node:net createServer: dotted form fails codegen, named-import form returns undefined at runtime

[proggeramlug]

Summary

Two separate defects in node:net's createServer on Perry 0.5.1010 — distinct from #1121 (which is node:http).

Repro A — dotted form fails codegen

// /tmp/test_net_server.ts
import * as net from "node:net";
const server = net.createServer((sock: any) => { sock.end("ok\n"); });
console.log("server =", server);
server.listen(18997, () => { console.log("LISTENING"); });

$ PERRY_ALLOW_PERRY_FEATURES=1 perry /tmp/test_net_server.ts -o /tmp/test_net_server
Error compiling module 'test_net_server.ts' (...) with --backend llvm:
  lowering entry of module 'test_net_server.ts':
    lowering init statements of module 'test_net_server.ts':
      perry-codegen Phase 2: expression NetCreateServer not yet supported

Repro B — named-import form compiles+links but returns undefined

// /tmp/test_net_server2.ts
import { createServer } from "node:net";
const server = createServer((sock: any) => { sock.end("ok\n"); });
console.log("server =", server);
if (server) server.listen(18996, () => { console.log("LISTENING"); });

$ PERRY_ALLOW_PERRY_FEATURES=1 perry /tmp/test_net_server2.ts -o /tmp/test_net_server2
Wrote executable: /tmp/test_net_server2

$ /tmp/test_net_server2
server = undefined

server is falsy, so server.listen(...) never gets called — silent failure. No listener bound, no error message.

Why

A — dotted form

HIR lowering creates Expr::NetCreateServer for net.createServer(...) (see crates/perry-hir/src/lower/expr_call.rs:1899 and :3393), and the variant is defined at crates/perry-hir/src/ir.rs:2024. But the LLVM codegen in crates/perry-codegen/src/expr.rs has no match arm for it — only perry-codegen-js (emit.rs:1782) and perry-codegen-wasm (emit.rs:9404) handle it. So it falls through to the generic "expression X not yet supported" at crates/perry-codegen/src/expr.rs:13659.

The runtime symbol js_net_create_server exists (crates/perry-runtime/src/net.rs:35) and is declared in crates/perry-codegen/src/runtime_decls.rs:2690 — only the lowering arm in LLVM codegen is missing.

B — named-import form

import { createServer } from "node:net"; createServer(handler) reaches a different lowering path that doesn't go through Expr::NetCreateServer. It compiles into something that produces undefined at runtime instead of a Server handle. Worth investigating whether this should also synthesize a NetCreateServer HIR node, or whether the bare-call path needs its own native-module dispatch.

Fix sketch

1. A: Add an Expr::NetCreateServer match arm in crates/perry-codegen/src/expr.rs that lowers to a call of js_net_create_server(options_i64, listener_i64) — mirror the shape of the existing NetCreateConnection / similar handlers (runtime_decls.rs:2690 already declares the signature: I64, &[I64, I64]).
2. B: In crates/perry-hir/src/lower/expr_call.rs, find the named-import-of-createServer path (parallel to the existing ("net", "createConnection") named-import handling at lines 1896-1899) and synthesize the same Expr::NetCreateServer node so both forms converge on (1).

Environment

• perry 0.5.1010 (HEAD: 89786c6)
• macOS arm64

Refs

• http: createServer/Server.listen/ServerResponse.end missing from stdlib runtime (api manifest claims support) #1121 — node:http createServer (sibling issue; my testing shows that one actually works on 0.5.1010 under PERRY_ALLOW_PERRY_FEATURES=1 with import { createServer } from "node:http" — separate followup will comment on http: createServer/Server.listen/ServerResponse.end missing from stdlib runtime (api manifest claims support) #1121)
• fastify reply: returning a Buffer is JSON-serialized; HEAD requests 404 on registered GET routes #1120 — fastify Buffer JSON-serialization (different module surface)