Add support for raising if you set a tsconfig entry of target/module with the right setting in the root

src/compiler/commandLineParser.ts

@@ -2890,10 +2890,23 @@ namespace ts {
                         return;
                 }
             },
-            onSetUnknownOptionKeyValueInRoot(key: string, keyNode: PropertyName, _value: CompilerOptionsValue, _valueNode: Expression) {
+            onSetUnknownOptionKeyValueInRoot(key: string, keyNode: PropertyName, value: CompilerOptionsValue, _valueNode: Expression) {
                 if (key === "excludes") {
                     errors.push(createDiagnosticForNodeInSourceFile(sourceFile, keyNode, Diagnostics.Unknown_option_excludes_Did_you_mean_exclude));
                 }
+                if (key === "target") {
+                    const possibleValidEntries = arrayFrom(targetOptionDeclaration.type.keys());
+                    if (contains(possibleValidEntries, value)) {
+                        errors.push(createDiagnosticForNodeInSourceFile(sourceFile, keyNode, Diagnostics._0_should_be_set_inside_the_compilerOptions_object_of_the_tsconfig_json, "target"));
+                    }
+                }
+                if (key === "module") {
+                    const moduleOption = commandOptionsWithoutBuild.find(opt => opt.name === "module")!;
+                    const possibleValidEntries = arrayFrom((moduleOption.type as Map<string>).keys());
+                    if (contains(possibleValidEntries, value)) {
+                        errors.push(createDiagnosticForNodeInSourceFile(sourceFile, keyNode, Diagnostics._0_should_be_set_inside_the_compilerOptions_object_of_the_tsconfig_json, "module"));
+                    }
+                }
             }
         };
         const json = convertConfigFileToObject(sourceFile, errors, /*reportOptionsErrors*/ true, optionsIterator);

src/compiler/diagnosticMessages.json

@@ -4918,6 +4918,10 @@
         "category": "Message",
         "code": 6257
     },
+    "'{0}' should be set inside the 'compilerOptions' object of the tsconfig.json": {
+        "category": "Error",
+        "code": 6258
+    },
 
     "Projects to reference": {
         "category": "Message",

src/testRunner/unittests/config/convertCompilerOptionsFromJson.ts

@@ -663,6 +663,47 @@ namespace ts {
             });
         });
 
+
+        it("raises an error if you've set module to a correct string in the root", () => {
+            assertCompilerOptionsWithJsonText(`{
+                "module": "esnext",
+                "compilerOptions": {
+                    "target": "esnext"
+                }
+            }`, "tsconfig.json", {
+                compilerOptions: {
+                    target: ScriptTarget.ESNext
+                },
+                errors: [{
+                    ...Diagnostics._0_should_be_set_inside_the_compilerOptions_object_of_the_tsconfig_json,
+                    messageText: "'module' should be set inside the 'compilerOptions' object of the tsconfig.json.",
+                    file: undefined,
+                    start: 0,
+                    length: 0
+                }]
+            });
+        });
+
+        it("raises an error if you've set target to a correct string in the root", () => {
+            assertCompilerOptionsWithJsonText(`{
+                "target": "esnext",
+                "compilerOptions": {
+                    "module": "esnext"
+                }
+            }`, "tsconfig.json", {
+                compilerOptions: {
+                    module: ModuleKind.ESNext
+                },
+                errors: [{
+                    ...Diagnostics._0_should_be_set_inside_the_compilerOptions_object_of_the_tsconfig_json,
+                    messageText: "'target' should be set inside the 'compilerOptions' object of the tsconfig.json.",
+                    file: undefined,
+                    start: 0,
+                    length: 0
+                }]
+            });
+        });
+
         it("Don't crash when root expression is not objecty at all", () => {
             assertCompilerOptionsWithJsonText(`42`, "tsconfig.json", {
                 compilerOptions: {},