feat(compat): inject Node globals (#12342)

This commit adds automatic injection of Node globals when "--compat" flag
is present.

This is done by executing "https://deno.land/std/node/global.ts" as a "side module",
before main module is executed.

This commit makes "--compat" required to be used with "--unstable" flag, as some
of Node globals require unstable Deno APIs.

8 files changed, 75 insertions, 15 deletions

diff --git a/cli/compat.rs b/cli/compat.rs
index eb67f4d12..4b64a501d 100644
--- a/cli/compat.rs
+++ b/cli/compat.rs
@@ -1,7 +1,10 @@
 // Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
 
+use deno_core::url::Url;
 use std::collections::HashMap;
 
+static STD_NODE: &str = "https://deno.land/std/node/";
+
 static SUPPORTED_MODULES: &[&str] = &[
   "assert",
   "assert/strict",
@@ -47,12 +50,20 @@ static SUPPORTED_MODULES: &[&str] = &[
   "zlib",
 ];
 
+pub fn get_node_globals_url() -> Url {
+  Url::parse(&format!("{}global.ts", STD_NODE)).unwrap()
+}
+
+/// Create a map that can be used to update import map.
+///
+/// Keys are built-in Node modules (and built-ins prefixed with "node:"), while
+/// values are URLs pointing to relevant files in deno.land/std/node/ directory.
 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);
+    let module_url = format!("{}{}.ts", STD_NODE, module);
     mappings.insert(module.to_string(), module_url.clone());
 
     // Support for `node:<module_name>`
diff --git a/cli/flags.rs b/cli/flags.rs
index 3075eda40..df17c08da 100644
--- a/cli/flags.rs
+++ b/cli/flags.rs
@@ -1627,7 +1627,8 @@ 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'.")
+    .requires("unstable")
+    .help("Node compatibility mode. Currently only enables built-in node modules like 'fs' and globals like 'process'.")
 }
 
 fn watch_arg<'a, 'b>() -> Arg<'a, 'b> {
@@ -4453,7 +4454,8 @@ mod tests {
 
   #[test]
   fn compat() {
-    let r = flags_from_vec(svec!["deno", "run", "--compat", "foo.js"]);
+    let r =
+      flags_from_vec(svec!["deno", "run", "--compat", "--unstable", "foo.js"]);
     assert_eq!(
       r.unwrap(),
       Flags {
@@ -4461,6 +4463,7 @@ mod tests {
           script: "foo.js".to_string(),
         }),
         compat: true,
+        unstable: true,
         ..Flags::default()
       }
     );
diff --git a/cli/main.rs b/cli/main.rs
index d7601249d..b444f101e 100644
--- a/cli/main.rs
+++ b/cli/main.rs
@@ -568,7 +568,7 @@ async fn eval_command(
   // Force TypeScript compile.
   let main_module = resolve_url_or_path("./$deno$eval.ts").unwrap();
   let permissions = Permissions::from_options(&flags.clone().into());
-  let ps = ProcState::build(flags).await?;
+  let ps = ProcState::build(flags.clone()).await?;
   let mut worker =
     create_main_worker(&ps, main_module.clone(), permissions, None);
   // Create a dummy source file.
@@ -600,6 +600,11 @@ async fn eval_command(
   // to allow module access by TS compiler.
   ps.file_fetcher.insert_cached(file);
   debug!("main_module {}", &main_module);
+  if flags.compat {
+    worker
+      .execute_side_module(&compat::get_node_globals_url())
+      .await?;
+  }
   worker.execute_main_module(&main_module).await?;
   worker.execute_script(
     &located_script_name!(),
@@ -845,6 +850,11 @@ async fn run_from_stdin(flags: Flags) -> Result<(), AnyError> {
   ps.file_fetcher.insert_cached(source_file);
 
   debug!("main_module {}", main_module);
+  if flags.compat {
+    worker
+      .execute_side_module(&compat::get_node_globals_url())
+      .await?;
+  }
   worker.execute_main_module(&main_module).await?;
   worker.execute_script(
     &located_script_name!(),
@@ -912,13 +922,15 @@ async fn run_with_watch(flags: Flags, script: String) -> Result<(), AnyError> {
   struct FileWatcherModuleExecutor {
     worker: MainWorker,
     pending_unload: bool,
+    compat: bool,
   }
 
   impl FileWatcherModuleExecutor {
-    pub fn new(worker: MainWorker) -> FileWatcherModuleExecutor {
+    pub fn new(worker: MainWorker, compat: bool) -> FileWatcherModuleExecutor {
       FileWatcherModuleExecutor {
         worker,
         pending_unload: false,
+        compat,
       }
     }
 
