Merge pull request #25433 from a-tarasyuk/bug/24839-give-a-better-error-message-for-using-import-as-a-type

24839 - Give a better error message for using import as a type

Author: mhegazy

src/compiler/checker.ts

@@ -9264,7 +9264,12 @@ namespace ts {
                         resolveImportSymbolType(node, links, moduleSymbol, targetMeaning);
                     }
                     else {
-                        error(node, targetMeaning === SymbolFlags.Value ? Diagnostics.Module_0_does_not_refer_to_a_value_but_is_used_as_a_value_here : Diagnostics.Module_0_does_not_refer_to_a_type_but_is_used_as_a_type_here, moduleName);
+                        const errorMessage = targetMeaning === SymbolFlags.Value
+                            ? Diagnostics.Module_0_does_not_refer_to_a_value_but_is_used_as_a_value_here
+                            : Diagnostics.Module_0_does_not_refer_to_a_type_but_is_used_as_a_type_here_Did_you_mean_typeof_import_0;
+
+                        error(node, errorMessage, moduleName);
+
                         links.resolvedSymbol = unknownSymbol;
                         links.resolvedType = errorType;
                     }

src/compiler/diagnosticMessages.json

@@ -971,7 +971,7 @@
         "category": "Error",
         "code": 1339
     },
-    "Module '{0}' does not refer to a type, but is used as a type here.": {
+    "Module '{0}' does not refer to a type, but is used as a type here. Did you mean 'typeof import('{0}')'?": {
         "category": "Error",
         "code": 1340
     },

src/services/codefixes/fixAddModuleReferTypeMissingTypeof.ts

@@ -2,7 +2,8 @@
 namespace ts.codefix {
     const fixIdAddMissingTypeof = "fixAddModuleReferTypeMissingTypeof";
     const fixId = fixIdAddMissingTypeof;
-    const errorCodes = [Diagnostics.Module_0_does_not_refer_to_a_type_but_is_used_as_a_type_here.code];
+    const errorCodes = [Diagnostics.Module_0_does_not_refer_to_a_type_but_is_used_as_a_type_here_Did_you_mean_typeof_import_0.code];
+
     registerCodeFix({
         errorCodes,
         getCodeActions: context => {

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -5073,7 +5073,7 @@ declare namespace ts {
         An_index_signature_parameter_type_cannot_be_a_union_type_Consider_using_a_mapped_object_type_instead: DiagnosticMessage;
         infer_declarations_are_only_permitted_in_the_extends_clause_of_a_conditional_type: DiagnosticMessage;
         Module_0_does_not_refer_to_a_value_but_is_used_as_a_value_here: DiagnosticMessage;
-        Module_0_does_not_refer_to_a_type_but_is_used_as_a_type_here: DiagnosticMessage;
+        Module_0_does_not_refer_to_a_type_but_is_used_as_a_type_here_Did_you_mean_typeof_import_0: DiagnosticMessage;
         Type_arguments_cannot_be_used_here: DiagnosticMessage;
         The_import_meta_meta_property_is_only_allowed_using_ESNext_for_the_target_and_module_compiler_options: DiagnosticMessage;
         Duplicate_identifier_0: DiagnosticMessage;

tests/baselines/reference/importUsedAsTypeWithErrors.errors.txt

@@ -0,0 +1,13 @@
+tests/cases/compiler/main.ts(1,17): error TS1340: Module './test' does not refer to a type, but is used as a type here. Did you mean 'typeof import('./test')'?
+
+
+==== tests/cases/compiler/test.ts (0 errors) ====
+    export interface T {
+        value: string
+    }
+    
+==== tests/cases/compiler/main.ts (1 errors) ====
+    export const a: import("./test") = null;
+                    ~~~~~~~~~~~~~~~~
+!!! error TS1340: Module './test' does not refer to a type, but is used as a type here. Did you mean 'typeof import('./test')'?
+    

tests/baselines/reference/importUsedAsTypeWithErrors.js

@@ -0,0 +1,18 @@
+//// [tests/cases/compiler/importUsedAsTypeWithErrors.ts] ////
+
+//// [test.ts]
+export interface T {
+    value: string
+}
+
+//// [main.ts]
+export const a: import("./test") = null;
+
+
+//// [test.js]
+"use strict";
+exports.__esModule = true;
+//// [main.js]
+"use strict";
+exports.__esModule = true;
+exports.a = null;

tests/baselines/reference/importUsedAsTypeWithErrors.symbols

@@ -0,0 +1,12 @@
+=== tests/cases/compiler/test.ts ===
+export interface T {
+>T : Symbol(T, Decl(test.ts, 0, 0))
+
+    value: string
+>value : Symbol(T.value, Decl(test.ts, 0, 20))
+}
+
+=== tests/cases/compiler/main.ts ===
+export const a: import("./test") = null;
+>a : Symbol(a, Decl(main.ts, 0, 12))
+

tests/baselines/reference/importUsedAsTypeWithErrors.types

@@ -0,0 +1,13 @@
+=== tests/cases/compiler/test.ts ===
+export interface T {
+>T : T
+
+    value: string
+>value : string
+}
+
+=== tests/cases/compiler/main.ts ===
+export const a: import("./test") = null;
+>a : any
+>null : null
+

tests/cases/compiler/importUsedAsTypeWithErrors.ts

@@ -0,0 +1,7 @@
+// @filename: test.ts
+export interface T {
+    value: string
+}
+
+// @filename: main.ts
+export const a: import("./test") = null;