Error on package.json conditional exports fallback lookups

src/compiler/diagnosticMessages.json

@@ -8519,5 +8519,9 @@
     "'{0}' is not a valid meta-property for keyword 'import'. Did you mean 'meta' or 'defer'?": {
         "category": "Error",
         "code": 18061
+    },
+    "This import could not be resolved using the '{0}' exports condition in its package.json. Types were found using the condition '{1}', but this lower-priority condition will not be used at runtime. This is a bug in the '{2}' library's typings configuration.": {
+        "category": "Error",
+        "code": 18062
     }
 }

src/compiler/moduleNameResolver.ts

@@ -37,7 +37,6 @@ import {
     forEachAncestorDirectory,
     formatMessage,
     getAllowImportingTsExtensions,
-    getAllowJSCompilerOption,
     getAnyExtensionFromPath,
     getBaseFileName,
     GetCanonicalFileName,
@@ -327,6 +326,8 @@ export interface ModuleResolutionState {
     isConfigLookup: boolean;
     candidateIsFromPackageJsonField: boolean;
     resolvedPackageDirectory: boolean;
+    /** When beginning a fallback lookup in exports conditions, value is set to the object containing the conditions */
+    inFallbackConditionsLookup?: object;
 }
 
 /** Just the fields that we use for module resolution.
@@ -2586,26 +2587,7 @@ function loadModuleFromSelfNameReference(extensions: Extensions, moduleName: str
     }
     const trailingParts = parts.slice(nameParts.length);
     const subpath = !length(trailingParts) ? "." : `.${directorySeparator}${trailingParts.join(directorySeparator)}`;
-    // Maybe TODO: splitting extensions into two priorities should be unnecessary, except
-    // https://github.com/microsoft/TypeScript/issues/50762 makes the behavior different.
-    // As long as that bug exists, we need to do two passes here in self-name loading
-    // in order to be consistent with (non-self) library-name loading in
-    // `loadModuleFromNearestNodeModulesDirectoryWorker`, which uses two passes in order
-    // to prioritize `@types` packages higher up the directory tree over untyped
-    // implementation packages. See the selfNameModuleAugmentation.ts test for why this
-    // matters.
-    //
-    // However, there's an exception. If the user has `allowJs` and `declaration`, we need
-    // to ensure that self-name imports of their own package can resolve back to their
-    // input JS files via `tryLoadInputFileForPath` at a higher priority than their output
-    // declaration files, so we need to do a single pass with all extensions for that case.
-    if (getAllowJSCompilerOption(state.compilerOptions) && !pathContainsNodeModules(directory)) {
-        return loadModuleFromExports(scope, extensions, subpath, state, cache, redirectedReference);
-    }
-    const priorityExtensions = extensions & (Extensions.TypeScript | Extensions.Declaration);
-    const secondaryExtensions = extensions & ~(Extensions.TypeScript | Extensions.Declaration);
-    return loadModuleFromExports(scope, priorityExtensions, subpath, state, cache, redirectedReference)
-        || loadModuleFromExports(scope, secondaryExtensions, subpath, state, cache, redirectedReference);
+    return loadModuleFromExports(scope, extensions, subpath, state, cache, redirectedReference);
 }
 
 function loadModuleFromExports(scope: PackageJsonInfo, extensions: Extensions, subpath: string, state: ModuleResolutionState, cache: ModuleResolutionCache | undefined, redirectedReference: ResolvedProjectReference | undefined): SearchResult<Resolved> {
@@ -2806,6 +2788,7 @@ function getLoadModuleFromTargetExportOrImport(extensions: Extensions, state: Mo
         else if (typeof target === "object" && target !== null) { // eslint-disable-line no-restricted-syntax
             if (!Array.isArray(target)) {
                 traceIfEnabled(state, Diagnostics.Entering_conditional_exports);
+                const saveInFallbackConditionsLookup = state.inFallbackConditionsLookup;
                 for (const condition of getOwnKeys(target as MapLike<unknown>)) {
                     if (condition === "default" || state.conditions.includes(condition) || isApplicableVersionedTypesKey(state.conditions, condition)) {
                         traceIfEnabled(state, Diagnostics.Matched_0_condition_1, isImports ? "imports" : "exports", condition);
@@ -2814,17 +2797,33 @@ function getLoadModuleFromTargetExportOrImport(extensions: Extensions, state: Mo
                         if (result) {
                             traceIfEnabled(state, Diagnostics.Resolved_under_condition_0, condition);
                             traceIfEnabled(state, Diagnostics.Exiting_conditional_exports);
+                            if (state.inFallbackConditionsLookup === target) {
+                                const firstMatchingCondition = getOwnKeys(target as MapLike<unknown>).find(c => c === "default" || state.conditions.includes(c) || isApplicableVersionedTypesKey(state.conditions, c))!;
+                                const packageName = scope.contents.packageJsonContent.name || scope.packageDirectory;
+                                state.reportDiagnostic(createCompilerDiagnostic(
+                                    Diagnostics.This_import_could_not_be_resolved_using_the_0_exports_condition_in_its_package_json_Types_were_found_using_the_condition_1_but_this_lower_priority_condition_will_not_be_used_at_runtime_This_is_a_bug_in_the_2_library_s_typings_configuration,
+                                    firstMatchingCondition,
+                                    condition,
+                                    packageName,
+                                ));
+                            }
                             return result;
                         }
                         else {
                             traceIfEnabled(state, Diagnostics.Failed_to_resolve_under_condition_0, condition);
+                            if (isImports) {
+                                // Don't use fallback conditions for imports, since the user can fix their own package.json
+                                return { value: undefined };
+                            }
+                            state.inFallbackConditionsLookup = target;
                         }
                     }
                     else {
                         traceIfEnabled(state, Diagnostics.Saw_non_matching_condition_0, condition);
                     }
                 }
                 traceIfEnabled(state, Diagnostics.Exiting_conditional_exports);
+                state.inFallbackConditionsLookup = saveInFallbackConditionsLookup;
                 return undefined;
             }
             else {

