Add +tools/cquery layer

[MaskRay]

tl;dr https://github.com/cquery-project/cquery/wiki/Emacs
https://www.reddit.com/r/emacs/comments/806mgw/recent_improvement_of_cquery_and_emacscquery/

cquery is a low-latency language server supporting multi-million line C++ code-bases, powered by libclang.

Since current c-c++ layer needs cleanup and I am not an experienced elisp or spacemacs user, I decide to put it into +tools/ instead of +lang/c-c++/. Another reason doing this is that cquery also supports Objective-C as libclang supports it, though probably with many issues because of the lack of Objective-C users 😜 Anyway, I hope more experienced user can move it into +lang/c-c++ or elsewhere that is appropriate.

+tools/cquery depends on +tools/lsp, which is added in another PR #10211

[Jackson-soft]

good!!

[MaskRay]

With this PR, basic features work fine:

• xref-find-definitions and xref-find-references
• document symbol highlight
• completion-at-point
• company-lsp

Some tricky parts. cquery saves a copy of indexed source files (so that it can serve requests when the index is out-of-sync with the source file in editing) in .cquery_cached_index (relative to the project root by default) and these files may be listed by projectile, which is certainly undesired.

Adding the cache directory to projectile-globally-ignored-directories works but if the user customizes cquery-cache-dir, the logic blacklist directory should be changed accordingly.

    (require 'projectile)
    (add-to-list 'projectile-globally-ignored-directories ".cquery_cached_index")

cquery users usually do not use ycmd for completion. However, ycmd is enabled by default in +lang/c-c++/packages.el. I personally use dotspacemacs-excluded-packages '(cmake-ide info+ racer ycmd)

(cquery-use-default-rainbow-sem-highlight) is nice but I do not enable it in this PR because for larger source file the overlay rendering in Emacs may be very slow.

Here is my personal layer https://github.com/MaskRay/Config/blob/master/home/.emacs.d/private/%2Bmy/cquery/packages.el

Some shortcuts are really nice but I do not know where I should bind them.

    (dolist (mode '("c" "c++" "go" "haskell" "javascript" "python" "rust"))
      (let ((handler (intern (format "spacemacs-jump-handlers-%s-mode" mode))))
        (add-to-list handler 'lsp-ui-peek-find-definitions))
      (let ((handler (intern (format "spacemacs-reference-handlers-%s-mode" mode))))
        (add-to-list handler 'lsp-ui-peek-find-references)))

    (defun cquery/base () (interactive) (lsp-ui-peek-find-custom 'base "$cquery/base"))
    (defun cquery/callers () (interactive) (lsp-ui-peek-find-custom 'callers "$cquery/callers"))
    (defun cquery/derived () (interactive) (lsp-ui-peek-find-custom 'derived "$cquery/derived"))
    (defun cquery/vars () (interactive) (lsp-ui-peek-find-custom 'vars "$cquery/vars"))
    (defun cquery/random () (interactive) (lsp-ui-peek-find-custom 'random "$cquery/random"))

    (spacemacs/set-leader-keys-for-minor-mode 'lsp-mode
      "la" #'lsp-ui-find-workspace-symbol
      "lA" #'lsp-ui-peek-find-workspace-symbol
      "lf" #'lsp-format-buffer
      "ll" #'lsp-ui-sideline-mode
      "lD" #'lsp-ui-doc-mode
      "ln" #'lsp-ui-find-next-reference
      "lp" #'lsp-ui-find-previous-reference
      "lr" #'lsp-rename
      )

    (dolist (mode c-c++-modes)
      (spacemacs/set-leader-keys-for-major-mode mode
        "lb" #'cquery/base
        "lc" #'cquery/callers
        "ld" #'cquery/derived
        "lR" #'cquery-freshen-index
        "lv" #'cquery/vars
        "l SPC" #'cquery/random
       ))

[sdwolfz]

How does cquery behave when the .cquery_cached_index directory is located in the project directory and you execute git clean -fdx? Does it know to rebuild it or does it glitch out / crash?

[MaskRay]

How does cquery behave when the .cquery_cached_index directory is located in the project directory and you execute git clean -fdx? Does it know to rebuild it or does it glitch out / crash?

@jacobdufault to answer this question.

[MaskRay]

I hope someone could pick this up and make +lang/c-c++ layer accept cquery as a backend.

[iromise]

Hope it can be integrated in spacemacs soon.

[cormacc]

Reworked some of MaskRay's config into a a new PR for the lsp layer, here:
#10486

And an attempt at a cquery layer here:
cormacc@b8ae1bc

I'll raise a new PR for the cquery layer if the lsp-layer one gets merged (it builds on it).