fix(fs): preserve promises namespace identity

changelog.d/9887-fs-promises-namespace-identity.md

@@ -0,0 +1,3 @@
+### Fixed
+
+- Reuse the canonical `fs/promises` and `stream/promises` namespace objects when their native-module references become values.

crates/perry-codegen/src/expr/property_get/tests.rs

@@ -315,6 +315,27 @@ fn fs_parent_promises_property_installs_before_resolution() {
     );
 }
 
+#[test]
+fn fs_promises_native_module_value_uses_submodule_singleton() {
+    let mut module = Module::new("fs_promises_native_module_value.ts");
+    module.init = vec![Stmt::Return(Some(Expr::NativeModuleRef(
+        "fs/promises".to_string(),
+    )))];
+
+    let ir = String::from_utf8(compile_module(&module, ir_opts(false, None)).unwrap())
+        .expect("LLVM IR should be UTF-8");
+    let install = ir
+        .find("call void @js_node_submod_install_fs_promises()")
+        .unwrap_or_else(|| panic!("fs/promises must emit its submodule installer:\n{ir}"));
+    let namespace = ir
+        .find("call double @js_node_submodule_namespace")
+        .unwrap_or_else(|| panic!("fs/promises must use its submodule singleton:\n{ir}"));
+    assert!(
+        install < namespace,
+        "fs/promises installation must precede namespace creation:\n{ir}"
+    );
+}
+
 /// #7753, paired with `pic_cache_words_match_codegen` in
 /// `perry-runtime/src/object/field_get_set/ic_miss.rs`.
 ///

crates/perry-codegen/src/expr/static_field_meta.rs

@@ -910,6 +910,22 @@ pub(crate) fn lower(ctx: &mut FnCtx<'_>, expr: &Expr) -> Result<String> {
         // require("node:fs"); fs.constants` (call-result shape, fallback
         // path here) both produce a real namespace object.
         Expr::NativeModuleRef(name) => {
+            if let Some(submod_key) = crate::nm_install::native_namespace_submodule_key(name) {
+                let submod_idx = ctx.strings.intern(submod_key);
+                let submod_bytes_global =
+                    format!("@{}", ctx.strings.entry(submod_idx).bytes_global);
+                let submod_len = submod_key.len().to_string();
+                let install_sym = crate::nm_install::nm_submod_install_symbol(submod_key);
+                let blk = ctx.block();
+                if let Some(symbol) = install_sym {
+                    blk.call_void(symbol, &[]);
+                }
+                return Ok(blk.call(
+                    DOUBLE,
+                    "js_node_submodule_namespace",
+                    &[(PTR, &submod_bytes_global), (I32, &submod_len)],
+                ));
+            }
             let mod_idx = ctx.strings.intern(name);
             let mod_bytes_global = format!("@{}", ctx.strings.entry(mod_idx).bytes_global);
             let mod_len_str = name.len().to_string();

crates/perry-codegen/src/lower_call/native/mod.rs

@@ -480,12 +480,7 @@ pub(crate) fn lower_native_method_call(
         // TAG_UNDEFINED sentinel below and `promises.realpath(p)` resolved
         // `undefined` (the compiled CLI's file cache then normalized every path to
         // `undefined` and each later fs call threw).
-        let normalized_module = module.strip_prefix("node:").unwrap_or(module);
-        let promises_submod_key = match normalized_module {
-            "fs/promises" => Some("fs_promises"),
-            "stream/promises" => Some("stream_promises"),
-            _ => None,
-        };
+        let promises_submod_key = crate::nm_install::native_namespace_submodule_key(module);
         if let Some(submod_key) = promises_submod_key {
             let submod_label = crate::expr::emit_string_literal_global(ctx, submod_key);
             let install_sym = crate::nm_install::nm_submod_install_symbol(submod_key);

crates/perry-codegen/src/nm_install.rs

@@ -151,6 +151,16 @@ pub(crate) fn nm_submod_install_symbol(key: &str) -> Option<&'static str> {
     }
 }
 
+/// Native-module spellings whose value is implemented by the node-submodule
+/// registry rather than a generic native-module namespace object.
+pub(crate) fn native_namespace_submodule_key(name: &str) -> Option<&'static str> {
+    match name.strip_prefix("node:").unwrap_or(name) {
+        "fs/promises" => Some("fs_promises"),
+        "stream/promises" => Some("stream_promises"),
+        _ => None,
+    }
+}
+
 #[allow(dead_code)] // consumed only by codegen configurations that emit dispatch declarations
 pub(crate) const NM_SUBMOD_INSTALL_SYMBOLS: &[&str] = &[
     "js_node_submod_install_vm",