tests/baselines/reference/conditionalExportsResolutionFallback(moduleresolution=bundler).errors.txt

@@ -0,0 +1,25 @@
+error TS18062: This import could not be resolved using the 'import' exports condition in its package.json. Types were found using the condition 'types', but this lower-priority condition will not be used at runtime. This is a bug in the 'dep' library's typings configuration.
+
+
+!!! error TS18062: This import could not be resolved using the 'import' exports condition in its package.json. Types were found using the condition 'types', but this lower-priority condition will not be used at runtime. This is a bug in the 'dep' library's typings configuration.
+==== /node_modules/dep/package.json (0 errors) ====
+    {
+      "name": "dep",
+      "version": "1.0.0",
+      "exports": {
+        ".": {
+            "import": "./dist/index.mjs",
+            "require": "./dist/index.js",
+            "types": "./dist/index.d.ts"
+        }
+      }
+    }
+
+==== /node_modules/dep/dist/index.d.ts (0 errors) ====
+    export {};
+
+==== /node_modules/dep/dist/index.mjs (0 errors) ====
+    export {};
+
+==== /index.mts (0 errors) ====
+    import {} from "dep";

tests/baselines/reference/conditionalExportsResolutionFallback(moduleresolution=node16).errors.txt

@@ -1,7 +1,9 @@
 error TS5110: Option 'module' must be set to 'Node16' when option 'moduleResolution' is set to 'Node16'.
+error TS18062: This import could not be resolved using the 'import' exports condition in its package.json. Types were found using the condition 'types', but this lower-priority condition will not be used at runtime. This is a bug in the 'dep' library's typings configuration.
 
 
 !!! error TS5110: Option 'module' must be set to 'Node16' when option 'moduleResolution' is set to 'Node16'.
+!!! error TS18062: This import could not be resolved using the 'import' exports condition in its package.json. Types were found using the condition 'types', but this lower-priority condition will not be used at runtime. This is a bug in the 'dep' library's typings configuration.
 ==== /node_modules/dep/package.json (0 errors) ====
     {
       "name": "dep",
@@ -22,9 +24,4 @@ error TS5110: Option 'module' must be set to 'Node16' when option 'moduleResolut
     export {};
 
 ==== /index.mts (0 errors) ====
-    import {} from "dep";
-    // Should be an untyped resolution to dep/dist/index.mjs,
-    // but the first search is only for TS files, and when
-    // there's no dist/index.d.mts, it continues looking for
-    // matching conditions and resolves via `types`.
-
+    import {} from "dep";

tests/baselines/reference/conditionalExportsResolutionFallback(moduleresolution=nodenext).errors.txt

@@ -1,7 +1,9 @@
 error TS5110: Option 'module' must be set to 'NodeNext' when option 'moduleResolution' is set to 'NodeNext'.
+error TS18062: This import could not be resolved using the 'import' exports condition in its package.json. Types were found using the condition 'types', but this lower-priority condition will not be used at runtime. This is a bug in the 'dep' library's typings configuration.
 
