feat: add --compat flag to provide built-in Node modules (denoland#12293

)

This commit adds "--compat" flag. When the flag is passed a set of mappings for
built-in Node modules is injected into the import map. If user doesn't
explicitly provide an import map (using "--import-map" flag) then a map is
created on the fly. If there are already existing mappings in import map that
would clash with built-in Node modules a set of diagnostics is printed to the
terminal with suggestions how to proceed.

cli/Cargo.toml

@@ -59,7 +59,7 @@ encoding_rs = "0.8.28"
 env_logger = "0.8.4"
 fancy-regex = "0.7.1"
 http = "0.2.4"
-import_map = "0.3.0"
+import_map = "0.3.3"
 jsonc-parser = { version = "0.17.0", features = ["serde"] }
 lazy_static = "1.4.0"
 libc = "0.2.101"

cli/compat.rs

@@ -0,0 +1,60 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+
+use std::collections::HashMap;
+
+static SUPPORTED_MODULES: &[&str] = &[
+ "assert",
+ "assert/strict",
+ "async_hooks",
+ "buffer",
+ "child_process",
+ "cluster",
+ "console",
+ "constants",
+ "crypto",
+ "dgram",
+ "dns",
+ "domain",
+ "events",
+ "fs",
+ "fs/promises",
+ "http",
+ "https",
+ "module",
+ "net",
+ "os",
+ "path",
+ "path/posix",
+ "path/win32",
+ "perf_hooks",
+ "process",
+ "querystring",
+ "readline",
+ "stream",
+ "stream/promises",
+ "stream/web",
+ "string_decoder",
+ "sys",
+ "timers",
+ "timers/promises",
+ "tls",
+ "tty",
+ "url",
+ "util",
+ "util/types",
+ "v8",
+ "vm",
+ "zlib",
+];
+
+pub fn get_mapped_node_builtins() -> HashMap<String, String> {
+ let mut mappings = HashMap::new();
+
+ for module in SUPPORTED_MODULES {
+ // TODO(bartlomieju): this is unversioned, and should be fixed to use latest stable?
+ let module_url = format!("https://deno.land/std/node/{}.ts", module);
+ mappings.insert(module.to_string(), module_url);
+ }
+
+ mappings
+}

cli/flags.rs

@@ -222,6 +222,9 @@ pub struct Flags {
  pub log_level: Option<Level>,
  pub no_check: bool,
  pub no_remote: bool,
+ /// If true, a list of Node built-in modules will be injected into
+ /// the import map.
+ pub compat: bool,
  pub prompt: bool,
  pub reload: bool,
  pub repl: bool,
@@ -1490,6 +1493,7 @@ fn runtime_args<'a, 'b>(
  .arg(v8_flags_arg())
  .arg(seed_arg())
  .arg(enable_testing_features_arg())
+ .arg(compat_arg())
 }
 
 fn inspect_args<'a, 'b>(app: App<'a, 'b>) -> App<'a, 'b> {
@@ -1619,6 +1623,12 @@ fn seed_arg<'a, 'b>() -> Arg<'a, 'b> {
  })
 }
 
+fn compat_arg<'a, 'b>() -> Arg<'a, 'b> {
+ Arg::with_name("compat")
+ .long("compat")
+ .help("Node compatibility mode. Currently only enables built-in node modules like 'fs'.")
+}
+
 fn watch_arg<'a, 'b>() -> Arg<'a, 'b> {
  Arg::with_name("watch")
  .long("watch")
@@ -2228,6 +2238,7 @@ fn runtime_args_parse(
  location_arg_parse(flags, matches);
  v8_flags_arg_parse(flags, matches);
  seed_arg_parse(flags, matches);
+ compat_arg_parse(flags, matches);
  inspect_arg_parse(flags, matches);
  enable_testing_features_arg_parse(flags, matches);
 }
@@ -2313,6 +2324,12 @@ fn seed_arg_parse(flags: &mut Flags, matches: &ArgMatches) {
  }
 }
 
