Allow export map entries to remap back to input files for a program

src/compiler/diagnosticMessages.json

@@ -1511,6 +1511,15 @@
         "code": 2207
     },
 
+    "The project root is ambiguous, but is required to resolve export map entry '{0}' in file '{1}'. Supply the `rootDir` compiler option to disambiguate.": {
+        "category": "Error",
+        "code": 2209
+    },
+    "The project root is ambiguous, but is required to resolve import map entry '{0}' in file '{1}'. Supply the `rootDir` compiler option to disambiguate.": {
+        "category": "Error",
+        "code": 2210
+    },
+
     "Duplicate identifier '{0}'.": {
         "category": "Error",
         "code": 2300

src/compiler/program.ts

@@ -1364,6 +1364,36 @@ namespace ts {
 
         return program;
 
+        function addResolutionDiagnostics(list: Diagnostic[] | undefined) {
+            if (!list) return;
+            for (const elem of list) {
+                programDiagnostics.add(elem);
+            }
+        }
+
+        function pullDiagnosticsFromCache(names: string[] | readonly FileReference[], containingFile: SourceFile) {
+            if (!moduleResolutionCache) return;
+            const containingFileName = getNormalizedAbsolutePath(containingFile.originalFileName, currentDirectory);
+            const containingFileMode = !isString(containingFile) ? containingFile.impliedNodeFormat : undefined;
+            const containingDir = getDirectoryPath(containingFileName);
+            const redirectedReference = getRedirectReferenceForResolution(containingFile);
+            let i = 0;
+            for (const n of names) {
+                // mimics logic done in the resolution cache, should be resilient to upgrading it to use `FileReference`s for non-type-reference modal lookups to make it rely on the index in the list less
+                const mode = typeof n === "string" ? getModeForResolutionAtIndex(containingFile, i) : getModeForFileReference(n, containingFileMode);
+                const name = typeof n === "string" ? n : n.fileName;
+                i++;
+                // only nonrelative names hit the cache, and, at least as of right now, only nonrelative names can issue diagnostics
+                // (Since diagnostics are only issued via import or export map lookup)
+                // This may totally change if/when the issue of output paths not mapping to input files is fixed in a broader context
+                // When it is, how we extract diagnostics from the module name resolver will have the be refined - the current cache
+                // APIs wrapping the underlying resolver make it almost impossible to smuggle the diagnostics out in a generalized way
+                if (isExternalModuleNameRelative(name)) continue;
+                const diags = moduleResolutionCache.getOrCreateCacheForModuleName(name, mode, redirectedReference).get(containingDir)?.resolutionDiagnostics;
+                addResolutionDiagnostics(diags);
+            }
+        }
+
         function resolveModuleNamesWorker(moduleNames: string[], containingFile: SourceFile, reusedNames: string[] | undefined): readonly ResolvedModuleFull[] {
             if (!moduleNames.length) return emptyArray;
             const containingFileName = getNormalizedAbsolutePath(containingFile.originalFileName, currentDirectory);
@@ -1374,6 +1404,7 @@ namespace ts {
             performance.mark("afterResolveModule");
             performance.measure("ResolveModule", "beforeResolveModule", "afterResolveModule");
             tracing?.pop();
+            pullDiagnosticsFromCache(moduleNames, containingFile);
             return result;
         }
 

src/compiler/types.ts

@@ -6717,6 +6717,8 @@ namespace ts {
         readonly resolvedModule: ResolvedModuleFull | undefined;
         /* @internal */
         readonly failedLookupLocations: string[];
+        /* @internal */
+        readonly resolutionDiagnostics: Diagnostic[]
     }
 
     export interface ResolvedTypeReferenceDirective {
@@ -6738,6 +6740,8 @@ namespace ts {
     export interface ResolvedTypeReferenceDirectiveWithFailedLookupLocations {
         readonly resolvedTypeReferenceDirective: ResolvedTypeReferenceDirective | undefined;
         readonly failedLookupLocations: string[];
+        /* @internal */
+        resolutionDiagnostics: Diagnostic[]
     }
 
