improve behavior if zig_exe_path is not set (#830)

src/DocumentStore.zig

@@ -858,10 +858,7 @@ pub fn resolveCImport(self: *DocumentStore, handle: Handle, node: Ast.Node.Index
 /// caller owns the returned memory
 pub fn uriFromImportStr(self: *const DocumentStore, allocator: std.mem.Allocator, handle: Handle, import_str: []const u8) error{OutOfMemory}!?Uri {
     if (std.mem.eql(u8, import_str, "std")) {
-        const zig_lib_path = self.config.zig_lib_path orelse {
+        const zig_lib_path = self.config.zig_lib_path orelse return null;
-            log.debug("Cannot resolve std library import, path is null.", .{});
-            return null;
-        };
 
         const std_path = std.fs.path.resolve(allocator, &[_][]const u8{ zig_lib_path, "./std/std.zig" }) catch |err| switch (err) {
             error.OutOfMemory => return error.OutOfMemory,

src/Server.zig

@@ -1683,17 +1683,30 @@ fn initializeHandler(server: *Server, writer: anytype, id: types.RequestId, req:
     log.info("{}", .{server.client_capabilities});
     log.info("Using offset encoding: {s}", .{std.meta.tagName(server.offset_encoding)});
 
+    if (server.config.zig_exe_path) |exe_path| blk: {
         // TODO avoid having to call getZigEnv twice
         // once in init and here
-    const env = configuration.getZigEnv(server.allocator, server.config.zig_exe_path.?) orelse return;
+        const env = configuration.getZigEnv(server.allocator, exe_path) orelse break :blk;
         defer std.json.parseFree(configuration.Env, env, .{ .allocator = server.allocator });
 
-    const zig_exe_version = std.SemanticVersion.parse(env.version) catch return;
+        const zig_exe_version = std.SemanticVersion.parse(env.version) catch break :blk;
 
         if (zig_builtin.zig_version.order(zig_exe_version) == .gt) {
-        const version_mismatch_message = try std.fmt.allocPrint(server.arena.allocator(), "ZLS was built with Zig {}, but your Zig version is {s}. Update Zig to avoid unexpected behavior.", .{ zig_builtin.zig_version, env.version });
+            const version_mismatch_message = try std.fmt.allocPrint(
+                server.arena.allocator(),
+                "ZLS was built with Zig {}, but your Zig version is {s}. Update Zig to avoid unexpected behavior.",
+                .{ zig_builtin.zig_version, env.version },
+            );
             try server.showMessage(writer, .Warning, version_mismatch_message);
         }
+    } else {
+        try server.showMessage(
+            writer,
+            .Warning,
+            \\ZLS failed to find Zig. Please add Zig to your PATH or set the zig_exe_path config option in your zls.json.
+            ,
+        );
+    }
 }
 
 fn initializedHandler(server: *Server, writer: anytype, id: types.RequestId) !void {

src/translate_c.zig

@@ -162,11 +162,11 @@ pub fn translate(allocator: std.mem.Allocator, config: Config, include_dirs: []c
     };
 
     const base_args = &[_][]const u8{
-        config.zig_exe_path.?,
+        config.zig_exe_path orelse return null,
         "translate-c",
         "--enable-cache",
         "--zig-lib-dir",
-        config.zig_lib_path.?,
+        config.zig_lib_path orelse return null,
         "--cache-dir",
         config.global_cache_path.?,
         "-lc",