Add auto-import for the package.json imports field

src/compiler/moduleSpecifiers.ts

@@ -49,6 +49,7 @@ import {
     getRelativePathFromDirectory,
     getRelativePathToDirectoryOrUrl,
     getResolvePackageJsonExports,
+    getResolvePackageJsonImports,
     getSourceFileOfModule,
     getSupportedExtensions,
     getTextOfIdentifierOrLiteral,
@@ -89,6 +90,7 @@ import {
     pathIsBareSpecifier,
     pathIsRelative,
     PropertyAccessExpression,
+    readJson,
     removeExtension,
     removeFileExtension,
     removeSuffix,
@@ -456,7 +458,7 @@ function getLocalModuleSpecifier(moduleFileName: string, info: Info, compilerOpt
     const allowedEndings = getAllowedEndingsInPrefererredOrder(importMode);
     const relativePath = rootDirs && tryGetModuleNameFromRootDirs(rootDirs, moduleFileName, sourceDirectory, getCanonicalFileName, allowedEndings, compilerOptions) ||
         processEnding(ensurePathIsNonModuleName(getRelativePathFromDirectory(sourceDirectory, moduleFileName, getCanonicalFileName)), allowedEndings, compilerOptions);
-    if (!baseUrl && !paths || relativePreference === RelativePreference.Relative) {
+    if (!baseUrl && !paths && !getResolvePackageJsonImports(compilerOptions) || relativePreference === RelativePreference.Relative) {
         return pathsOnly ? undefined : relativePath;
     }
 
@@ -466,12 +468,14 @@ function getLocalModuleSpecifier(moduleFileName: string, info: Info, compilerOpt
         return pathsOnly ? undefined : relativePath;
     }
 
-    const fromPaths = paths && tryGetModuleNameFromPaths(relativeToBaseUrl, paths, allowedEndings, host, compilerOptions);
+    const fromPackageJsonImports = pathsOnly ? undefined : tryGetModuleNameFromPackageJsonImports(moduleFileName, sourceDirectory, compilerOptions, host, importMode);
+
+    const fromPaths = pathsOnly || fromPackageJsonImports === undefined ? paths && tryGetModuleNameFromPaths(relativeToBaseUrl, paths, allowedEndings, host, compilerOptions) : undefined;
     if (pathsOnly) {
         return fromPaths;
     }
 
-    const maybeNonRelative = fromPaths === undefined && baseUrl !== undefined ? processEnding(relativeToBaseUrl, allowedEndings, compilerOptions) : fromPaths;
+    const maybeNonRelative = fromPackageJsonImports ?? (fromPaths === undefined && baseUrl !== undefined ? processEnding(relativeToBaseUrl, allowedEndings, compilerOptions) : fromPaths);
     if (!maybeNonRelative) {
         return relativePath;
     }
@@ -538,8 +542,8 @@ function getNearestAncestorDirectoryWithPackageJson(host: ModuleSpecifierResolut
     if (host.getNearestAncestorDirectoryWithPackageJson) {
         return host.getNearestAncestorDirectoryWithPackageJson(fileName);
     }
-    return !!forEachAncestorDirectory(fileName, directory => {
-        return host.fileExists(combinePaths(directory, "package.json")) ? true : undefined;
+    return forEachAncestorDirectory(fileName, directory => {
+        return host.fileExists(combinePaths(directory, "package.json")) ? directory : undefined;
     });
 }
 
