fix(15230): "Cannot compile namespaces" error with --isolatedModules and no namespaces

src/compiler/diagnosticMessages.json

@@ -659,7 +659,7 @@
         "category": "Error",
         "code": 1207
     },
-    "All files must be modules when the '--isolatedModules' flag is provided.": {
+    "'{0}' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.": {
         "category": "Error",
         "code": 1208
     },

src/compiler/program.ts

@@ -3110,7 +3110,8 @@ namespace ts {
                 const firstNonExternalModuleSourceFile = find(files, f => !isExternalModule(f) && !isSourceFileJS(f) && !f.isDeclarationFile && f.scriptKind !== ScriptKind.JSON);
                 if (firstNonExternalModuleSourceFile) {
                     const span = getErrorSpanForNode(firstNonExternalModuleSourceFile, firstNonExternalModuleSourceFile);
-                    programDiagnostics.add(createFileDiagnostic(firstNonExternalModuleSourceFile, span.start, span.length, Diagnostics.All_files_must_be_modules_when_the_isolatedModules_flag_is_provided));
+                    programDiagnostics.add(createFileDiagnostic(firstNonExternalModuleSourceFile, span.start, span.length,
+                        Diagnostics._0_cannot_be_compiled_under_isolatedModules_because_it_is_considered_a_global_script_file_Add_an_import_export_or_an_empty_export_statement_to_make_it_a_module, getBaseFileName(firstNonExternalModuleSourceFile.fileName)));
                 }
             }
             else if (firstNonAmbientExternalModuleSourceFile && languageVersion < ScriptTarget.ES2015 && options.module === ModuleKind.None) {

tests/baselines/reference/importHelpersInIsolatedModules.errors.txt

@@ -1,4 +1,4 @@
-tests/cases/compiler/script.ts(1,1): error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+tests/cases/compiler/script.ts(1,1): error TS1208: 'script.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
 
 
 ==== tests/cases/compiler/external.ts (0 errors) ====
@@ -16,7 +16,7 @@ tests/cases/compiler/script.ts(1,1): error TS1208: All files must be modules whe
 ==== tests/cases/compiler/script.ts (1 errors) ====
     class A { }
     ~~~~~
-!!! error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+!!! error TS1208: 'script.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
     class B extends A { }
 
     declare var dec: any;

tests/baselines/reference/isolatedModulesNoExternalModule.errors.txt

@@ -1,7 +1,7 @@
-tests/cases/compiler/file1.ts(1,1): error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+tests/cases/compiler/file1.ts(1,1): error TS1208: 'file1.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
 
 
 ==== tests/cases/compiler/file1.ts (1 errors) ====
     var x;
     ~~~
-!!! error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+!!! error TS1208: 'file1.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.

tests/baselines/reference/isolatedModulesOut.errors.txt

@@ -1,6 +1,6 @@
 error TS5053: Option 'out' cannot be specified with option 'isolatedModules'.
 tests/cases/compiler/file1.ts(1,1): error TS6131: Cannot compile modules using option 'out' unless the '--module' flag is 'amd' or 'system'.
-tests/cases/compiler/file2.ts(1,1): error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+tests/cases/compiler/file2.ts(1,1): error TS1208: 'file2.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
 
 
 !!! error TS5053: Option 'out' cannot be specified with option 'isolatedModules'.
@@ -11,4 +11,4 @@ tests/cases/compiler/file2.ts(1,1): error TS1208: All files must be modules when
 ==== tests/cases/compiler/file2.ts (1 errors) ====
     var y;
     ~~~
-!!! error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+!!! error TS1208: 'file2.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.

tests/baselines/reference/isolatedModulesPlainFile-AMD.errors.txt

@@ -1,9 +1,9 @@
-tests/cases/compiler/isolatedModulesPlainFile-AMD.ts(1,1): error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+tests/cases/compiler/isolatedModulesPlainFile-AMD.ts(1,1): error TS1208: 'isolatedModulesPlainFile-AMD.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
 
