Add warning diagnostic for singleton Get yields

Author: Vorlias

src/Shared/diagnostics.ts

@@ -451,4 +451,11 @@ export const warnings = {
 		"Multi-dimensional arrays are not supported as properties",
 		suggestion("to turn off this warning, put @NonSerialized() in front of this property"),
 	),
+
+	singletonGetPossibleYield: warningWithContext((text: string) => {
+		return [
+			`This singleton Get call ${text} may yield the containing thread and cause an error at runtime!`,
+			suggestion("The call to get the singleton should be inside a function or method body"),
+		];
+	}),
 };

src/TSTransformer/classes/AirshipSymbolManager.ts

@@ -6,7 +6,10 @@ import { SINGLETON_FILE_IMPORT } from "TSTransformer/classes/TransformState";
 import { PROPERTY_SETTERS } from "TSTransformer/macros/propertyMacros";
 import { MacroList, PropertyCallMacro } from "TSTransformer/macros/types";
 import { skipUpwards } from "TSTransformer/util/traversal";
+import { findAncestorNode } from "TSTransformer/util/visitParentNodes";
 import ts from "typescript";
+import { DiagnosticService } from "./DiagnosticService";
+import { warnings } from "Shared/diagnostics";
 
 function getType(typeChecker: ts.TypeChecker, node: ts.Node) {
 	return typeChecker.getTypeAtLocation(skipUpwards(node));
@@ -39,11 +42,29 @@ const AIRSHIP_SERIALIZE_TYPES = {
 	AnimationCurve: "AnimationCurve",
 } as const;
 
+function isValidSingletonFetchContext(value: ts.Node) {
+	// Essentially anything that isn't ran during script setup
+	return (
+		ts.isMethodDeclaration(value) ||
+		ts.isFunctionDeclaration(value) ||
+		ts.isConstructorDeclaration(value) ||
+		ts.isFunctionExpression(value) ||
+		ts.isArrowFunction(value) ||
+		ts.isPropertyDeclaration(value)
+	);
+}
+
 export const AIRSHIP_SINGLETON_MACROS = {
 	Get: (state, node) => {
 		const importId = state.getOrAddFileImport(SINGLETON_FILE_IMPORT, "SingletonRegistry");
 		const Singletons_Resolve = luau.property(importId, "Resolve");
 
+		const ancestor = findAncestorNode(node, isValidSingletonFetchContext);
+
+		if (ancestor === undefined) {
+			DiagnosticService.addDiagnostic(warnings.singletonGetPossibleYield(node, node.getText()));
+		}
+
 		const functionType = state.typeChecker.getTypeAtLocation(node);
 		if (functionType !== undefined) {
 			return luau.call(Singletons_Resolve, [luau.string(state.typeChecker.typeToString(functionType))]);

src/TSTransformer/util/visitParentNodes.ts

@@ -0,0 +1,25 @@
+import ts from "typescript";
+
+function* visitParentNodes(node: ts.Node) {
+	let current = node.parent;
+
+	do {
+		yield current;
+		current = current.parent;
+	} while (current);
+}
+
+export function findAncestorNode<T extends ts.Node>(
+	node: ts.Node,
+	getNode: (value: ts.Node) => value is T,
+	breakAtNode?: (value: ts.Node) => boolean,
+) {
+	// if (getNode(node)) return node;
+
+	for (const parentNode of visitParentNodes(node)) {
+		if (breakAtNode?.(parentNode)) break;
+		if (getNode(parentNode)) return parentNode;
+	}
+
+	return undefined;
+}