fix: logic

lib/util/entrypoints.js

@@ -84,7 +84,7 @@ module.exports.processExportsField = function processExportsField(
 	exportsField
 ) {
 	return createFieldProcessor(
-		buildExportsFieldPathTree(exportsField),
+		buildExportsField(exportsField),
 		assertExportsFieldRequest,
 		assertExportTarget
 	);
@@ -98,7 +98,7 @@ module.exports.processImportsField = function processImportsField(
 	importsField
 ) {
 	return createFieldProcessor(
-		buildImportsFieldPathTree(importsField),
+		buildImportsField(importsField),
 		assertImportsFieldRequest,
 		assertImportTarget
 	);
@@ -295,15 +295,25 @@ function findMatch(request, field) {
 					request.length - patternTrailer.length
 				);
 			}
-		} else if (
-			// For `./foo/` or `./`
+		}
+		// For legacy `./foo/`
+		else if (
 			key[key.length - 1] === "/" &&
 			request.startsWith(key) &&
 			patternKeyCompare(bestMatch, key) === 1
 		) {
 			bestMatch = key;
 			bestMatchSubpath = request.slice(key.length);
 		}
+		// For legacy `./`
+		else if (
+			key === "./" &&
+			patternKeyCompare(bestMatch, key) === 1 &&
+			request.length > 0
+		) {
+			bestMatch = key;
+			bestMatchSubpath = request.slice(key.length - 2);
+		}
 	}
 
 	if (bestMatch === "") return null;
@@ -458,7 +468,7 @@ function conditionalMapping(conditionalMapping_, conditionNames) {
  * @param {ExportsField} field exports field
  * @returns {ExportsField} normalized exports field
  */
-function buildExportsFieldPathTree(field) {
+function buildExportsField(field) {
 	// handle syntax sugar, if exports field is direct mapping for "."
 	if (typeof field === "string" || Array.isArray(field)) {
 		return { "": field };
@@ -509,7 +519,8 @@ function buildExportsFieldPathTree(field) {
 			);
 		}
 
-		newField[key.slice(2)] = field[key];
+		// Keep "./" for legacy `{ "./": "./" }`
+		newField[key.slice(2) || "./"] = field[key];
 	}
 
 	return newField;
@@ -519,7 +530,7 @@ function buildExportsFieldPathTree(field) {
  * @param {ImportsField} field imports field
  * @returns {ImportsField} normalized imports field
  */
-function buildImportsFieldPathTree(field) {
+function buildImportsField(field) {
 	const keys = Object.keys(field);
 	const newField = /** @type {ImportsField} */ ({});