Correctly resolve imports ending with "." and ".."

src/compiler/moduleNameResolver.ts

@@ -417,7 +417,7 @@ namespace ts {
                     result = searchResult && searchResult.value;
                 }
                 else {
-                    const { path: candidate } = normalizePathAndParts(combinePaths(initialLocationForSecondaryLookup, typeReferenceDirectiveName));
+                    const { path: candidate } = normalizePathForCJSResolution(initialLocationForSecondaryLookup, typeReferenceDirectiveName);
                     result = nodeLoadModuleByRelativeName(Extensions.DtsOnly, candidate, /*onlyRecordFailures*/ false, moduleResolutionState, /*considerPackageJson*/ true);
                 }
                 return resolvedTypeScriptOnly(result);
@@ -1329,12 +1329,26 @@ namespace ts {
                 return { value: resolvedValue && { resolved: resolvedValue, isExternalLibraryImport: true } };
             }
             else {
-                const { path: candidate, parts } = normalizePathAndParts(combinePaths(containingDirectory, moduleName));
+                const { path: candidate, parts } = normalizePathForCJSResolution(containingDirectory, moduleName);
                 const resolved = nodeLoadModuleByRelativeName(extensions, candidate, /*onlyRecordFailures*/ false, state, /*considerPackageJson*/ true);
                 // Treat explicit "node_modules" import as an external library import.
                 return resolved && toSearchResult({ resolved, isExternalLibraryImport: contains(parts, "node_modules") });
             }
         }
+
+    }
+
+    // If you import from "." inside a containing directory "/foo", the result of `normalizePath`
+    // would be "/foo", but this loses the information that `foo` is a directory and we intended
+    // to look inside of it. The Node CommonJS resolution algorithm doesn't call this out
+    // (https://nodejs.org/api/modules.html#all-together), but it seems that module paths ending
+    // in `.` are actually normalized to `./` before proceeding with the resolution algorithm.
+    function normalizePathForCJSResolution(containingDirectory: string, moduleName: string) {
+        const combined = combinePaths(containingDirectory, moduleName);
+        const parts = getPathComponents(combined);
+        const lastPart = lastOrUndefined(parts);
+        const path = lastPart === "." || lastPart === ".." ? ensureTrailingDirectorySeparator(normalizePath(combined)) : normalizePath(combined);
+        return { path, parts };
     }
 
     function realPath(path: string, host: ModuleResolutionHost, traceEnabled: boolean): string {

src/compiler/path.ts

@@ -585,18 +585,6 @@ namespace ts {
         return getCanonicalFileName(nonCanonicalizedPath) as Path;
     }
 
-    export function normalizePathAndParts(path: string): { path: string, parts: string[] } {
-        path = normalizeSlashes(path);
-        const [root, ...parts] = reducePathComponents(getPathComponents(path));
-        if (parts.length) {
-            const joinedParts = root + parts.join(directorySeparator);
-            return { path: hasTrailingDirectorySeparator(path) ? ensureTrailingDirectorySeparator(joinedParts) : joinedParts, parts };
-        }
-        else {
-            return { path: root, parts };
-        }
-    }
-
     //// Path Mutation
 
