Don't emit empty namespaces.

bazel/llvm.bzl

@@ -53,7 +53,7 @@ def _llvm_loader_repository(repository_ctx):
             executable = False,
         )
 
-LLVM_COMMIT_SHA = "5a403150b468a5de7ddf9f1e295643c9c518aee8"
+LLVM_COMMIT_SHA = "9a0b003dde83d46f2ed6d95d85d1d9de3c1fe908"
 
 def llvm_loader_repository_dependencies():
     # This *declares* the dependency, but it won't actually be *downloaded* unless it's used.

cc_bindings_from_rs/generate_bindings/lib.rs

@@ -367,6 +367,9 @@ fn format_with_cc_body(
     mut tokens: TokenStream,
     attributes: Vec<TokenStream>,
 ) -> Result<TokenStream> {
+    if tokens.is_empty() {
+        return Ok(quote! {});
+    }
     let mut namespaces = ns.parts().map(|s| format_cc_ident(db, s)).collect::<Result<Vec<_>>>()?;
 
     // Nested namespace syntax does not accept attributes (see b/445613694), so we have to split out

cc_bindings_from_rs/test/enums/cpp_enums_cc_api.h

@@ -83,12 +83,6 @@ enum class CRUBIT_INTERNAL_RUST_TYPE(
 
 }  // namespace cpp_enums::forward_declared_enum
 
-namespace cpp_enums::classless_enum {}
-
-namespace cpp_enums::cpp_enum {}
-
-namespace cpp_enums::deprecated_enum {}
-
 namespace cpp_enums::forward_declared_enum {
 
 namespace __crubit_internal {

cc_bindings_from_rs/test/golden/type_aliases_cc_api.h

@@ -48,8 +48,6 @@ std::int32_t func_using_alias();
 
 }  // namespace type_aliases_rust::test_type_aliases
 
-namespace type_aliases_rust::test_deprecated_type_alias {}
-
 namespace type_aliases_rust::test_type_aliases {
 
 namespace __crubit_internal {

cc_bindings_from_rs/test/modules/modules_cc_api.h

@@ -183,17 +183,5 @@ inline void Foo::__crubit_field_offset_assertions() {
 }
 }  // namespace modules::impl_in_separate_private_module
 
-namespace modules::outer {
-
-namespace [[deprecated]] inner_deprecated {}
-
-}  // namespace modules::outer
-
-namespace modules::outer::middle {
-
-namespace [[deprecated]] innermost_deprecated {}
-
-}  // namespace modules::outer::middle
-
 #pragma clang diagnostic pop
 #endif  // THIRD_PARTY_CRUBIT_CC_BINDINGS_FROM_RS_TEST_MODULES_MODULES_GOLDEN

cc_bindings_from_rs/test/structs/structs_cc_api.h

@@ -959,8 +959,6 @@ inline std::int32_t get_x(::structs::default_repr::Point p) {
 
 }  // namespace structs::default_repr
 
-namespace structs::dynamically_sized_type {}
-
 namespace structs::interior_mutability {
 
 static_assert(