 
 !!! error TS5110: Option 'module' must be set to 'NodeNext' when option 'moduleResolution' is set to 'NodeNext'.
+!!! error TS18062: This import could not be resolved using the 'import' exports condition in its package.json. Types were found using the condition 'types', but this lower-priority condition will not be used at runtime. This is a bug in the 'dep' library's typings configuration.
 ==== /node_modules/dep/package.json (0 errors) ====
     {
       "name": "dep",
@@ -22,9 +24,4 @@ error TS5110: Option 'module' must be set to 'NodeNext' when option 'moduleResol
     export {};
 
 ==== /index.mts (0 errors) ====
-    import {} from "dep";
-    // Should be an untyped resolution to dep/dist/index.mjs,
-    // but the first search is only for TS files, and when
-    // there's no dist/index.d.mts, it continues looking for
-    // matching conditions and resolves via `types`.
-
+    import {} from "dep";

tests/baselines/reference/selfNameModuleAugmentation.errors.txt

@@ -0,0 +1,38 @@
+error TS18062: This import could not be resolved using the 'import' exports condition in its package.json. Types were found using the condition 'default', but this lower-priority condition will not be used at runtime. This is a bug in the 'acorn-walk' library's typings configuration.
+/index.ts(1,10): error TS2305: Module '"acorn-walk"' has no exported member 'simple'.
+
+
+!!! error TS18062: This import could not be resolved using the 'import' exports condition in its package.json. Types were found using the condition 'default', but this lower-priority condition will not be used at runtime. This is a bug in the 'acorn-walk' library's typings configuration.
+==== /node_modules/acorn-walk/package.json (0 errors) ====
+    {
+      "name": "acorn-walk",
+      "version": "8.2.0",
+      "main": "dist/walk.js",
+      "types": "dist/walk.d.ts",
+      "exports": {
+        ".": [
+          {
+              "import": "./dist/walk.mjs",
+              "require": "./dist/walk.js",
+              "default": "./dist/walk.js"
+          },
+          "./dist/walk.js"
+        ],
+        "./package.json": "./package.json"
+      }
+    }
+
+==== /node_modules/acorn-walk/dist/walk.d.ts (0 errors) ====
+    export {};
+    declare module 'acorn-walk' {
+      export function simple(node: any, visitors: any, base?: any, state?: any): any;
+    }
+
+==== /node_modules/acorn-walk/dist/walk.mjs (0 errors) ====
+    export {};
+
+==== /index.ts (1 errors) ====
+    import { simple } from 'acorn-walk';
+             ~~~~~~
+!!! error TS2305: Module '"acorn-walk"' has no exported member 'simple'.
+

tests/baselines/reference/selfNameModuleAugmentation.symbols

@@ -3,7 +3,7 @@
 === /node_modules/acorn-walk/dist/walk.d.ts ===
 export {};
 declare module 'acorn-walk' {
->'acorn-walk' : Symbol("/node_modules/acorn-walk/dist/walk", Decl(walk.d.ts, 0, 0), Decl(walk.d.ts, 0, 10))
+>'acorn-walk' : Symbol("/node_modules/acorn-walk/dist/walk", Decl(walk.mjs, 0, 0), Decl(walk.d.ts, 0, 10))
 
   export function simple(node: any, visitors: any, base?: any, state?: any): any;
 >simple : Symbol(simple, Decl(walk.d.ts, 1, 29))

tests/baselines/reference/selfNameModuleAugmentation.trace.json

@@ -12,18 +12,11 @@
     "File name '/node_modules/acorn-walk/dist/walk.mjs' has a '.mjs' extension - stripping it.",
     "File '/node_modules/acorn-walk/dist/walk.mts' does not exist.",
     "File '/node_modules/acorn-walk/dist/walk.d.mts' does not exist.",
-    "Failed to resolve under condition 'import'.",
-    "Saw non-matching condition 'require'.",
-    "Matched 'exports' condition 'default'.",
-    "Using 'exports' subpath '.' with target './dist/walk.js'.",
-    "File name '/node_modules/acorn-walk/dist/walk.js' has a '.js' extension - stripping it.",
-    "File '/node_modules/acorn-walk/dist/walk.ts' does not exist.",
-    "File '/node_modules/acorn-walk/dist/walk.tsx' does not exist.",
-    "File '/node_modules/acorn-walk/dist/walk.d.ts' exists - use it as a name resolution result.",
+    "File '/node_modules/acorn-walk/dist/walk.mjs' exists - use it as a name resolution result.",
     "'package.json' does not have a 'peerDependencies' field.",