     /**

tests/baselines/reference/importFromDot.errors.txt

@@ -0,0 +1,14 @@
+tests/cases/conformance/moduleResolution/a/b.ts(1,20): error TS2305: Module '"."' has no exported member 'rootA'.
+
+
+==== tests/cases/conformance/moduleResolution/a.ts (0 errors) ====
+    export const rootA = 0;
+
+==== tests/cases/conformance/moduleResolution/a/index.ts (0 errors) ====
+    export const indexInA = 0;
+
+==== tests/cases/conformance/moduleResolution/a/b.ts (1 errors) ====
+    import { indexInA, rootA } from ".";
+                       ~~~~~
+!!! error TS2305: Module '"."' has no exported member 'rootA'.
+

tests/baselines/reference/importFromDot.js

@@ -0,0 +1,25 @@
+//// [tests/cases/conformance/moduleResolution/importFromDot.ts] ////
+
+//// [a.ts]
+export const rootA = 0;
+
+//// [index.ts]
+export const indexInA = 0;
+
+//// [b.ts]
+import { indexInA, rootA } from ".";
+
+
+//// [a.js]
+"use strict";
+exports.__esModule = true;
+exports.rootA = void 0;
+exports.rootA = 0;
+//// [index.js]
+"use strict";
+exports.__esModule = true;
+exports.indexInA = void 0;
+exports.indexInA = 0;
+//// [b.js]
+"use strict";
+exports.__esModule = true;

tests/baselines/reference/importFromDot.symbols

@@ -0,0 +1,13 @@
+=== tests/cases/conformance/moduleResolution/a.ts ===
+export const rootA = 0;
+>rootA : Symbol(rootA, Decl(a.ts, 0, 12))
+
+=== tests/cases/conformance/moduleResolution/a/index.ts ===
+export const indexInA = 0;
+>indexInA : Symbol(indexInA, Decl(index.ts, 0, 12))
+
+=== tests/cases/conformance/moduleResolution/a/b.ts ===
+import { indexInA, rootA } from ".";
+>indexInA : Symbol(indexInA, Decl(b.ts, 0, 8))
+>rootA : Symbol(rootA, Decl(b.ts, 0, 18))
+

tests/baselines/reference/importFromDot.types

@@ -0,0 +1,15 @@
+=== tests/cases/conformance/moduleResolution/a.ts ===
+export const rootA = 0;
+>rootA : 0
+>0 : 0
+
+=== tests/cases/conformance/moduleResolution/a/index.ts ===
+export const indexInA = 0;
+>indexInA : 0
+>0 : 0
+
+=== tests/cases/conformance/moduleResolution/a/b.ts ===
+import { indexInA, rootA } from ".";
+>indexInA : 0
+>rootA : any
+

tests/baselines/reference/importWithTrailingSlash.errors.txt

@@ -0,0 +1,26 @@
+/a/b/test.ts(3,3): error TS2339: Property 'a' does not exist on type '{ aIndex: number; }'.
+/a/test.ts(3,3): error TS2339: Property 'a' does not exist on type '{ aIndex: number; }'.
+
+
+==== /a.ts (0 errors) ====
+    export default { a: 0 };
+
+==== /a/index.ts (0 errors) ====
+    export default { aIndex: 0 };
+
+==== /a/test.ts (1 errors) ====
+    import a from ".";
+    import aIndex from "./";
+    a.a;
+      ~
+!!! error TS2339: Property 'a' does not exist on type '{ aIndex: number; }'.
+    aIndex.aIndex;
+
+==== /a/b/test.ts (1 errors) ====
+    import a from "..";
+    import aIndex from "../";
+    a.a;
+      ~
+!!! error TS2339: Property 'a' does not exist on type '{ aIndex: number; }'.
+    aIndex.aIndex;
+

tests/baselines/reference/importWithTrailingSlash.symbols

@@ -14,9 +14,7 @@ import aIndex from "./";
 >aIndex : Symbol(aIndex, Decl(test.ts, 1, 6))
 
 a.a;
->a.a : Symbol(a, Decl(a.ts, 0, 16))
 >a : Symbol(a, Decl(test.ts, 0, 6))
->a : Symbol(a, Decl(a.ts, 0, 16))
 
 aIndex.aIndex;
 >aIndex.aIndex : Symbol(aIndex, Decl(index.ts, 0, 16))
@@ -31,9 +29,7 @@ import aIndex from "../";
 >aIndex : Symbol(aIndex, Decl(test.ts, 1, 6))
 
 a.a;
->a.a : Symbol(a, Decl(a.ts, 0, 16))
 >a : Symbol(a, Decl(test.ts, 0, 6))
->a : Symbol(a, Decl(a.ts, 0, 16))
 
 aIndex.aIndex;
 >aIndex.aIndex : Symbol(aIndex, Decl(index.ts, 0, 16))

tests/baselines/reference/importWithTrailingSlash.trace.json

@@ -1,20 +1,22 @@
 [
     "======== Resolving module '.' from '/a/test.ts'. ========",
     "Explicitly specified module resolution kind: 'NodeJs'.",
-    "Loading module as file / folder, candidate module location '/a', target file type 'TypeScript'.",
-    "File '/a.ts' exist - use it as a name resolution result.",
-    "======== Module name '.' was successfully resolved to '/a.ts'. ========",
+    "Loading module as file / folder, candidate module location '/a/', target file type 'TypeScript'.",
+    "File '/a/package.json' does not exist.",
