Default `#[schemars(deny_unknown_fields)] for json-language-server schemas (#33883)

Followup to #33678, doing the same thing for all JSON Schema files
provided to json-language-server

Release Notes:

* Added warnings for unknown fields when editing `tasks.json` /
`snippets.json`.

crates/util/Cargo.toml

@@ -30,6 +30,7 @@ log.workspace = true
 rand = { workspace = true, optional = true }
 regex.workspace = true
 rust-embed.workspace = true
+schemars.workspace = true
 serde.workspace = true
 serde_json.workspace = true
 serde_json_lenient.workspace = true

crates/util/src/schemars.rs

@@ -0,0 +1,58 @@
+use schemars::{JsonSchema, transform::transform_subschemas};
+
+const DEFS_PATH: &str = "#/$defs/";
+
+/// Replaces the JSON schema definition for some type if it is in use (in the definitions list), and
+/// returns a reference to it.
+///
+/// This asserts that JsonSchema::schema_name() + "2" does not exist because this indicates that
+/// there are multiple types that use this name, and unfortunately schemars APIs do not support
+/// resolving this ambiguity - see https://github.com/GREsau/schemars/issues/449
+///
+/// This takes a closure for `schema` because some settings types are not available on the remote
+/// server, and so will crash when attempting to access e.g. GlobalThemeRegistry.
+pub fn replace_subschema<T: JsonSchema>(
+    generator: &mut schemars::SchemaGenerator,
+    schema: impl Fn() -> schemars::Schema,
+) -> schemars::Schema {
+    // fallback on just using the schema name, which could collide.
+    let schema_name = T::schema_name();
+    let definitions = generator.definitions_mut();
+    assert!(!definitions.contains_key(&format!("{schema_name}2")));
+    if definitions.contains_key(schema_name.as_ref()) {
+        definitions.insert(schema_name.to_string(), schema().to_value());
+    }
+    schemars::Schema::new_ref(format!("{DEFS_PATH}{schema_name}"))
+}
+
+/// Adds a new JSON schema definition and returns a reference to it. **Panics** if the name is
+/// already in use.
+pub fn add_new_subschema(
+    generator: &mut schemars::SchemaGenerator,
+    name: &str,
+    schema: serde_json::Value,
+) -> schemars::Schema {
+    let old_definition = generator.definitions_mut().insert(name.to_string(), schema);
+    assert_eq!(old_definition, None);
+    schemars::Schema::new_ref(format!("{DEFS_PATH}{name}"))
+}
+
+/// Defaults `additionalProperties` to `true`, as if `#[schemars(deny_unknown_fields)]` was on every
+/// struct. Skips structs that have `additionalProperties` set (such as if #[serde(flatten)] is used
+/// on a map).
+#[derive(Clone)]
+pub struct DefaultDenyUnknownFields;
+
+impl schemars::transform::Transform for DefaultDenyUnknownFields {
+    fn transform(&mut self, schema: &mut schemars::Schema) {
+        if let Some(object) = schema.as_object_mut() {
+            if object.contains_key("properties")
+                && !object.contains_key("additionalProperties")
+                && !object.contains_key("unevaluatedProperties")
+            {
+                object.insert("additionalProperties".to_string(), false.into());
+            }
+        }
+        transform_subschemas(self, schema);
+    }
+}

crates/util/src/util.rs

@@ -5,6 +5,7 @@ pub mod fs;
 pub mod markdown;
 pub mod paths;
 pub mod redact;
+pub mod schemars;
 pub mod serde;
 pub mod shell_env;
 pub mod size;