Make the bufnr argument have similar semantics across API functions;
namely, a nil value means "all buffers" while 0 means "current buffer".
This increases the flexibility of the API by allowing functions such as
enable() and disable() to apply globally or per-namespace, rather than
only on a specific buffer.
Also fix a few other small bugs regarding saving and restoring extmarks.
In particular, now that the virtual text and underline handlers have
their own dedicated namespaces, they should be responsible for saving
and restoring their own extmarks. Also fix the wrong argument ordering
in the call to `clear_diagnostic_cache` in the `on_detach` callback.
Rather than treating virtual_text, signs, and underline specially,
introduce the concept of generic "handlers", of which those three are
simply the defaults bundled with Nvim. Handlers are called in
`vim.diagnostic.show()` and `vim.diagnostic.hide()` and are used to
handle how diagnostics are displayed.
'show_line_diagnostics()' and 'show_position_diagnostics()' are
almost identical; they differ only in the fact that the latter also
accepts a column to form a full position, rather than just a line. This
is not enough to justify two separate interfaces for this common
functionality.
Renaming this to simply 'show_diagnostics()' is one step forward, but
that is also not a good name as the '_diagnostics()' suffix is
redundant. However, we cannot name it simply 'show()' since that
function already exists with entirely different semantics.
Instead, combine these two into a single 'open_float()' function that
handles all of the cases of showing diagnostics in a floating window.
Also add a "float" key to 'vim.diagnostic.config()' to provide global
values of configuration options that can be overridden ephemerally.
This makes the float API consistent with the rest of the diagnostic API.
BREAKING CHANGE
When using `true` as the value of a configuration option, the option is
configured to use default values. For example, if a user configures
virtual text to include the source globally (using
vim.diagnostic.config) and a specific namespace or producer configures
virtual text with `virt_text = true`, the user's global configuration is
overriden.
Instead, interpret a value of `true` to mean "use existing settings if
defined, otherwise use defaults".
Rather than relying on the order in which signs are placed to dictate
the order in which they are displayed, explicitly set the priority of
the sign according to the severity of the diagnostic and the value of
severity_sort. If severity_sort is false or unset then all signs use the
same priority.
This function isn't compatible with including diagnostic sources when
"source" is "if_many" since it only has access to diagnostics for a
single line. Rather than having an inconsistent or incomplete interface,
make this function private. It is still exported as part of the module
for backward compatibility with vim.lsp.diagnostics, but it can
eventually be made into a local function.
* feat(diagnostic): add vim.diagnostic.match()
Provide vim.diagnostic.match() to generate a diagnostic from a string and
a Lua pattern.
* feat(diagnostic): add tolist() and fromlist()
When severity_sort is true, higher severities should be displayed before
lower severities (e.g. ERROR is displayed over WARN).
Also improved the test case for this.
This generalizes diagnostic handling outside of just the scope of LSP.
LSP clients are now a specific case of a diagnostic producer, but the
diagnostic subsystem is decoupled from the LSP subsystem (or will be,
eventually).
More discussion at [1].
[1]: https://github.com/neovim/neovim/pull/15585
