Don’t emit diagnostic accessing UMD globals from modules when flag is set

Author: andrewbranch

src/compiler/checker.ts

@@ -1632,10 +1632,10 @@ namespace ts {
                 }
 
                 // If we're in an external module, we can't reference value symbols created from UMD export declarations
-                if (result && isInExternalModule && (meaning & SymbolFlags.Value) === SymbolFlags.Value && !(originalLocation!.flags & NodeFlags.JSDoc)) {
+                if (!compilerOptions.allowUmdGlobalAccess && result && isInExternalModule && (meaning & SymbolFlags.Value) === SymbolFlags.Value && !(originalLocation!.flags & NodeFlags.JSDoc)) {
                     const merged = getMergedSymbol(result);
                     if (length(merged.declarations) && every(merged.declarations, d => isNamespaceExportDeclaration(d) || isSourceFile(d) && !!d.symbol.globalExports)) {
-                        error(errorLocation!, Diagnostics._0_refers_to_a_UMD_global_but_the_current_file_is_a_module_Consider_adding_an_import_instead, unescapeLeadingUnderscores(name)); // TODO: GH#18217
+                        error(errorLocation!, Diagnostics._0_refers_to_a_UMD_global_but_the_current_file_is_a_module_Consider_adding_an_import_instead, unescapeLeadingUnderscores(name));
                     }
                 }
             }