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145 lines
4.6 KiB
145 lines
4.6 KiB
.. _flycheck-syntax-checks:
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===============
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Check buffers
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===============
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Flycheck provides two Emacs minor modes for automatic syntax checking:
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:mode:`flycheck` to enable syntax checking in the current buffer, and
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:mode:`global-flycheck` to enable syntax checking in all buffers whenever
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possible.
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.. minor-mode:: flycheck-mode
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Enable :ref:`automatic syntax checking <flycheck-automatic-checks>` in the
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current buffer.
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.. minor-mode:: global-flycheck-mode
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Enable :mode:`flycheck` in all buffers where syntax checking is possible.
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.. note::
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This mode does not enable :mode:`flycheck` in remote files (via
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TRAMP) and encrypted files. Checking remote files may be very slow
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depending on the network connections, and checking encrypted files would
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leak confidential data to temporary files and subprocesses.
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You can manually enable :mode:`flycheck` in these buffers nonetheless, but
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we do *not* recommend this for said reasons.
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Add the following to your :term:`init file` to enable syntax checking
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permanently:
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.. code-block:: elisp
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(add-hook 'after-init-hook #'global-flycheck-mode)
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You can exclude specific major modes from syntax checking with
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`flycheck-global-modes`:
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.. defcustom:: flycheck-global-modes
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Major modes for which :mode:`global-flycheck` turns on :mode:`flycheck`:
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``t`` (the default)
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Turn :mode:`flycheck` on for all major modes.
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:samp:`({foo-mode} …)`
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Turn :mode:`flycheck` on for all major modes in this list,
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i.e. whenever the value of ``major-mode`` is contained in this list.
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:samp:`(not {foo-mode} …)`
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Turn :mode:`flycheck` on for all major nodes *not* in this list,
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i.e. whenever the value of ``major-mode`` is *not* contained in this
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list.
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.. note::
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:mode:`global-flycheck` never turns on :mode:`flycheck` in major modes
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whose ``mode-class`` property is ``special``, regardless of the value
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of this option. Syntax checking simply makes no sense in special
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buffers which are typically intended for non-interactive display rather
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than editing.
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.. seealso::
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:infonode:`(elisp)Major Mode Conventions`
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Information about major modes, and modes marked as special.
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.. _flycheck-automatic-checks:
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Check automatically
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===================
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By default :mode:`flycheck` automatically checks a buffer whenever
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* it is enabled,
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* the buffer is saved,
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* a new line is inserted,
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* or a short time after the last change was made in a buffer.
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You can customise this behaviour with `flycheck-check-syntax-automatically`:
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.. defcustom:: flycheck-check-syntax-automatically
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A list of events which trigger a syntax check in the current buffer:
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``save``
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Check the buffer immediately after it was saved.
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``new-line``
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Check the buffer immediately after a new line was inserted.
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``idle-change``
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Check the buffer a short time after the last change. The delay is
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customisable with `flycheck-idle-change-delay`:
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.. defcustom:: flycheck-idle-change-delay
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Seconds to wait after the last change to the buffer before starting a
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syntax check.
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``idle-buffer-switch``
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Check the buffer a short time after switching to it from another
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buffer. The delay is customisable with
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`flycheck-idle-buffer-switch-delay`:
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.. defcustom:: flycheck-idle-buffer-switch-delay
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Seconds to wait after switching to a buffer before starting a
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syntax check.
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If you switch to several buffers in rapid succession, the
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behavior depends on
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`flycheck-buffer-switch-check-intermediate-buffers`:
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.. defcustom:: flycheck-buffer-switch-check-intermediate-buffers
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If non-nil, then a buffer you switch to will have a syntax
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check run even if you switch to another buffer before it
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starts. If nil, then only the current buffer can have a
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syntax check run. Note that syntax checks can still be run
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in other buffers due to changes to their contents.
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``mode-enabled``
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Check the buffer immediately after :mode:`flycheck` was enabled.
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For instance with the following setting :mode:`flycheck` will only check the
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buffer when it was saved:
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.. code-block:: elisp
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(setq flycheck-check-syntax-automatically '(mode-enabled save))
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.. _flycheck-manual-checks:
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Check manually
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==============
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You can also start a syntax check explicitly with `C-c ! c`:
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.. define-key:: C-c ! c
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M-x flycheck-buffer
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Check syntax in the current buffer.
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