+    "File '/a/index.ts' exist - use it as a name resolution result.",
+    "======== Module name '.' was successfully resolved to '/a/index.ts'. ========",
     "======== Resolving module './' from '/a/test.ts'. ========",
     "Explicitly specified module resolution kind: 'NodeJs'.",
     "Loading module as file / folder, candidate module location '/a/', target file type 'TypeScript'.",
-    "File '/a/package.json' does not exist.",
+    "File '/a/package.json' does not exist according to earlier cached lookups.",
     "File '/a/index.ts' exist - use it as a name resolution result.",
     "======== Module name './' was successfully resolved to '/a/index.ts'. ========",
     "======== Resolving module '..' from '/a/b/test.ts'. ========",
     "Explicitly specified module resolution kind: 'NodeJs'.",
-    "Loading module as file / folder, candidate module location '/a', target file type 'TypeScript'.",
-    "File '/a.ts' exist - use it as a name resolution result.",
-    "======== Module name '..' was successfully resolved to '/a.ts'. ========",
+    "Loading module as file / folder, candidate module location '/a/', target file type 'TypeScript'.",
+    "File '/a/package.json' does not exist according to earlier cached lookups.",
+    "File '/a/index.ts' exist - use it as a name resolution result.",
+    "======== Module name '..' was successfully resolved to '/a/index.ts'. ========",
     "======== Resolving module '../' from '/a/b/test.ts'. ========",
     "Explicitly specified module resolution kind: 'NodeJs'.",
     "Loading module as file / folder, candidate module location '/a/', target file type 'TypeScript'.",

tests/baselines/reference/importWithTrailingSlash.types

@@ -12,15 +12,15 @@ export default { aIndex: 0 };
 
 === /a/test.ts ===
 import a from ".";
->a : { a: number; }
+>a : { aIndex: number; }
 
 import aIndex from "./";
 >aIndex : { aIndex: number; }
 
 a.a;
->a.a : number
->a : { a: number; }
->a : number
+>a.a : any
+>a : { aIndex: number; }
+>a : any
 
 aIndex.aIndex;
 >aIndex.aIndex : number
@@ -29,15 +29,15 @@ aIndex.aIndex;
 
 === /a/b/test.ts ===
 import a from "..";
->a : { a: number; }
+>a : { aIndex: number; }
 
 import aIndex from "../";
 >aIndex : { aIndex: number; }
 
 a.a;
->a.a : number
->a : { a: number; }
->a : number
+>a.a : any
+>a : { aIndex: number; }
+>a : any
 
 aIndex.aIndex;
 >aIndex.aIndex : number

tests/baselines/reference/tsserver/projectReferences/find-refs-to-decl-in-other-proj-when-proj-is-loaded-and-refd-proj-loading-is-disabled-and-proj-ref-redirects-are-disabled-and-a-decl-map-is-missing.js

@@ -78,8 +78,6 @@ Creating configuration project /user/username/projects/myproject/b/tsconfig.json
 Plugins were requested but not running in environment that supports 'require'. Nothing will be loaded
 FileWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b/index.ts 500 undefined WatchType: Closed Script info
 Starting updateGraphWorker: Project: /user/username/projects/myproject/b/tsconfig.json
-DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
-Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Missing file

tests/baselines/reference/tsserver/projectReferences/find-refs-to-decl-in-other-proj-when-proj-is-loaded-and-refd-proj-loading-is-disabled-and-proj-ref-redirects-are-disabled-and-a-decl-map-is-present.js

@@ -78,8 +78,6 @@ Creating configuration project /user/username/projects/myproject/b/tsconfig.json
 Plugins were requested but not running in environment that supports 'require'. Nothing will be loaded
 FileWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b/index.ts 500 undefined WatchType: Closed Script info
 Starting updateGraphWorker: Project: /user/username/projects/myproject/b/tsconfig.json
-DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
-Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Missing file

tests/baselines/reference/tsserver/projectReferences/find-refs-to-decl-in-other-proj-when-proj-is-loaded-and-refd-proj-loading-is-disabled-and-proj-ref-redirects-are-enabled-and-a-decl-map-is-missing.js

@@ -77,8 +77,6 @@ For info: /user/username/projects/myproject/b/helper.ts :: Config file name: /us