@@ -928,6 +940,12 @@ async fn run_with_watch(flags: Flags, script: String) -> Result<(), AnyError> {
       &mut self,
       main_module: &ModuleSpecifier,
     ) -> Result<(), AnyError> {
+      if self.compat {
+        self
+          .worker
+          .execute_side_module(&compat::get_node_globals_url())
+          .await?;
+      }
       self.worker.execute_main_module(main_module).await?;
       self.worker.execute_script(
         &located_script_name!(),
@@ -967,16 +985,14 @@ async fn run_with_watch(flags: Flags, script: String) -> Result<(), AnyError> {
 
   let operation = |(ps, main_module): (ProcState, ModuleSpecifier)| {
     let flags = flags.clone();
-    let permissions = Permissions::from_options(&flags.into());
+    let permissions = Permissions::from_options(&flags.clone().into());
     async move {
       // We make use an module executor guard to ensure that unload is always fired when an
       // operation is called.
-      let mut executor = FileWatcherModuleExecutor::new(create_main_worker(
-        &ps,
-        main_module.clone(),
-        permissions,
-        None,
-      ));
+      let mut executor = FileWatcherModuleExecutor::new(
+        create_main_worker(&ps, main_module.clone(), permissions, None),
+        flags.compat,
+      );
 
       executor.execute(&main_module).await?;
 
@@ -1022,6 +1038,11 @@ async fn run_command(
     };
 
   debug!("main_module {}", main_module);
+  if flags.compat {
+    worker
+      .execute_side_module(&compat::get_node_globals_url())
+      .await?;
+  }
   worker.execute_main_module(&main_module).await?;
   worker.execute_script(
     &located_script_name!(),
diff --git a/cli/proc_state.rs b/cli/proc_state.rs
index 48dc335f0..2e1fb0e31 100644
--- a/cli/proc_state.rs
+++ b/cli/proc_state.rs
@@ -1,6 +1,7 @@
 // Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
 
 use crate::colors;
+use crate::compat;
 use crate::config_file::ConfigFile;
 use crate::deno_dir;
 use crate::file_fetcher::CacheSetting;
@@ -217,7 +218,7 @@ impl ProcState {
             .unwrap()
         }
       };
-      let node_builtins = crate::compat::get_mapped_node_builtins();
+      let node_builtins = compat::get_mapped_node_builtins();
       let diagnostics = import_map.update_imports(node_builtins)?;
 
       if !diagnostics.is_empty() {
@@ -353,6 +354,9 @@ impl ProcState {
     )?));
     let mut builder =
       GraphBuilder::new(handler, maybe_import_map, self.lockfile.clone());
+    if self.flags.compat {
+      builder.add(&compat::get_node_globals_url(), false).await?;
+    }
     builder.add(&specifier, is_dynamic).await?;
     builder.analyze_config_file(&self.maybe_config_file).await?;
     let mut graph = builder.get_graph();
diff --git a/cli/tests/integration/compat_tests.rs b/cli/tests/integration/compat_tests.rs
index e1da32caf..6743dada1 100644
--- a/cli/tests/integration/compat_tests.rs
+++ b/cli/tests/integration/compat_tests.rs
@@ -2,6 +2,11 @@
 
 use crate::itest;
 
+itest!(globals {
+  args: "run --compat --unstable --allow-read --allow-env compat/globals.ts",
+  output: "compat/globals.out",
+});
+
 itest!(fs_promises {
   args: "run --compat --unstable -A compat/fs_promises.js",
   output: "compat/fs_promises.out",
@@ -13,7 +18,7 @@ itest!(node_prefix_fs_promises {
 });
 
 itest!(existing_import_map {
-  args: "run --compat --import-map compat/existing_import_map.json compat/fs_promises.js",
+  args: "run --compat --unstable --import-map compat/existing_import_map.json compat/fs_promises.js",
   output: "compat/existing_import_map.out",
   exit_code: 1,
 });
diff --git a/cli/tests/testdata/compat/existing_import_map.out b/cli/tests/testdata/compat/existing_import_map.out
index 0e319b115..cbff0cc51 100644
--- a/cli/tests/testdata/compat/existing_import_map.out
+++ b/cli/tests/testdata/compat/existing_import_map.out
@@ -2,4 +2,5 @@
 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]
\ No newline at end of file
+[WILDCARD]
+error: Cannot resolve module [WILDCARD]
diff --git a/cli/tests/testdata/compat/globals.out b/cli/tests/testdata/compat/globals.out
new file mode 100644
index 000000000..0bc09137b
--- /dev/null
+++ b/cli/tests/testdata/compat/globals.out
@@ -0,0 +1,7 @@
+[WILDCARD]
+process {
+[WILDCARD]
+}
+[Function: Buffer]
+[Function: setImmediate]
+[Function: clearTimeout]
diff --git a/cli/tests/testdata/compat/globals.ts b/cli/tests/testdata/compat/globals.ts
new file mode 100644
index 000000000..39a555cbf
--- /dev/null
+++ b/cli/tests/testdata/compat/globals.ts
@@ -0,0 +1,8 @@
+if (global != window) {
+  throw new Error("global is not equal to window");
+}
+
+console.log(process);
+console.log(Buffer);
+console.log(setImmediate);
+console.log(clearImmediate);