show c source when hovering over cImport

src/Server.zig

@@ -1067,25 +1067,48 @@ fn hoverDefinitionBuiltin(server: *Server, pos_index: usize, handle: *const Docu
     const name = identifierFromPosition(pos_index, handle.*);
     if (name.len == 0) return null;
 
-    for (data.builtins) |builtin| {
+    const builtin = for (data.builtins) |builtin| {
         if (std.mem.eql(u8, builtin.name[1..], name)) {
+            break builtin;
+        }
+    } else return null;
+
+    var contents: std.ArrayListUnmanaged(u8) = .{};
+    var writer = contents.writer(server.arena.allocator());
+
+    if (std.mem.eql(u8, name, "cImport")) blk: {
+        const index = for (handle.cimports.items(.node)) |cimport_node, index| {
+            const main_token = handle.tree.nodes.items(.main_token)[cimport_node];
+            const cimport_loc = offsets.tokenToLoc(handle.tree, main_token);
+            if (cimport_loc.start <= pos_index and pos_index <= cimport_loc.end) break index;
+        } else break :blk;
+
+        const source = handle.cimports.items(.source)[index];
+
+        try writer.print(
+            \\```c
+            \\{s}
+            \\```
+            \\
+        , .{source});
+    }
+
+    try writer.print(
+        \\```zig
+        \\{s}
+        \\```
+        \\{s}
+    , .{ builtin.signature, builtin.documentation });
+
     return types.Hover{
         .contents = .{
             .MarkupContent = .{
                 .kind = .markdown,
-                        .value = try std.fmt.allocPrint(
+                .value = contents.items,
-                            server.arena.allocator(),
-                            "```zig\n{s}\n```\n{s}",
-                            .{ builtin.signature, builtin.documentation },
-                        ),
             },
         },
     };
 }
-    }
-
-    return null;
-}
 
 fn hoverDefinitionGlobal(server: *Server, pos_index: usize, handle: *const DocumentStore.Handle) error{OutOfMemory}!?types.Hover {
     const tracy_zone = tracy.trace(@src());