fix: add bitflags module to embedded wit_bindgen runtime

Add bitflags module to the embedded runtime in rust_wasm_component_bindgen.bzl
to support WASI filesystem interfaces that generate bitflags for DescriptorFlags,
PathFlags, and OpenFlags.

Changes:
- Add pub mod bitflags with pub(crate) use bitflags in both guest and native-guest wrappers
- Add bitflags dependency to both bindings libraries
- Add bitflags crate to tools/checksum_updater Cargo.toml

The bitflags macro is now accessible as crate::wit_bindgen::rt::bitflags::bitflags!
as expected by generated code.

Tested with:
- //examples/basic:hello_component_bindings_host
- //tools/checksum_updater_wasm:checksum_updater_wasm_component (uses wasi:filesystem/types)

Author: avrabe

MODULE.bazel.lock

@@ -157,6 +157,13 @@ pub mod wit_bindgen {
                 }
             }
         }
+
+        // Bitflags module for WASI interfaces
+        pub mod bitflags {
+            // Re-export bitflags macro without #[macro_export]
+            // Generated code expects: crate::wit_bindgen::rt::bitflags::bitflags!
+            pub(crate) use bitflags;
+        }
     }
 }
 
@@ -244,6 +251,13 @@ pub mod wit_bindgen {
                 }
             }
         }
+
+        // Bitflags module for WASI interfaces
+        pub mod bitflags {
+            // Re-export bitflags macro without #[macro_export]
+            // Generated code expects: crate::wit_bindgen::rt::bitflags::bitflags!
+            pub(crate) use bitflags;
+        }
     }
 }
 
@@ -498,6 +512,7 @@ def rust_wasm_component_bindgen(
         srcs = [":" + wrapper_native_guest_target],
         crate_name = name.replace("-", "_") + "_bindings",
         edition = "2021",
+        deps = ["@crates//:bitflags"],  # Required for WASI filesystem interfaces
         visibility = visibility,  # Make native bindings publicly available
     )
 
@@ -508,6 +523,7 @@ def rust_wasm_component_bindgen(
         srcs = [":" + wrapper_guest_target],
         crate_name = name.replace("-", "_") + "_bindings",
         edition = "2021",
+        deps = ["@crates//:bitflags"],  # Required for WASI filesystem interfaces
         visibility = ["//visibility:private"],
     )
 

rust/rust_wasm_component_bindgen.bzl

@@ -33,6 +33,7 @@ tempfile = "3.23"
 async-trait = "0.1"
 wit-bindgen = "0.46.0"  # WIT binding generation for macro usage (MUST match CLI version in wasm_toolchain.bzl)
 uuid = { version = "1.18", default-features = false }  # UUID generation for user service (deterministic, no getrandom dependency)
+bitflags = "2.6"  # Bitflags for WASI filesystem interfaces in generated bindings
 
 [dev-dependencies]
 tokio-test = "0.4"