Report every instance of TS1208 (global scripts not allowed under `isolatedModules`)

[wnayes]

Bug Report

When more than one global script file is present within a project using isolatedModules, only one error is raised for one of the problematic files.

File(1,1): error TS1208: 'File.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.

// No additional errors for File2.ts etc.

This behavior seems different from other errors that are logged when isolatedModules is enabled. It hides the extent to which a project is incompatible with isolatedModules.

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about isolatedModules

💻 Code

The behavior appears intentional in program.ts. It finds the first global script file and emits one diagnostic.

TypeScript/src/compiler/program.ts

Lines 3512 to 3517 in 7b76416

	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._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)));
	}

🙁 Actual behavior

One error of this kind is logged per compile.

🙂 Expected behavior

Log all of the violations, so that the extent of the problem can be assessed easily.

I changed the logic in program.ts locally to be a for loop that logged each problematic file, and I found this helpful for assessing the effort required to implement isolatedModules compatibility in an existing codebase.

[RyanCavanaugh]

I agree issuing one error per file seems like the better experience here