@@ -808,7 +812,7 @@ const enum MatchingMode {
     Pattern
 }
 
-function tryGetModuleNameFromExports(options: CompilerOptions, targetFilePath: string, packageDirectory: string, packageName: string, exports: unknown, conditions: string[], mode = MatchingMode.Exact): { moduleFileToTry: string } | undefined {
+function tryGetModuleNameFromExportsOrImports(options: CompilerOptions, targetFilePath: string, packageDirectory: string, packageName: string, exports: unknown, conditions: string[], mode: MatchingMode): { moduleFileToTry: string } | undefined {
     if (typeof exports === "string") {
         const pathOrPattern = getNormalizedAbsolutePath(combinePaths(packageDirectory, exports), /*currentDirectory*/ undefined);
         const extensionSwappedTarget = hasTSFileExtension(targetFilePath) ? removeFileExtension(targetFilePath) + tryGetJSExtensionForFile(targetFilePath, options) : undefined;
@@ -819,6 +823,10 @@ function tryGetModuleNameFromExports(options: CompilerOptions, targetFilePath: s
                 }
                 break;
             case MatchingMode.Directory:
+                if (extensionSwappedTarget && containsPath(pathOrPattern, extensionSwappedTarget)) {
+                    const fragment = getRelativePathFromDirectory(pathOrPattern, extensionSwappedTarget, /*ignoreCase*/ false);
+                    return { moduleFileToTry: getNormalizedAbsolutePath(combinePaths(combinePaths(packageName, exports), fragment), /*currentDirectory*/ undefined) };
+                }
                 if (containsPath(pathOrPattern, targetFilePath)) {
                     const fragment = getRelativePathFromDirectory(pathOrPattern, targetFilePath, /*ignoreCase*/ false);
                     return { moduleFileToTry: getNormalizedAbsolutePath(combinePaths(combinePaths(packageName, exports), fragment), /*currentDirectory*/ undefined) };
@@ -828,51 +836,82 @@ function tryGetModuleNameFromExports(options: CompilerOptions, targetFilePath: s
                 const starPos = pathOrPattern.indexOf("*");
                 const leadingSlice = pathOrPattern.slice(0, starPos);
                 const trailingSlice = pathOrPattern.slice(starPos + 1);
-                if (startsWith(targetFilePath, leadingSlice) && endsWith(targetFilePath, trailingSlice)) {
-                    const starReplacement = targetFilePath.slice(leadingSlice.length, targetFilePath.length - trailingSlice.length);
-                    return { moduleFileToTry: packageName.replace("*", starReplacement) };
-                }
                 if (extensionSwappedTarget && startsWith(extensionSwappedTarget, leadingSlice) && endsWith(extensionSwappedTarget, trailingSlice)) {
                     const starReplacement = extensionSwappedTarget.slice(leadingSlice.length, extensionSwappedTarget.length - trailingSlice.length);
                     return { moduleFileToTry: packageName.replace("*", starReplacement) };
                 }
+                if (startsWith(targetFilePath, leadingSlice) && endsWith(targetFilePath, trailingSlice)) {
+                    const starReplacement = targetFilePath.slice(leadingSlice.length, targetFilePath.length - trailingSlice.length);
+                    return { moduleFileToTry: packageName.replace("*", starReplacement) };
+                }
                 break;
         }
     }
     else if (Array.isArray(exports)) {
-        return forEach(exports, e => tryGetModuleNameFromExports(options, targetFilePath, packageDirectory, packageName, e, conditions));
+        return forEach(exports, e => tryGetModuleNameFromExportsOrImports(options, targetFilePath, packageDirectory, packageName, e, conditions, mode));
     }
     else if (typeof exports === "object" && exports !== null) { // eslint-disable-line no-null/no-null
-        if (allKeysStartWithDot(exports as MapLike<unknown>)) {
-            // sub-mappings
-            // 3 cases:
-            // * directory mappings (legacyish, key ends with / (technically allows index/extension resolution under cjs mode))
-            // * pattern mappings (contains a *)
-            // * exact mappings (no *, does not end with /)
-            return forEach(getOwnKeys(exports as MapLike<unknown>), k => {
-                const subPackageName = getNormalizedAbsolutePath(combinePaths(packageName, k), /*currentDirectory*/ undefined);
-                const mode = endsWith(k, "/") ? MatchingMode.Directory
-                    : stringContains(k, "*") ? MatchingMode.Pattern
-                    : MatchingMode.Exact;
-                return tryGetModuleNameFromExports(options, targetFilePath, packageDirectory, subPackageName, (exports as MapLike<unknown>)[k], conditions, mode);
-            });
-        }
-        else {
-            // conditional mapping
-            for (const key of getOwnKeys(exports as MapLike<unknown>)) {
-                if (key === "default" || conditions.indexOf(key) >= 0 || isApplicableVersionedTypesKey(conditions, key)) {
-                    const subTarget = (exports as MapLike<unknown>)[key];
-                    const result = tryGetModuleNameFromExports(options, targetFilePath, packageDirectory, packageName, subTarget, conditions, mode);
-                    if (result) {
-                        return result;
-                    }
+        // conditional mapping
+        for (const key of getOwnKeys(exports as MapLike<unknown>)) {
+            if (key === "default" || conditions.indexOf(key) >= 0 || isApplicableVersionedTypesKey(conditions, key)) {
+                const subTarget = (exports as MapLike<unknown>)[key];
+                const result = tryGetModuleNameFromExportsOrImports(options, targetFilePath, packageDirectory, packageName, subTarget, conditions, mode);
+                if (result) {
+                    return result;
                 }
             }
         }
     }
     return undefined;
 }
 
