Rewrite legacy API using containingUrl

.eslintrc

@@ -5,5 +5,19 @@
     // It would be nice to sort import declaration order as well, but that's not
     // autofixable and it's not worth the effort of handling manually.
     "sort-imports": ["error", {"ignoreDeclarationSort": true}],
+    // Match TypeScript style of exempting names starting with `_`.
+    // See: https://typescript-eslint.io/rules/no-unused-vars/
+    "@typescript-eslint/no-unused-vars": [
+      "error",
+      {
+        "args": "all",
+        "argsIgnorePattern": "^_",
+        "caughtErrors": "all",
+        "caughtErrorsIgnorePattern": "^_",
+        "destructuredArrayIgnorePattern": "^_",
+        "varsIgnorePattern": "^_",
+        "ignoreRestSiblings": true
+      }
+    ]
   }
 }

lib/src/compiler-path.ts

@@ -53,7 +53,7 @@ export const compilerCommand = (() => {
         `sass-embedded-${platform}-${arch}/dart-sass/src/sass.snapshot`
       ),
     ];
-  } catch (ignored) {
+  } catch (_ignored) {
     // ignored
   }
 

lib/src/compiler/utils.ts

@@ -10,7 +10,6 @@ import {Dispatcher, DispatcherHandlers} from '../dispatcher';
 import {Exception} from '../exception';
 import {ImporterRegistry} from '../importer-registry';
 import {
-  legacyImporterProtocol,
   removeLegacyImporter,
   removeLegacyImporterFromSpan,
 } from '../legacy/utils';
@@ -121,19 +120,12 @@ export function newCompileStringRequest(
   });
 
   const url = options?.url?.toString();
-  if (url && url !== legacyImporterProtocol) {
+  if (url) {
     input.url = url;
   }
 
   if (options && 'importer' in options && options.importer) {
     input.importer = importers.register(options.importer);
-  } else if (url === legacyImporterProtocol) {
-    input.importer = new proto.InboundMessage_CompileRequest_Importer({
-      importer: {case: 'path', value: p.resolve('.')},
-    });
-  } else {
-    // When importer is not set on the host, the compiler will set a
-    // FileSystemImporter if `url` is set to a file: url or a NoOpImporter.
   }
 
   const request = newCompileRequest(importers, options);

lib/src/importer-registry.ts

@@ -12,6 +12,8 @@ import * as utils from './utils';
 import {FileImporter, Importer, Options} from './vendor/sass';
 import * as proto from './vendor/embedded_sass_pb';
 import {PromiseOr, catchOr, thenOr} from './utils';
+import {LegacyImporterWrapper} from './legacy/importer';
+import {legacyImporterScheme} from './legacy/utils';
 
 const entryPointDirectoryKey = Symbol();
 
@@ -94,10 +96,15 @@ export class ImporterRegistry<sync extends 'sync' | 'async'> {
       }
 
       message.importer = {case: 'importerId', value: this.id};
-      message.nonCanonicalScheme =
-        typeof importer.nonCanonicalScheme === 'string'
-          ? [importer.nonCanonicalScheme]
-          : importer.nonCanonicalScheme ?? [];
+      if (importer instanceof LegacyImporterWrapper) {
+        message.nonCanonicalScheme = [legacyImporterScheme];
+        message.invertNonCanonicalScheme = true;
+      } else {
+        message.nonCanonicalScheme =
+          typeof importer.nonCanonicalScheme === 'string'
+            ? [importer.nonCanonicalScheme]
+            : importer.nonCanonicalScheme ?? [];
+      }
       this.importersById.set(this.id, importer);
     } else {
       message.importer = {case: 'fileImporterId', value: this.id};