Check for the existence of zig in PATH in main()

src/main.zig

@@ -888,6 +888,37 @@ pub fn main() anyerror!void {
         }
     }
 
+    // Find the zig executable in PATH
+    var has_zig = false;
+
+    find_zig: {
+        const env_path = std.process.getEnvVarOwned(allocator, "PATH") catch |err| switch (err) {
+            error.EnvironmentVariableNotFound => {
+                std.debug.warn("Could not get PATH.\n", .{});
+                break :find_zig;
+            },
+            else => return err,
+        };
+        defer allocator.free(env_path);
+
+        var it = std.mem.tokenize(env_path,&[_]u8{std.fs.path.delimiter});
+        const exe_extension = @as(std.zig.CrossTarget, .{}).exeFileExt();
+        const zig_exe = try std.fmt.allocPrint(allocator, "zig{}", .{exe_extension});
+        defer allocator.free(zig_exe);
+
+        while (it.next()) |path| {
+            const full_path = try std.fs.path.join(allocator, &[_][]const u8{
+                path,
+                zig_exe,
+            });
+            var buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;
+            const zig_path = std.os.realpath(full_path, &buf) catch continue;
+            std.debug.warn("Found zig in PATH: {}\n", .{zig_path});
+            has_zig = true;
+            break :find_zig;
+        }
+    }
+
     try document_store.init(allocator);
     defer document_store.deinit();