+function tryGetModuleNameFromExports(options: CompilerOptions, targetFilePath: string, packageDirectory: string, packageName: string, exports: unknown, conditions: string[]): { moduleFileToTry: string } | undefined {
+    if (typeof exports === "object" && exports !== null && !Array.isArray(exports) && allKeysStartWithDot(exports as MapLike<unknown>)) { // eslint-disable-line no-null/no-null
+        // sub-mappings
+        // 3 cases:
+        // * directory mappings (legacyish, key ends with / (technically allows index/extension resolution under cjs mode))
+        // * pattern mappings (contains a *)
+        // * exact mappings (no *, does not end with /)
+        return forEach(getOwnKeys(exports as MapLike<unknown>), k => {
+            const subPackageName = getNormalizedAbsolutePath(combinePaths(packageName, k), /*currentDirectory*/ undefined);
+            const mode = endsWith(k, "/") ? MatchingMode.Directory
+                : stringContains(k, "*") ? MatchingMode.Pattern
+                : MatchingMode.Exact;
+            return tryGetModuleNameFromExportsOrImports(options, targetFilePath, packageDirectory, subPackageName, (exports as MapLike<unknown>)[k], conditions, mode);
+        });
+    }
+    return tryGetModuleNameFromExportsOrImports(options, targetFilePath, packageDirectory, packageName, exports, conditions, MatchingMode.Exact);
+}
+
+function tryGetModuleNameFromPackageJsonImports(moduleFileName: string, sourceDirectory: Path, options: CompilerOptions, host: ModuleSpecifierResolutionHost, importMode: ResolutionMode) {
+    if (!host.readFile || !getResolvePackageJsonImports(options)) {
+        return undefined;
+    }
+
+    const ancestorDirectoryWithPackageJson = getNearestAncestorDirectoryWithPackageJson(host, sourceDirectory);
+    if (!ancestorDirectoryWithPackageJson) {
+        return undefined;
+    }
+    const packageJsonPath = combinePaths(ancestorDirectoryWithPackageJson, "package.json");
+    const cachedPackageJson = host.getPackageJsonInfoCache?.()?.getPackageJsonInfo(packageJsonPath);
+    if (typeof cachedPackageJson !== "object" && cachedPackageJson !== undefined) {
+        return undefined;
+    }
+    const packageJsonContent = cachedPackageJson?.contents.packageJsonContent || readJson(packageJsonPath, host as { readFile(fileName: string): string | undefined });
+    const imports = (packageJsonContent as any).imports;
+    if (!imports) {
+        return undefined;
+    }
+    const conditions = getConditions(options, importMode === ModuleKind.ESNext);
+    return forEach(getOwnKeys(imports as MapLike<unknown>), k => {
+        if (!startsWith(k, "#") || k === "#" || startsWith(k, "#/")) return undefined;
+        const mode = endsWith(k, "/") ? MatchingMode.Directory
+            : stringContains(k, "*") ? MatchingMode.Pattern
+            : MatchingMode.Exact;
+        return tryGetModuleNameFromExportsOrImports(options, moduleFileName, sourceDirectory, k, (imports as MapLike<unknown>)[k], conditions, mode);
+    })?.moduleFileToTry;
+}
+
 function tryGetModuleNameFromRootDirs(rootDirs: readonly string[], moduleFileName: string, sourceDirectory: string, getCanonicalFileName: (file: string) => string, allowedEndings: readonly ModuleSpecifierEnding[], compilerOptions: CompilerOptions): string | undefined {
     const normalizedTargetPaths = getPathsRelativeToRootDirs(moduleFileName, rootDirs, getCanonicalFileName);
     if (normalizedTargetPaths === undefined) {
@@ -973,10 +1012,7 @@ function tryGetModuleNameAsNodeModule({ path, isRedirect }: ModulePath, { getCan
                     ? tryGetModuleNameFromExports(options, path, packageRootPath, packageName, packageJsonContent.exports, conditions)
                     : undefined;
                 if (fromExports) {
-                    const withJsExtension = !hasTSFileExtension(fromExports.moduleFileToTry)
-                        ? fromExports
-                        : { moduleFileToTry: removeFileExtension(fromExports.moduleFileToTry) + tryGetJSExtensionForFile(fromExports.moduleFileToTry, options) };
-                    return { ...withJsExtension, verbatimFromExports: true };
+                    return { ...fromExports, verbatimFromExports: true };
                 }
                 if (packageJsonContent.exports) {
                     return { moduleFileToTry: path, blockedByExports: true };