-    "Resolved under condition 'default'.",
+    "Resolved under condition 'import'.",
     "Exiting conditional exports.",
-    "======== Module name 'acorn-walk' was successfully resolved to '/node_modules/acorn-walk/dist/walk.d.ts' with Package ID 'acorn-walk/dist/walk.d.ts@8.2.0'. ========",
+    "======== Module name 'acorn-walk' was successfully resolved to '/node_modules/acorn-walk/dist/walk.mjs' with Package ID 'acorn-walk/dist/walk.mjs@8.2.0'. ========",
     "======== Resolving module 'acorn-walk' from '/index.ts'. ========",
     "Explicitly specified module resolution kind: 'Bundler'.",
     "Resolving in CJS mode with conditions 'import', 'types'.",

tests/baselines/reference/selfNameModuleAugmentation.types

@@ -10,9 +10,13 @@ declare module 'acorn-walk' {
 >simple : (node: any, visitors: any, base?: any, state?: any) => any
 >       : ^    ^^   ^^        ^^   ^^    ^^^   ^^     ^^^   ^^^^^   
 >node : any
+>     : ^^^
 >visitors : any
+>         : ^^^
 >base : any
+>     : ^^^
 >state : any
+>      : ^^^
 }
 
 === /node_modules/acorn-walk/dist/walk.mjs ===
@@ -21,6 +25,6 @@ export {};
 
 === /index.ts ===
 import { simple } from 'acorn-walk';
->simple : (node: any, visitors: any, base?: any, state?: any) => any
->       : ^    ^^   ^^        ^^   ^^    ^^^   ^^     ^^^   ^^^^^   
+>simple : any
+>       : ^^^
 

tests/baselines/reference/tsserver/fourslashServer/pathCompletionsPackageJsonImportsSrcNoDistWildcard2.js

@@ -1118,10 +1118,6 @@ Info seq  [hh:mm:ss:mss] DirectoryWatcher:: Added:: WatchInfo: /home/src/workspa
 Info seq  [hh:mm:ss:mss] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /home/src/workspaces/project/src 1 undefined Project: /home/src/workspaces/project/tsconfig.json WatchType: Failed Lookup Locations
 Info seq  [hh:mm:ss:mss] DirectoryWatcher:: Added:: WatchInfo: /home/src/workspaces/project/dist 1 undefined Project: /home/src/workspaces/project/tsconfig.json WatchType: Failed Lookup Locations
 Info seq  [hh:mm:ss:mss] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /home/src/workspaces/project/dist 1 undefined Project: /home/src/workspaces/project/tsconfig.json WatchType: Failed Lookup Locations
-Info seq  [hh:mm:ss:mss] DirectoryWatcher:: Added:: WatchInfo: /home/src/workspaces/project/node_modules 1 undefined Project: /home/src/workspaces/project/tsconfig.json WatchType: Failed Lookup Locations
-Info seq  [hh:mm:ss:mss] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /home/src/workspaces/project/node_modules 1 undefined Project: /home/src/workspaces/project/tsconfig.json WatchType: Failed Lookup Locations
-Info seq  [hh:mm:ss:mss] DirectoryWatcher:: Added:: WatchInfo: /home/src/workspaces/node_modules 1 undefined Project: /home/src/workspaces/project/tsconfig.json WatchType: Failed Lookup Locations
-Info seq  [hh:mm:ss:mss] Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /home/src/workspaces/node_modules 1 undefined Project: /home/src/workspaces/project/tsconfig.json WatchType: Failed Lookup Locations
 Info seq  [hh:mm:ss:mss] Finishing updateGraphWorker: Project: /home/src/workspaces/project/tsconfig.json projectStateVersion: 2 projectProgramVersion: 1 structureChanged: true structureIsReused:: SafeModules Elapsed:: *ms
 Info seq  [hh:mm:ss:mss] Project '/home/src/workspaces/project/tsconfig.json' (Configured)
 Info seq  [hh:mm:ss:mss] 	Files (2)
@@ -1183,7 +1179,6 @@ watchedFiles::
 watchedDirectoriesRecursive::
 /home/src/workspaces/node_modules:
   {}
-  {} *new*
 /home/src/workspaces/node_modules/@types:
   {}
   {}
@@ -1193,7 +1188,6 @@ watchedDirectoriesRecursive::
   {}
 /home/src/workspaces/project/node_modules:
   {}
-  {} *new*
 /home/src/workspaces/project/node_modules/@types:
   {}
   {}

tests/cases/conformance/moduleResolution/conditionalExportsResolutionFallback.ts

@@ -27,8 +27,4 @@ export {};
 export {};
 
 // @Filename: /index.mts
-import {} from "dep";
-// Should be an untyped resolution to dep/dist/index.mjs,
-// but the first search is only for TS files, and when
-// there's no dist/index.d.mts, it continues looking for
-// matching conditions and resolves via `types`.
+import {} from "dep";