     /* @internal */

src/compiler/utilities.ts

@@ -4387,6 +4387,16 @@ namespace ts {
             Extension.Dts;
     }
 
+    /**
+     * This function is an inverse of `getDeclarationEmitExtensionForPath`.
+     */
+    export function getPossibleOriginalInputExtensionForExtension(path: string) {
+        return fileExtensionIsOneOf(path, [Extension.Dmts, Extension.Mjs, Extension.Mts]) ? [Extension.Mts, Extension.Mjs] :
+            fileExtensionIsOneOf(path, [Extension.Dcts, Extension.Cjs, Extension.Cts]) ? [Extension.Cts, Extension.Cjs]:
+            fileExtensionIsOneOf(path, [`.json.d.ts`]) ? [Extension.Json] :
+            [Extension.Tsx, Extension.Ts, Extension.Jsx, Extension.Js];
+    }
+
     export function outFile(options: CompilerOptions) {
         return options.outFile || options.out;
     }

src/testRunner/unittests/moduleResolution.ts

@@ -215,6 +215,7 @@ namespace ts {
                     extension: Extension.Ts,
                 },
                 failedLookupLocations: [],
+                resolutionDiagnostics: [],
             });
             assert.isDefined(cache.get("/sub"));
             assert.isUndefined(cache.get("/"));
@@ -228,6 +229,7 @@ namespace ts {
                     extension: Extension.Ts,
                 },
                 failedLookupLocations: [],
+                resolutionDiagnostics: [],
             });
             assert.isDefined(cache.get("/sub/dir/foo"));
             assert.isDefined(cache.get("/sub/dir"));
@@ -243,6 +245,7 @@ namespace ts {
                     extension: Extension.Ts,
                 },
                 failedLookupLocations: [],
+                resolutionDiagnostics: [],
             });
             assert.isDefined(cache.get("/foo/bar"));
             assert.isDefined(cache.get("/foo"));
@@ -257,6 +260,7 @@ namespace ts {
                     extension: Extension.Ts,
                 },
                 failedLookupLocations: [],
+                resolutionDiagnostics: [],
             });
             assert.isDefined(cache.get("/foo"));
             assert.isUndefined(cache.get("/"));
@@ -270,6 +274,7 @@ namespace ts {
                     extension: Extension.Ts,
                 },
                 failedLookupLocations: [],
+                resolutionDiagnostics: [],
             });
             assert.isDefined(cache.get("c:/foo"));
             assert.isDefined(cache.get("c:/"));
@@ -279,6 +284,7 @@ namespace ts {
             cache.set("/foo/bar/baz", {
                 resolvedModule: undefined,
                 failedLookupLocations: [],
+                resolutionDiagnostics: [],
             });
             assert.isDefined(cache.get("/foo/bar/baz"));
             assert.isDefined(cache.get("/foo/bar"));

tests/baselines/reference/nodeAllowJsPackageSelfName(module=node16).errors.txt

@@ -1,6 +1,8 @@
+error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 tests/cases/conformance/node/allowJs/index.cjs(2,23): error TS1471: Module 'package' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 
 
+!!! error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 ==== tests/cases/conformance/node/allowJs/index.js (0 errors) ====
     // esm format file
     import * as self from "package";

tests/baselines/reference/nodeAllowJsPackageSelfName(module=nodenext).errors.txt

@@ -1,6 +1,8 @@
+error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 tests/cases/conformance/node/allowJs/index.cjs(2,23): error TS1471: Module 'package' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 
 
+!!! error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 ==== tests/cases/conformance/node/allowJs/index.js (0 errors) ====
     // esm format file
     import * as self from "package";

tests/baselines/reference/nodeModulesAllowJsConditionalPackageExports(module=node16).errors.txt

@@ -1,9 +1,11 @@
+error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 tests/cases/conformance/node/allowJs/index.cjs(3,22): error TS1471: Module 'package/mjs' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.cjs(4,23): error TS1471: Module 'package' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/node_modules/inner/index.d.mts(2,13): error TS2303: Circular definition of import alias 'cjs'.
 tests/cases/conformance/node/allowJs/node_modules/inner/index.d.ts(2,13): error TS2303: Circular definition of import alias 'cjs'.
 
 
+!!! error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 ==== tests/cases/conformance/node/allowJs/index.js (0 errors) ====
     // esm format file
     import * as cjs from "package/cjs";

tests/baselines/reference/nodeModulesAllowJsConditionalPackageExports(module=nodenext).errors.txt

@@ -1,9 +1,11 @@
+error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 tests/cases/conformance/node/allowJs/index.cjs(3,22): error TS1471: Module 'package/mjs' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.cjs(4,23): error TS1471: Module 'package' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/node_modules/inner/index.d.mts(2,13): error TS2303: Circular definition of import alias 'cjs'.
 tests/cases/conformance/node/allowJs/node_modules/inner/index.d.ts(2,13): error TS2303: Circular definition of import alias 'cjs'.
 