 
 ==== tests/cases/compiler/isolatedModulesPlainFile-AMD.ts (1 errors) ====
     declare function run(a: number): void;
     ~~~~~~~
-!!! error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+!!! error TS1208: 'isolatedModulesPlainFile-AMD.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
     run(1);
 

tests/baselines/reference/isolatedModulesPlainFile-CommonJS.errors.txt

@@ -1,9 +1,9 @@
-tests/cases/compiler/isolatedModulesPlainFile-CommonJS.ts(1,1): error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+tests/cases/compiler/isolatedModulesPlainFile-CommonJS.ts(1,1): error TS1208: 'isolatedModulesPlainFile-CommonJS.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
 
 
 ==== tests/cases/compiler/isolatedModulesPlainFile-CommonJS.ts (1 errors) ====
     declare function run(a: number): void;
     ~~~~~~~
-!!! error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+!!! error TS1208: 'isolatedModulesPlainFile-CommonJS.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
     run(1);
 

tests/baselines/reference/isolatedModulesPlainFile-ES6.errors.txt

@@ -1,9 +1,9 @@
-tests/cases/compiler/isolatedModulesPlainFile-ES6.ts(1,1): error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+tests/cases/compiler/isolatedModulesPlainFile-ES6.ts(1,1): error TS1208: 'isolatedModulesPlainFile-ES6.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
 
 
 ==== tests/cases/compiler/isolatedModulesPlainFile-ES6.ts (1 errors) ====
     declare function run(a: number): void;
     ~~~~~~~
-!!! error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+!!! error TS1208: 'isolatedModulesPlainFile-ES6.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
     run(1);
 

tests/baselines/reference/isolatedModulesPlainFile-System.errors.txt

@@ -1,9 +1,9 @@
-tests/cases/compiler/isolatedModulesPlainFile-System.ts(1,1): error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+tests/cases/compiler/isolatedModulesPlainFile-System.ts(1,1): error TS1208: 'isolatedModulesPlainFile-System.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
 
 
 ==== tests/cases/compiler/isolatedModulesPlainFile-System.ts (1 errors) ====
     declare function run(a: number): void;
     ~~~~~~~
-!!! error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+!!! error TS1208: 'isolatedModulesPlainFile-System.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
     run(1);
 

tests/baselines/reference/isolatedModulesPlainFile-UMD.errors.txt

@@ -1,9 +1,9 @@
-tests/cases/compiler/isolatedModulesPlainFile-UMD.ts(1,1): error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+tests/cases/compiler/isolatedModulesPlainFile-UMD.ts(1,1): error TS1208: 'isolatedModulesPlainFile-UMD.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
 
 
 ==== tests/cases/compiler/isolatedModulesPlainFile-UMD.ts (1 errors) ====
     declare function run(a: number): void;
     ~~~~~~~
-!!! error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+!!! error TS1208: 'isolatedModulesPlainFile-UMD.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
     run(1);
 

tests/baselines/reference/tscWatch/emit/emit-for-configured-projects/should-always-return-the-file-itself-if-'--isolatedModules'-is-specified.js

@@ -37,7 +37,7 @@ Output::
 [12:00:23 AM] Starting compilation in watch mode...
 
 
-a/b/globalFile3.ts:1:1 - error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+a/b/globalFile3.ts:1:1 - error TS1208: 'globalFile3.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
 
 1 interface GlobalFoo { age: number }
   ~~~~~~~~~
@@ -136,7 +136,7 @@ Output::
 [12:00:38 AM] File change detected. Starting incremental compilation...
 
 
-a/b/globalFile3.ts:1:1 - error TS1208: All files must be modules when the '--isolatedModules' flag is provided.
+a/b/globalFile3.ts:1:1 - error TS1208: 'globalFile3.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.
 
 1 interface GlobalFoo { age: number }
   ~~~~~~~~~