2 files changed, 56 insertions, 28 deletions

diff --git a/cli/args/flags.rs b/cli/args/flags.rs
index 138d77359..588f75dbb 100644
--- a/cli/args/flags.rs
+++ b/cli/args/flags.rs
@@ -407,6 +407,7 @@ pub struct Flags {
   pub seed: Option<u64>,
   pub unstable: bool,
   pub unstable_bare_node_builtlins: bool,
+  pub unstable_byonm: bool,
   pub unsafely_ignore_certificate_errors: Option<Vec<String>>,
   pub v8_flags: Vec<String>,
 }
@@ -803,9 +804,9 @@ pub fn flags_from_vec(args: Vec<String>) -> clap::error::Result<Flags> {
     flags.unstable = true;
   }
 
-  if matches.get_flag("unstable-bare-node-builtins") {
-    flags.unstable_bare_node_builtlins = true;
-  }
+  flags.unstable_bare_node_builtlins =
+    matches.get_flag("unstable-bare-node-builtins");
+  flags.unstable_byonm = matches.get_flag("unstable-byonm");
 
   if matches.get_flag("quiet") {
     flags.log_level = Some(Level::Error);
@@ -912,6 +913,15 @@ fn clap_root() -> Command {
         .global(true),
     )
     .arg(
+      Arg::new("unstable-byonm")
+        .long("unstable-byonm")
+        .help("Enable unstable 'bring your own node_modules' feature")
+        .env("DENO_UNSTABLE_BYONM")
+        .value_parser(FalseyValueParser::new())
+        .action(ArgAction::SetTrue)
+        .global(true),
+    )
+    .arg(
       Arg::new("log-level")
         .short('L')
         .long("log-level")
diff --git a/cli/args/mod.rs b/cli/args/mod.rs
index 390e16698..ab8d6b503 100644
--- a/cli/args/mod.rs
+++ b/cli/args/mod.rs
@@ -76,25 +76,29 @@ use deno_config::FmtConfig;
 use deno_config::LintConfig;
 use deno_config::TestConfig;
 
-static NPM_REGISTRY_DEFAULT_URL: Lazy<Url> = Lazy::new(|| {
-  let env_var_name = "NPM_CONFIG_REGISTRY";
-  if let Ok(registry_url) = std::env::var(env_var_name) {
-    // ensure there is a trailing slash for the directory
-    let registry_url = format!("{}/", registry_url.trim_end_matches('/'));
-    match Url::parse(&registry_url) {
-      Ok(url) => {
-        return url;
-      }
-      Err(err) => {
-        log::debug!("Invalid {} environment variable: {:#}", env_var_name, err,);
+pub fn npm_registry_default_url() -> &'static Url {
+  static NPM_REGISTRY_DEFAULT_URL: Lazy<Url> = Lazy::new(|| {
+    let env_var_name = "NPM_CONFIG_REGISTRY";
+    if let Ok(registry_url) = std::env::var(env_var_name) {
+      // ensure there is a trailing slash for the directory
+      let registry_url = format!("{}/", registry_url.trim_end_matches('/'));
+      match Url::parse(&registry_url) {
+        Ok(url) => {
+          return url;
+        }
+        Err(err) => {
+          log::debug!(
+            "Invalid {} environment variable: {:#}",
+            env_var_name,
+            err,
+          );
+        }
       }
     }
-  }
 
-  Url::parse("https://registry.npmjs.org").unwrap()
-});
+    Url::parse("https://registry.npmjs.org").unwrap()
+  });
 
-pub fn npm_registry_default_url() -> &'static Url {
   &NPM_REGISTRY_DEFAULT_URL
 }
 
@@ -570,10 +574,16 @@ pub fn get_root_cert_store(
 /// State provided to the process via an environment variable.
 #[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct NpmProcessState {
-  pub snapshot: deno_npm::resolution::SerializedNpmResolutionSnapshot,
+  pub kind: NpmProcessStateKind,
   pub local_node_modules_path: Option<String>,
 }
 
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub enum NpmProcessStateKind {
+  Snapshot(deno_npm::resolution::SerializedNpmResolutionSnapshot),
+  Byonm,
+}
+
 const RESOLUTION_STATE_ENV_VAR_NAME: &str =
   "DENO_DONT_USE_INTERNAL_NODE_COMPAT_STATE";
 
@@ -875,9 +885,11 @@ impl CliOptions {
   pub fn resolve_npm_resolution_snapshot(
     &self,
   ) -> Result<Option<ValidSerializedNpmResolutionSnapshot>, AnyError> {
-    if let Some(state) = &*NPM_PROCESS_STATE {
+    if let Some(NpmProcessStateKind::Snapshot(snapshot)) =
+      NPM_PROCESS_STATE.as_ref().map(|s| &s.kind)
+    {
       // TODO(bartlomieju): remove this clone
-      Ok(Some(state.snapshot.clone().into_valid()?))
+      Ok(Some(snapshot.clone().into_valid()?))
     } else {
       Ok(None)
     }
@@ -926,13 +938,6 @@ impl CliOptions {
     })
   }
 
-  pub fn node_modules_dir_specifier(&self) -> Option<ModuleSpecifier> {
-    self
-      .maybe_node_modules_folder
-      .as_ref()
-      .map(|path| ModuleSpecifier::from_directory_path(path).unwrap())
-  }
-
   pub fn vendor_dir_path(&self) -> Option<&PathBuf> {
     self.maybe_vendor_folder.as_ref()
   }
@@ -1226,6 +1231,19 @@ impl CliOptions {
         .unwrap_or(false)
   }
 
+  pub fn unstable_byonm(&self) -> bool {
+    self.flags.unstable_byonm
+      || NPM_PROCESS_STATE
+        .as_ref()
+        .map(|s| matches!(s.kind, NpmProcessStateKind::Byonm))
+        .unwrap_or(false)
+      || self
+        .maybe_config_file()
+        .as_ref()
+        .map(|c| c.json.unstable.iter().any(|c| c == "byonm"))
+        .unwrap_or(false)
+  }
+
   pub fn v8_flags(&self) -> &Vec<String> {
     &self.flags.v8_flags
   }