add a default option for import(builtin)

build.zig

@@ -1,5 +1,5 @@
 const std = @import("std");
-const builtin = std.builtin;
+const builtin = @import("builtin");
 const shared = @import("./src/shared.zig");
 
 pub fn build(b: *std.build.Builder) !void {

src/Config.zig

@@ -35,3 +35,5 @@ max_detail_length: usize = 1024 * 1024,
 /// Skips references to std. This will improve lookup speeds.
 /// Going to definition however will continue to work
 skip_std_references: bool = false,
+
+builtin_path: ?[]const u8 = null,

src/DocumentStore.zig

@@ -54,6 +54,7 @@ build_runner_cache_path: []const u8,
 std_uri: ?[]const u8,
 zig_cache_root: []const u8,
 zig_global_cache_root: []const u8,
+builtin_path: ?[]const u8,
 
 pub fn init(
     self: *DocumentStore,
@@ -64,6 +65,7 @@ pub fn init(
     zig_lib_path: ?[]const u8,
     zig_cache_root: []const u8,
     zig_global_cache_root: []const u8,
+    builtin_path: ?[]const u8,
 ) !void {
     self.allocator = allocator;
     self.handles = std.StringHashMap(*Handle).init(allocator);
@@ -74,6 +76,7 @@ pub fn init(
     self.std_uri = try stdUriFromLibPath(allocator, zig_lib_path);
     self.zig_cache_root = zig_cache_root;
     self.zig_global_cache_root = zig_global_cache_root;
+    self.builtin_path = builtin_path;
 }
 
 fn loadBuildAssociatedConfiguration(allocator: std.mem.Allocator, build_file: *BuildFile, build_file_path: []const u8) !void {
@@ -239,6 +242,12 @@ fn newDocument(self: *DocumentStore, uri: []const u8, text: [:0]u8) anyerror!*Ha
         loadBuildAssociatedConfiguration(self.allocator, build_file, build_file_path) catch |err| {
             log.debug("Failed to load config associated with build file {s} (error: {})", .{ build_file.uri, err });
         };
+        if (build_file.builtin_uri == null) {
+            if (self.builtin_path != null) {
+                build_file.builtin_uri = try URI.fromPath(self.allocator, self.builtin_path.?);
+                log.info("builtin config not found, falling back to defualt: {s}", .{build_file.builtin_uri});
+            }
+        }
 
         // TODO: Do this in a separate thread?
         // It can take quite long.
@@ -605,7 +614,7 @@ pub fn uriFromImportStr(self: *DocumentStore, allocator: std.mem.Allocator, hand
                 return try allocator.dupe(u8, builtin_uri);
             }
         }
-        return null; // TODO find the correct zig-cache folder
+        return try allocator.dupe(u8, self.builtin_path.?);
     } else if (!std.mem.endsWith(u8, import_str, ".zig")) {
         if (handle.associated_build_file) |build_file| {
             for (build_file.packages.items) |pkg| {

src/main.zig

@@ -1128,7 +1128,7 @@ fn loadConfigFile(file_path: []const u8) ?Config {
 
     const file_buf = file.readToEndAlloc(allocator, 0x1000000) catch return null;
     defer allocator.free(file_buf);
-    @setEvalBranchQuota(2000);
+    @setEvalBranchQuota(3000);
     // TODO: Better errors? Doesn't seem like std.json can provide us positions or context.
     var config = std.json.parse(Config, &std.json.TokenStream.init(file_buf), std.json.ParseOptions{ .allocator = allocator }) catch |err| {
         logger.warn("Error while parsing configuration file: {}", .{err});
@@ -1708,14 +1708,14 @@ pub fn main() anyerror!void {
             std.debug.print("Falling back to a lookup in the local and global configuration folders\n", .{});
         }
         if (try known_folders.getPath(allocator, .local_configuration)) |path| {
-            defer allocator.free(path);
+            config_path = path;
             if (loadConfigInFolder(path)) |conf| {
                 config = conf;
                 break :config_read;
             }
         }
         if (try known_folders.getPath(allocator, .global_configuration)) |path| {
-            defer allocator.free(path);
+            config_path = path;
             if (loadConfigInFolder(path)) |conf| {
                 config = conf;
                 break :config_read;
@@ -1789,6 +1789,30 @@ pub fn main() anyerror!void {
         logger.warn("Zig standard library path not specified in zls.json and could not be resolved from the zig executable", .{});
     }
 
+    if (config.builtin_path == null and config.zig_exe_path != null and config_path != null) {
+        const result = try std.ChildProcess.exec(.{
+            .allocator = allocator,
+            .argv = &.{
+                config.zig_exe_path.?,
+                "build-exe",
+                "--show-builtin",
+            },
+            .max_output_bytes = 1024 * 1024 * 50,
+        });
+        defer allocator.free(result.stdout);
+        defer allocator.free(result.stderr);
+
+        var d = try std.fs.cwd().openDir(config_path.?, .{});
+        defer d.close();
+
+        const f = try d.createFile("builtin.zig", .{});
+        defer f.close();
+
+        try f.writer().writeAll(result.stdout);
+
+        config.builtin_path = try std.fs.path.join(allocator, &.{ config_path.?, "builtin.zig" });
+    }
+
     const build_runner_path = if (config.build_runner_path) |p|
         try allocator.dupe(u8, p)
     else blk: {
@@ -1821,6 +1845,7 @@ pub fn main() anyerror!void {
         // Since we don't compile anything and no packages should put their
         // files there this path can be ignored
         "ZLS_DONT_CARE",
+        config.builtin_path,
     );
     defer document_store.deinit();