tests/cases/fourslash/autoImportPackageJsonExportsSpecifierEndsInTs.ts

@@ -0,0 +1,27 @@
+/// <reference path="fourslash.ts" />
+
+// @module: nodenext
+
+// @Filename: /node_modules/pkg/package.json
+//// {
+////     "name": "pkg",
+////     "version": "1.0.0",
+////     "exports": {
+////       "./something.ts": "./a.js"
+////     }
+////  }
+
+// @Filename: /node_modules/pkg/a.d.ts
+//// export function foo(): void;
+
+// @Filename: /package.json
+//// {
+////     "dependencies": {
+////        "pkg": "*"
+////     }
+////  }
+
+// @Filename: /index.ts
+//// foo/**/
+
+verify.importFixModuleSpecifiers("", ["pkg/something.ts"]);

tests/cases/fourslash/autoImportPackageJsonImportsLength1.ts

@@ -0,0 +1,18 @@
+/// <reference path="fourslash.ts" />
+
+// @module: nodenext
+
+// @Filename: /package.json
+//// {
+////   "imports": {
+////     "#*": "./src/*.ts"
+////   }
+//// }
+
+// @Filename: /src/a/b/c/something.ts
+//// export function something(name: string): any;
+
+// @Filename: /src/a/b/c/d.ts
+//// something/**/
+
+verify.importFixModuleSpecifiers("", ["./something"]);

tests/cases/fourslash/autoImportPackageJsonImportsLength2.ts

@@ -0,0 +1,18 @@
+/// <reference path="fourslash.ts" />
+
+// @module: nodenext
+
+// @Filename: /package.json
+//// {
+////   "imports": {
+////     "#*": "./src/*.ts"
+////   }
+//// }
+
+// @Filename: /src/a/b/c/something.ts
+//// export function something(name: string): any;
+
+// @Filename: /a.ts
+//// something/**/
+
+verify.importFixModuleSpecifiers("", ["#a/b/c/something"]);