 
+!!! error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 ==== tests/cases/conformance/node/allowJs/index.js (0 errors) ====
     // esm format file
     import * as cjs from "package/cjs";

tests/baselines/reference/nodeModulesAllowJsPackageExports(module=node16).errors.txt

@@ -1,3 +1,4 @@
+error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 tests/cases/conformance/node/allowJs/index.cjs(3,22): error TS1471: Module 'package/mjs' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.cjs(4,23): error TS1471: Module 'package' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.cjs(9,23): error TS1471: Module 'inner/mjs' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
@@ -6,6 +7,7 @@ tests/cases/conformance/node/allowJs/node_modules/inner/index.d.ts(2,13): error
 tests/cases/conformance/node/allowJs/node_modules/inner/index.d.ts(3,22): error TS1471: Module 'inner/mjs' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 
 
+!!! error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 ==== tests/cases/conformance/node/allowJs/index.js (0 errors) ====
     // esm format file
     import * as cjs from "package/cjs";

tests/baselines/reference/nodeModulesAllowJsPackageExports(module=nodenext).errors.txt

@@ -1,3 +1,4 @@
+error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 tests/cases/conformance/node/allowJs/index.cjs(3,22): error TS1471: Module 'package/mjs' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.cjs(4,23): error TS1471: Module 'package' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.cjs(9,23): error TS1471: Module 'inner/mjs' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
@@ -6,6 +7,7 @@ tests/cases/conformance/node/allowJs/node_modules/inner/index.d.ts(2,13): error
 tests/cases/conformance/node/allowJs/node_modules/inner/index.d.ts(3,22): error TS1471: Module 'inner/mjs' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 
 
+!!! error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 ==== tests/cases/conformance/node/allowJs/index.js (0 errors) ====
     // esm format file
     import * as cjs from "package/cjs";

tests/baselines/reference/nodeModulesAllowJsPackageImports(module=node16).errors.txt

@@ -1,7 +1,9 @@
+error TS2210: The project root is ambiguous, but is required to resolve import map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 tests/cases/conformance/node/allowJs/index.cjs(3,22): error TS1471: Module '#mjs' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.cjs(4,23): error TS1471: Module '#type' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 
 
+!!! error TS2210: The project root is ambiguous, but is required to resolve import map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 ==== tests/cases/conformance/node/allowJs/index.js (0 errors) ====
     // esm format file
     import * as cjs from "#cjs";

tests/baselines/reference/nodeModulesAllowJsPackageImports(module=nodenext).errors.txt

@@ -1,7 +1,9 @@
+error TS2210: The project root is ambiguous, but is required to resolve import map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 tests/cases/conformance/node/allowJs/index.cjs(3,22): error TS1471: Module '#mjs' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/allowJs/index.cjs(4,23): error TS1471: Module '#type' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 
 
+!!! error TS2210: The project root is ambiguous, but is required to resolve import map entry '.' in file 'tests/cases/conformance/node/allowJs/package.json'. Supply the `rootDir` compiler option to disambiguate.
 ==== tests/cases/conformance/node/allowJs/index.js (0 errors) ====
     // esm format file
     import * as cjs from "#cjs";

tests/baselines/reference/nodeModulesConditionalPackageExports(module=node16).errors.txt

@@ -1,9 +1,11 @@
+error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/package.json'. Supply the `rootDir` compiler option to disambiguate.
 tests/cases/conformance/node/index.cts(3,22): error TS1471: Module 'package/mjs' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.cts(4,23): error TS1471: Module 'package' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/node_modules/inner/index.d.mts(2,13): error TS2303: Circular definition of import alias 'cjs'.
 tests/cases/conformance/node/node_modules/inner/index.d.ts(2,13): error TS2303: Circular definition of import alias 'cjs'.
 
 
+!!! error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/package.json'. Supply the `rootDir` compiler option to disambiguate.
 ==== tests/cases/conformance/node/index.ts (0 errors) ====
     // esm format file
     import * as cjs from "package/cjs";

tests/baselines/reference/nodeModulesConditionalPackageExports(module=nodenext).errors.txt

@@ -1,9 +1,11 @@
+error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/package.json'. Supply the `rootDir` compiler option to disambiguate.
 tests/cases/conformance/node/index.cts(3,22): error TS1471: Module 'package/mjs' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/index.cts(4,23): error TS1471: Module 'package' cannot be imported using this construct. The specifier only resolves to an ES module, which cannot be imported synchronously. Use dynamic import instead.
 tests/cases/conformance/node/node_modules/inner/index.d.mts(2,13): error TS2303: Circular definition of import alias 'cjs'.
 tests/cases/conformance/node/node_modules/inner/index.d.ts(2,13): error TS2303: Circular definition of import alias 'cjs'.
 
 
+!!! error TS2209: The project root is ambiguous, but is required to resolve export map entry '.' in file 'tests/cases/conformance/node/package.json'. Supply the `rootDir` compiler option to disambiguate.
 ==== tests/cases/conformance/node/index.ts (0 errors) ====
     // esm format file
     import * as cjs from "package/cjs";