+fn compat_arg_parse(flags: &mut Flags, matches: &ArgMatches) {
+ if matches.is_present("compat") {
+ flags.compat = true;
+ }
+}
+
 fn no_check_arg_parse(flags: &mut Flags, matches: &clap::ArgMatches) {
  if matches.is_present("no-check") {
  flags.no_check = true;
@@ -4431,4 +4448,19 @@ mod tests {
  .to_string()
  .contains("Expected protocol \"http\" or \"https\""));
  }
+
+ #[test]
+ fn compat() {
+ let r = flags_from_vec(svec!["deno", "run", "--compat", "foo.js"]);
+ assert_eq!(
+ r.unwrap(),
+ Flags {
+ subcommand: DenoSubcommand::Run(RunFlags {
+ script: "foo.js".to_string(),
+ }),
+ compat: true,
+ ..Flags::default()
+ }
+ );
+ }
 }

cli/main.rs

@@ -3,6 +3,7 @@
 mod ast;
 mod auth_tokens;
 mod checksum;
+mod compat;
 mod config_file;
 mod deno_dir;
 mod diagnostics;

cli/proc_state.rs

@@ -36,6 +36,7 @@ use deno_tls::rustls_native_certs::load_native_certs;
 use deno_tls::webpki_roots::TLS_SERVER_ROOTS;
 use import_map::ImportMap;
 use log::debug;
+use log::info;
 use log::warn;
 use std::collections::HashMap;
 use std::collections::HashSet;
@@ -182,7 +183,7 @@ impl ProcState {
  None
  };
 
- let maybe_import_map: Option<ImportMap> =
+ let mut maybe_import_map: Option<ImportMap> =
  match flags.import_map_path.as_ref() {
  None => None,
  Some(import_map_url) => {
@@ -204,6 +205,32 @@ impl ProcState {
  }
  };
 
+ if flags.compat {
+ let mut import_map = match maybe_import_map {
+ Some(import_map) => import_map,
+ None => {
+ // INFO: we're creating an empty import map, with its specifier pointing
+ // to `CWD/node_import_map.json` to make sure the map still works as expected.
+ let import_map_specifier =
+ std::env::current_dir()?.join("node_import_map.json");
+ ImportMap::from_json(import_map_specifier.to_str().unwrap(), "{}")
+ .unwrap()
+ }
+ };
+ let node_builtins = crate::compat::get_mapped_node_builtins();
+ let diagnostics = import_map.update_imports(node_builtins)?;
+
+ if !diagnostics.is_empty() {
+ info!("Some Node built-ins were not added to the import map:");
+ for diagnostic in diagnostics {
+ info!(" - {}", diagnostic);
+ }
+ info!("If you want to use Node built-ins provided by Deno remove listed specifiers from \"imports\" mapping in the import map file.");
+ }
+
+ maybe_import_map = Some(import_map);
+ }
+
  let maybe_inspect_host = flags.inspect.or(flags.inspect_brk);
  let maybe_inspector_server = maybe_inspect_host.map(|host| {
  Arc::new(InspectorServer::new(host, version::get_user_agent()))

cli/tests/integration/compat_tests.rs

@@ -0,0 +1,14 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+
+use crate::itest;
+
+itest!(fs_promises {
+ args: "run --compat --unstable -A compat/fs_promises.js",
+ output: "compat/fs_promises.out",
+});
+
+itest!(existing_import_map {
+ args: "run --compat --import-map compat/existing_import_map.json compat/fs_promises.js",
+ output: "compat/existing_import_map.out",
+ exit_code: 1,
+});

cli/tests/integration/mod.rs

@@ -54,6 +54,8 @@ macro_rules! itest_flaky(
 mod bundle;
 #[path = "cache_tests.rs"]
 mod cache;
+#[path = "compat_tests.rs"]
+mod compat;
 #[path = "compile_tests.rs"]
 mod compile;
 #[path = "coverage_tests.rs"]

cli/tests/testdata/compat/existing_import_map.json

@@ -0,0 +1,5 @@
+{
+ "imports": {
+ "fs/promises": "./non_existent_file.js"
+ }
+}

cli/tests/testdata/compat/existing_import_map.out

@@ -0,0 +1,5 @@
+[WILDCARD]
+Some Node built-ins were not added to the import map:
+ - "fs/promises" already exists and is mapped to "[WILDCARD]non_existent_file.js"
+If you want to use Node built-ins provided by Deno remove listed specifiers from "imports" mapping in the import map file.
+error: Cannot resolve module [WILDCARD]

cli/tests/testdata/compat/fs_promises.js

@@ -0,0 +1,3 @@
+import fs from "fs/promises";
+const data = await fs.readFile("compat/test.txt", "utf-8");
+console.log(data);

cli/tests/testdata/compat/fs_promises.out

@@ -0,0 +1,2 @@
+[WILDCARD]
+This is some example text that will be read using compatiblity mode.

cli/tests/testdata/compat/test.txt

@@ -0,0 +1 @@
+This is some example text that will be read using compatiblity mode.

cli/tools/standalone.rs

@@ -227,6 +227,7 @@ pub fn compile_to_runtime_flags(
  lock: None,
  log_level: flags.log_level,
  no_check: false,
+ compat: flags.compat,
  unsafely_ignore_certificate_errors: flags
  .unsafely_ignore_certificate_errors,
  no_remote: false,