tests/cases/fourslash/autoImportPackageJsonImportsPattern.ts

@@ -0,0 +1,18 @@
+/// <reference path="fourslash.ts" />
+
+// @module: nodenext
+
+// @Filename: /package.json
+//// {
+////   "imports": {
+////     "#*": "./src/*"
+////   }
+//// }
+
+// @Filename: /src/something.ts
+//// export function something(name: string): any;
+
+// @Filename: /a.ts
+//// something/**/
+
+verify.importFixModuleSpecifiers("", ["#something.js"]);

tests/cases/fourslash/autoImportPackageJsonImportsPattern_js.ts

@@ -0,0 +1,18 @@
+/// <reference path="fourslash.ts" />
+
+// @module: nodenext
+
+// @Filename: /package.json
+//// {
+////   "imports": {
+////     "#*": "./src/*.js"
+////   }
+//// }
+
+// @Filename: /src/something.ts
+//// export function something(name: string): any;
+
+// @Filename: /a.ts
+//// something/**/
+
+verify.importFixModuleSpecifiers("", ["#something"]);

tests/cases/fourslash/autoImportPackageJsonImportsPattern_js_ts.ts

@@ -0,0 +1,18 @@
+/// <reference path="fourslash.ts" />
+
+// @module: nodenext
+
+// @Filename: /package.json
+//// {
+////   "imports": {
+////     "#*.js": "./src/*.ts"
+////   }
+//// }
+
+// @Filename: /src/something.ts
+//// export function something(name: string): any;
+
+// @Filename: /a.ts
+//// something/**/
+
+verify.importFixModuleSpecifiers("", ["#something.js"]);

tests/cases/fourslash/autoImportPackageJsonImportsPattern_ts.ts

@@ -0,0 +1,18 @@
+/// <reference path="fourslash.ts" />
+
+// @module: nodenext
+
+// @Filename: /package.json
+//// {
+////   "imports": {
+////     "#*": "./src/*.ts"
+////   }
+//// }
+
+// @Filename: /src/something.ts
+//// export function something(name: string): any;
+
+// @Filename: /a.ts
+//// something/**/
+
+verify.importFixModuleSpecifiers("", ["#something"]);

tests/cases/fourslash/autoImportPackageJsonImportsPattern_ts_js.ts

@@ -0,0 +1,18 @@
+/// <reference path="fourslash.ts" />
+
+// @module: nodenext
+
+// @Filename: /package.json
+//// {
+////   "imports": {
+////     "#*.ts": "./src/*.js"
+////   }
+//// }
+
+// @Filename: /src/something.ts
+//// export function something(name: string): any;
+
+// @Filename: /a.ts
+//// something/**/
+
+verify.importFixModuleSpecifiers("", ["#something.ts"]);

tests/cases/fourslash/autoImportPackageJsonImportsPattern_ts_ts.ts

@@ -0,0 +1,18 @@
+/// <reference path="fourslash.ts" />
+
+// @module: nodenext
+
+// @Filename: /package.json
+//// {
+////   "imports": {
+////     "#*.ts": "./src/*.ts"
+////   }
+//// }
+
+// @Filename: /src/something.ts
+//// export function something(name: string): any;
+
+// @Filename: /a.ts
+//// something/**/
+
+verify.importFixModuleSpecifiers("", ["#something.ts"]);

tests/cases/fourslash/autoImportPackageJsonImports_js.ts

@@ -0,0 +1,18 @@
+/// <reference path="fourslash.ts" />
+
+// @module: nodenext
+
+// @Filename: /package.json
+//// {
+////   "imports": {
+////     "#thing": "./src/something.js"
+////   }
+//// }
+
+// @Filename: /src/something.ts
+//// export function something(name: string): any;
+
+// @Filename: /a.ts
+//// something/**/
+
+verify.importFixModuleSpecifiers("", ["#thing"]);