feat(unstable): ability to `npm install` then `deno run main.ts` (#20967)

This PR adds a new unstable "bring your own node_modules" (BYONM)
functionality currently behind a `--unstable-byonm` flag (`"unstable":
["byonm"]` in a deno.json).

This enables users to run a separate install command (ex. `npm install`,
`pnpm install`) then run `deno run main.ts` and Deno will respect the
layout of the node_modules directory as setup by the separate install
command. It also works with npm/yarn/pnpm workspaces.

For this PR, the behaviour is opted into by specifying
`--unstable-byonm`/`"unstable": ["byonm"]`, but in the future we may
make this the default behaviour as outlined in
https://github.com/denoland/deno/issues/18967#issuecomment-1761248941

This is an extremely rough initial implementation. Errors are
terrible in this and the LSP requires frequent restarts. Improvements
will be done in follow up PRs.

1 files changed, 14 insertions, 15 deletions

diff --git a/cli/cache/mod.rs b/cli/cache/mod.rs
index 1d6a79963..5cc91f50f 100644
--- a/cli/cache/mod.rs
+++ b/cli/cache/mod.rs
@@ -4,6 +4,7 @@ use crate::args::CacheSetting;
 use crate::errors::get_error_class_name;
 use crate::file_fetcher::FetchOptions;
 use crate::file_fetcher::FileFetcher;
+use crate::npm::CliNpmResolver;
 use crate::util::fs::atomic_write_file;
 
 use deno_ast::MediaType;
@@ -101,10 +102,10 @@ pub struct FetchCacher {
   file_fetcher: Arc<FileFetcher>,
   file_header_overrides: HashMap<ModuleSpecifier, HashMap<String, String>>,
   global_http_cache: Arc<GlobalHttpCache>,
+  npm_resolver: Arc<dyn CliNpmResolver>,
   parsed_source_cache: Arc<ParsedSourceCache>,
   permissions: PermissionsContainer,
   cache_info_enabled: bool,
-  maybe_local_node_modules_url: Option<ModuleSpecifier>,
 }
 
 impl FetchCacher {
@@ -113,19 +114,19 @@ impl FetchCacher {
     file_fetcher: Arc<FileFetcher>,
     file_header_overrides: HashMap<ModuleSpecifier, HashMap<String, String>>,
     global_http_cache: Arc<GlobalHttpCache>,
+    npm_resolver: Arc<dyn CliNpmResolver>,
     parsed_source_cache: Arc<ParsedSourceCache>,
     permissions: PermissionsContainer,
-    maybe_local_node_modules_url: Option<ModuleSpecifier>,
   ) -> Self {
     Self {
       emit_cache,
       file_fetcher,
       file_header_overrides,
       global_http_cache,
+      npm_resolver,
       parsed_source_cache,
       permissions,
       cache_info_enabled: false,
-      maybe_local_node_modules_url,
     }
   }
 
@@ -214,20 +215,18 @@ impl Loader for FetchCacher {
   ) -> LoadFuture {
     use deno_graph::source::CacheSetting as LoaderCacheSetting;
 
-    if let Some(node_modules_url) = self.maybe_local_node_modules_url.as_ref() {
+    if specifier.path().contains("/node_modules/") {
       // The specifier might be in a completely different symlinked tree than
-      // what the resolved node_modules_url is in (ex. `/my-project-1/node_modules`
-      // symlinked to `/my-project-2/node_modules`), so first check if the path
-      // is in a node_modules dir to avoid needlessly canonicalizing, then compare
+      // what the node_modules url is in (ex. `/my-project-1/node_modules`
+      // symlinked to `/my-project-2/node_modules`), so first we checked if the path
+      // is in a node_modules dir to avoid needlessly canonicalizing, then now compare
       // against the canonicalized specifier.
-      if specifier.path().contains("/node_modules/") {
-        let specifier =
-          crate::node::resolve_specifier_into_node_modules(specifier);
-        if specifier.as_str().starts_with(node_modules_url.as_str()) {
-          return Box::pin(futures::future::ready(Ok(Some(
-            LoadResponse::External { specifier },
-          ))));
-        }
+      let specifier =
+        crate::node::resolve_specifier_into_node_modules(specifier);
+      if self.npm_resolver.in_npm_package(&specifier) {
+        return Box::pin(futures::future::ready(Ok(Some(
+          LoadResponse::External { specifier },
+        ))));
       }
     }