Tweak builtins and hint user about missing docs

crates/builtin/build.rs

@@ -68,13 +68,14 @@ fn main() {
             "true" | "false" | "null" => "Const",
             _ => "Function",
         };
-        let summary = builtins_dump
+        let args = builtins_dump
             .get(name)
             .map(|b @ DumpBuiltin { args, arity, .. }| {
                 assert_eq!(args.len(), *arity, "Arity mismatch: {b:?}");
-                let args = args.iter().flat_map(|arg| [" ", arg]).collect::<String>();
-                format!("builtins.{name}{args}")
-            });
+                args.iter().flat_map(|arg| [" ", arg]).collect::<String>()
+            })
+            .unwrap_or_default();
+        let summary = format!("`builtins.{name}{args}`");
         let doc = builtins_dump.get(name).map(|b| &b.doc);
         phf_gen.entry(name, &format!("crate::Builtin {{ kind: crate::BuiltinKind::{kind}, is_global: {is_global}, summary: {summary:?}, doc: {doc:?} }}"));
     }

crates/builtin/src/lib.rs

@@ -2,7 +2,7 @@
 pub struct Builtin {
     pub kind: BuiltinKind,
     pub is_global: bool,
-    pub summary: Option<&'static str>,
+    pub summary: &'static str,
     pub doc: Option<&'static str>,
 }
 
@@ -27,7 +27,7 @@ mod tests {
             Builtin {
                 kind: BuiltinKind::Const,
                 is_global: true,
-                summary: None,
+                summary: "`builtins.true`",
                 doc: None,
             },
         );
@@ -37,7 +37,7 @@ mod tests {
             Builtin {
                 kind: BuiltinKind::Function,
                 is_global: false,
-                summary: Some("builtins.attrNames set"),
+                summary: "`builtins.attrNames set`",
                 doc: Some(
                     "\
 Return the names of the attributes in the set *set* in an

crates/ide/src/ide/completion.rs

@@ -177,7 +177,7 @@ fn complete_expr(
             source_range,
             replace: name.into(),
             kind: b.kind.into(),
-            brief: b.summary.map(|s| s.to_owned()),
+            brief: Some(b.summary.into()),
             doc: b.doc.map(|s| s.to_owned()),
         })
         .for_each(&mut feed);

crates/ide/src/ide/hover.rs

@@ -42,14 +42,11 @@ pub(crate) fn hover(
             None => {}
             Some(ResolveResult::Builtin(name)) => {
                 let b = &ALL_BUILTINS[*name];
-                let mut markup = String::new();
-                match b.summary {
-                    None => writeln!(markup, "`builtins.{name}`").unwrap(),
-                    Some(summary) => writeln!(markup, "`{summary}`").unwrap(),
-                }
-                if let Some(doc) = b.doc {
-                    writeln!(markup, "\n{doc}").unwrap();
-                }
+                let markup = format!(
+                    "{}\n\n{}",
+                    b.summary,
+                    b.doc.unwrap_or("(No documentation from Nix)"),
+                );
                 return Some(HoverResult { range, markup });
             }
             Some(ResolveResult::WithExprs(withs)) => {
@@ -166,7 +163,15 @@ mod tests {
 
     #[test]
     fn builtin() {
-        check("$0true", "true", expect!["`builtins.true`"]);
+        check(
+            "$0true",
+            "true",
+            expect![[r#"
+                `builtins.true`
+
+                (No documentation from Nix)
+            "#]],
+        );
         check(
             "$0map",
             "map",