feat(lsp): configurable diagnostic severity (#1325)

* feat(lsp): configurable diagnostic severity

Allow severity of diagnostic messages to be configured.
E.g. allow turning of Hint level diagnostics.

Fixes: https://github.com/helix-editor/helix/issues/1007

* Use language_config() method

* Add documentation for diagnostic_severity

* Use unreachable for unknown severity level

* fix: documentation for diagnostic_severity config

3 files changed, 16 insertions, 4 deletions

diff --git a/helix-core/src/diagnostic.rs b/helix-core/src/diagnostic.rs
index 4fcf51c9..210ad639 100644
--- a/helix-core/src/diagnostic.rs
+++ b/helix-core/src/diagnostic.rs
@@ -1,12 +1,19 @@
 //! LSP diagnostic utility types.
+use serde::{Deserialize, Serialize};
 
 /// Describes the severity level of a [`Diagnostic`].
-#[derive(Debug, Clone, Copy, Eq, PartialEq)]
+#[derive(Debug, Clone, Copy, Eq, PartialEq, PartialOrd, Ord, Deserialize, Serialize)]
 pub enum Severity {
-    Error,
-    Warning,
-    Info,
     Hint,
+    Info,
+    Warning,
+    Error,
+}
+
+impl Default for Severity {
+    fn default() -> Self {
+        Self::Hint
+    }
 }
 
 /// A range of `char`s within the text.
diff --git a/helix-core/src/indent.rs b/helix-core/src/indent.rs
index b6f5081a..c2baf3cc 100644
--- a/helix-core/src/indent.rs
+++ b/helix-core/src/indent.rs
@@ -442,6 +442,7 @@ where
         );
 
         let doc = Rope::from(doc);
+        use crate::diagnostic::Severity;
         use crate::syntax::{
             Configuration, IndentationConfiguration, LanguageConfiguration, Loader,
         };
@@ -459,6 +460,7 @@ where
                 roots: vec![],
                 comment_token: None,
                 auto_format: false,
+                diagnostic_severity: Severity::Warning,
                 language_server: None,
                 indent: Some(IndentationConfiguration {
                     tab_width: 4,
diff --git a/helix-core/src/syntax.rs b/helix-core/src/syntax.rs
index ef35fc75..cdae0210 100644
--- a/helix-core/src/syntax.rs
+++ b/helix-core/src/syntax.rs
@@ -1,5 +1,6 @@
 use crate::{
     chars::char_is_line_ending,
+    diagnostic::Severity,
     regex::Regex,
     transaction::{ChangeSet, Operation},
     Rope, RopeSlice, Tendril,
@@ -63,6 +64,8 @@ pub struct LanguageConfiguration {
 
     #[serde(default)]
     pub auto_format: bool,
+    #[serde(default)]
+    pub diagnostic_severity: Severity,
 
     // content_regex
     #[serde(default, skip_serializing, deserialize_with = "deserialize_regex")]