 Creating configuration project /user/username/projects/myproject/b/tsconfig.json
 Plugins were requested but not running in environment that supports 'require'. Nothing will be loaded
 Starting updateGraphWorker: Project: /user/username/projects/myproject/b/tsconfig.json
-DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
-Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Missing file

tests/baselines/reference/tsserver/projectReferences/find-refs-to-decl-in-other-proj-when-proj-is-loaded-and-refd-proj-loading-is-disabled-and-proj-ref-redirects-are-enabled-and-a-decl-map-is-present.js

@@ -77,8 +77,6 @@ For info: /user/username/projects/myproject/b/helper.ts :: Config file name: /us
 Creating configuration project /user/username/projects/myproject/b/tsconfig.json
 Plugins were requested but not running in environment that supports 'require'. Nothing will be loaded
 Starting updateGraphWorker: Project: /user/username/projects/myproject/b/tsconfig.json
-DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
-Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Missing file

tests/baselines/reference/tsserver/projectReferences/find-refs-to-decl-in-other-proj-when-proj-is-loaded-and-refd-proj-loading-is-enabled-and-proj-ref-redirects-are-disabled-and-a-decl-map-is-missing.js

@@ -78,8 +78,6 @@ Creating configuration project /user/username/projects/myproject/b/tsconfig.json
 Plugins were requested but not running in environment that supports 'require'. Nothing will be loaded
 FileWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b/index.ts 500 undefined WatchType: Closed Script info
 Starting updateGraphWorker: Project: /user/username/projects/myproject/b/tsconfig.json
-DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
-Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Missing file

tests/baselines/reference/tsserver/projectReferences/find-refs-to-decl-in-other-proj-when-proj-is-loaded-and-refd-proj-loading-is-enabled-and-proj-ref-redirects-are-disabled-and-a-decl-map-is-present.js

@@ -78,8 +78,6 @@ Creating configuration project /user/username/projects/myproject/b/tsconfig.json
 Plugins were requested but not running in environment that supports 'require'. Nothing will be loaded
 FileWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b/index.ts 500 undefined WatchType: Closed Script info
 Starting updateGraphWorker: Project: /user/username/projects/myproject/b/tsconfig.json
-DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
-Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Missing file

tests/baselines/reference/tsserver/projectReferences/find-refs-to-decl-in-other-proj-when-proj-is-loaded-and-refd-proj-loading-is-enabled-and-proj-ref-redirects-are-enabled-and-a-decl-map-is-missing.js

@@ -77,8 +77,6 @@ For info: /user/username/projects/myproject/b/helper.ts :: Config file name: /us
 Creating configuration project /user/username/projects/myproject/b/tsconfig.json
 Plugins were requested but not running in environment that supports 'require'. Nothing will be loaded
 Starting updateGraphWorker: Project: /user/username/projects/myproject/b/tsconfig.json
-DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
-Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Missing file

tests/baselines/reference/tsserver/projectReferences/find-refs-to-decl-in-other-proj-when-proj-is-loaded-and-refd-proj-loading-is-enabled-and-proj-ref-redirects-are-enabled-and-a-decl-map-is-present.js

@@ -77,8 +77,6 @@ For info: /user/username/projects/myproject/b/helper.ts :: Config file name: /us
 Creating configuration project /user/username/projects/myproject/b/tsconfig.json
 Plugins were requested but not running in environment that supports 'require'. Nothing will be loaded
 Starting updateGraphWorker: Project: /user/username/projects/myproject/b/tsconfig.json
-DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
-Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b 0 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Failed Lookup Locations
 FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 500 undefined Project: /user/username/projects/myproject/b/tsconfig.json WatchType: Missing file