles completion-styles))
+    (add-to-list 'completion-styles `,(if (version< emacs-version "27") 'helm-flex 'flex) t)
+    (command-execute 'helm-M-x)))

layers/+completion/helm/packages.el

@@ -80,7 +80,7 @@
         (evil-ex-define-cmd "buffers" 'helm-buffers-list))
       ;; use helm by default for M-x, C-x C-f, and C-x b
       (unless (configuration-layer/layer-usedp 'smex)
-        (global-set-key (kbd "M-x") 'helm-M-x))
+        (global-set-key (kbd "M-x") 'spacemacs/helm-M-x-fuzzy-matching))
       (global-set-key (kbd "C-x C-f") 'spacemacs/helm-find-files)
       (global-set-key (kbd "C-x b") 'helm-buffers-list)
       ;; use helm everywhere
@@ -122,8 +122,8 @@
           (kbd "C-c C-e") 'spacemacs/helm-find-files-edit)
         (defun spacemacs//add-action-helm-find-files-edit ()
           (helm-add-action-to-source
-          "Edit files in dired `C-c C-e'" 'spacemacs//helm-find-files-edit
-          helm-source-find-files))
+           "Edit files in dired `C-c C-e'" 'spacemacs//helm-find-files-edit
+           helm-source-find-files))
         (add-hook 'helm-find-files-before-init-hook
                   'spacemacs//add-action-helm-find-files-edit))
       ;; Add minibuffer history with `helm-minibuffer-history'
@@ -151,7 +151,7 @@
                   ;; to overwrite any key binding
                   (unless (configuration-layer/layer-usedp 'smex)
                     (spacemacs/set-leader-keys
-                      dotspacemacs-emacs-command-key 'helm-M-x)))))
+                      dotspacemacs-emacs-command-key 'spacemacs/helm-M-x-fuzzy-matching)))))
     :config
     (progn
       (helm-mode)

layers/+misc/multiple-cursors/packages.el

@@ -57,7 +57,7 @@
         "smst" 'mc/reverse-regions)
       (setq mc/always-run-for-all t)
       (with-eval-after-load 'multiple-cursors-core
-        (add-to-list 'mc/cmds-to-run-once 'helm-M-x)
+        (add-to-list 'mc/cmds-to-run-once 'spacemacs/helm-M-x-fuzzy-matching)
         (add-to-list 'mc/cmds-to-run-once 'counsel-M-x)
         (add-to-list 'mc/cmds-to-run-once 'spacemacs/default-pop-shell)
         ))))