Improve virtual TS host and resolution

src/__tests__/tsHarness/resolutionUtils.ts

@@ -2,7 +2,6 @@ import {
   CompilerHost,
   StringLiteralLike,
   StringLiteral,
-  ScriptTarget,
   Identifier,
   SourceFile,
   Statement,
@@ -15,6 +14,8 @@ import {
   Mutable,
   Node,
   ResolutionMode,
+  JSDocParsingMode,
+  CreateSourceFileOptions,
   walkUpParenthesizedExpressions,
   isImportEqualsDeclaration,
   toPath,
@@ -41,17 +42,33 @@ import {
   isAmbientModule,
   getTextOfIdentifierOrLiteral,
   hasSyntacticModifier,
+  getEmitScriptTarget,
+  getSetExternalModuleIndicator,
 } from '@0no-co/typescript.js';
 
+import { compilerOptions } from './virtualHost';
+
 export function getModuleNames({ imports, moduleAugmentations }: SourceFile): StringLiteralLike[] {
   const res = [...imports];
   for (const aug of moduleAugmentations)
     if (aug.kind === (11 satisfies SyntaxKind.StringLiteral)) res.push(aug);
   return res;
 }
 
+function getCreateSourceFileOptions(): CreateSourceFileOptions {
+  const languageVersion = getEmitScriptTarget(compilerOptions);
+  const setExternalModuleIndicator = getSetExternalModuleIndicator(compilerOptions);
+  const jsDocParsingMode = 0 satisfies JSDocParsingMode.ParseAll;
+  return {
+    impliedNodeFormat: 99 satisfies ModuleKind.ESNext,
+    languageVersion,
+    setExternalModuleIndicator,
+    jsDocParsingMode,
+  };
+}
+
 export function findSourceFile(fileName: string, host: CompilerHost): SourceFile | undefined {
-  const file = host.getSourceFile(fileName, 99 satisfies ScriptTarget.ESNext);
+  const file = host.getSourceFile(fileName, getCreateSourceFileOptions());
   if (file) {
     const path = toPath(fileName, host.getCurrentDirectory(), host.getCanonicalFileName);
     file.fileName = file.originalFileName = fileName;

src/__tests__/tsHarness/typeCheckerHost.ts

@@ -96,16 +96,16 @@ export function createTypeHost(rootFileNames: readonly string[], host: CompilerH
     }
   }
 
-  for (const rootFileName of rootFileNames) {
-    const rootFile = getSourceFile(rootFileName);
-    if (rootFile) rootFiles.push(rootFile);
-  }
-
   if (!compilerOptions.noLib) {
     const libFile = getSourceFile(host.getDefaultLibFileName(compilerOptions));
     if (libFile) rootFiles.push(libFile);
   }
 
+  for (const rootFileName of rootFileNames) {
+    const rootFile = getSourceFile(rootFileName);
+    if (rootFile) rootFiles.push(rootFile);
+  }
+
   const files = [...importedFiles, ...rootFiles];
 
   const typeHost: TypeHost = {

src/__tests__/tsHarness/virtualHost.ts

@@ -4,6 +4,7 @@ import {
   ResolvedModule,
   CompilerHost,
   ScriptTarget,
+  CreateSourceFileOptions,
   SourceFile,
   JsxEmit,
   createModuleResolutionCache,
@@ -32,6 +33,8 @@ export const compilerOptions: CompilerOptions = {
   strict: false,
   noEmit: true,
   noLib: false,
+  disableReferencedProjectLoad: true,
+  disableSourceOfProjectReferenceRedirect: true,
   disableSizeLimit: true,
   disableSolutionSearching: true,
 };
@@ -56,10 +59,14 @@ class File {
     }
   }
 
-  toSourceFile(target: ScriptTarget) {
+  toSourceFile(languageVersionOrOptions: ScriptTarget | CreateSourceFileOptions) {
+    const target =
+      typeof languageVersionOrOptions === 'object'
+        ? languageVersionOrOptions.languageVersion
+        : languageVersionOrOptions;
     return (
       this.cache[target] ||
-      (this.cache[target] = createSourceFile(this.name, this.toString(), target))
+      (this.cache[target] = createSourceFile(this.name, this.toString(), languageVersionOrOptions))
     );
   }
 
@@ -132,14 +139,18 @@ export function createVirtualHost(files: Files) {
   }
 
   function split(filename: string): string[] {
-    return filename.split(path.sep).slice(1);
+    return filename !== path.sep ? filename.split(path.sep).slice(1) : [];
   }
 
   function lookup(filename: string): File | Directory | undefined {
     const parts = split(normalize(filename));
     let directory = root;
-    for (let i = 0; i < parts.length - 1; i++) directory = directory.dir(parts[i]);
-    return directory.get(parts[parts.length - 1]);
+    if (parts.length) {
+      for (let i = 0; i < parts.length - 1; i++) directory = directory.dir(parts[i]);
+      return directory.get(parts[parts.length - 1]);
+    } else {
+      return directory;
+    }
   }
 
   for (const key in files) {
@@ -155,20 +166,29 @@ export function createVirtualHost(files: Files) {
     getCanonicalFileName: normalize,
     getDefaultLibFileName() {
       // TODO: When another lib with references is selected, the resolution mode doesn't adapt
-      return '/node_modules/@0no-co/typescript.js/lib/lib.es5.d.ts';
+      return normalize('/node_modules/@0no-co/typescript.js/lib/lib.es5.d.ts');
     },
     getCurrentDirectory() {
       return path.sep;
     },
     getNewLine() {
       return '\n';
     },
+    getModuleResolutionCache() {
+      return cache;
+    },
     useCaseSensitiveFileNames() {
       return true;
     },
+    useSourceOfProjectReferenceRedirect() {
+      return false;
+    },
     fileExists(filename: string) {
       return lookup(filename) instanceof File;
     },
+    directoryExists(directoryName: string) {
+      return lookup(directoryName) instanceof Directory;
+    },
 
     writeFile(filename: string, content: Uint8Array | string) {
       const name = normalize(filename);
@@ -196,10 +216,13 @@ export function createVirtualHost(files: Files) {
       }
     },
 
-    getSourceFile(filename: string, target: ScriptTarget) {
+    getSourceFile(
+      filename: string,
+      languageVersionOrOptions: ScriptTarget | CreateSourceFileOptions
+    ) {
       const entry = lookup(filename);
       if (entry instanceof File) {
-        return entry.toSourceFile(target);
+        return entry.toSourceFile(languageVersionOrOptions);
       }
     },
 
@@ -211,10 +234,5 @@ export function createVirtualHost(files: Files) {
       }
       return resolvedModules;
     },
-
-    resolveRootModule(moduleName: string) {
-      return resolveModuleName(moduleName, '/', compilerOptions, this)?.resolvedModule
-        ?.resolvedFileName;
-    },
-  };
+  } satisfies CompilerHost;
 }