TypeScriptToLua · Perryvw · Apr 2, 2022 · Apr 1, 2022 · Apr 1, 2022 · Apr 1, 2022
diff --git a/src/CompilerOptions.ts b/src/CompilerOptions.ts
@@ -21,7 +21,7 @@ export interface LuaPluginImport {
     [option: string]: any;
 }
 
-export type CompilerOptions = OmitIndexSignature<ts.CompilerOptions> & {
+export interface TypeScriptToLuaOptions {
     buildMode?: BuildMode;
     extension?: string;
     luaBundle?: string;
@@ -35,8 +35,13 @@ export type CompilerOptions = OmitIndexSignature<ts.CompilerOptions> & {
     plugins?: Array<ts.PluginImport | TransformerImport>;
     sourceMapTraceback?: boolean;
     tstlVerbose?: boolean;
-    [option: string]: any;
-};
+    lua51AllowTryCatchInAsyncAwait?: boolean;
+}
+
+export type CompilerOptions = OmitIndexSignature<ts.CompilerOptions> &
+    TypeScriptToLuaOptions & {
+        [option: string]: any;
+    };
 
 export enum LuaLibImportKind {
     None = "none",

diff --git a/src/cli/parse.ts b/src/cli/parse.ts
@@ -88,6 +88,11 @@ export const optionDeclarations: CommandLineOption[] = [
         description: "An array of paths that tstl should not resolve and keep as-is.",
         type: "array",
     },
+    {
+        name: "lua51AllowTryCatchInAsyncAwait",
+        description: "Always allow try/catch in async/await functions for Lua 5.1.",
+        type: "boolean",
+    },
 ];
 
 export function updateParsedConfigFile(parsedConfigFile: ts.ParsedCommandLine): ParsedCommandLine {

diff --git a/src/transformation/utils/diagnostics.ts b/src/transformation/utils/diagnostics.ts
@@ -1,5 +1,5 @@
 import * as ts from "typescript";
-import { LuaTarget } from "../../CompilerOptions";
+import { LuaTarget, TypeScriptToLuaOptions } from "../../CompilerOptions";
 import { createSerialDiagnosticFactory } from "../../utils";
 import { AnnotationKind } from "./annotations";
 
@@ -84,12 +84,23 @@ export const unsupportedRightShiftOperator = createErrorDiagnosticFactory(
     "Right shift operator is not supported for target Lua 5.3. Use `>>>` instead."
 );
 
+type NonUniversalTarget = Exclude<LuaTarget, LuaTarget.Universal>;
+
 const getLuaTargetName = (version: LuaTarget) => (version === LuaTarget.LuaJIT ? "LuaJIT" : `Lua ${version}`);
 export const unsupportedForTarget = createErrorDiagnosticFactory(
-    (functionality: string, version: Exclude<LuaTarget, LuaTarget.Universal>) =>
+    (functionality: string, version: NonUniversalTarget) =>
         `${functionality} is/are not supported for target ${getLuaTargetName(version)}.`
 );
 
+export const unsupportedForTargetButOverrideAvailable = createErrorDiagnosticFactory(
+    (functionality: string, version: NonUniversalTarget, optionName: keyof TypeScriptToLuaOptions) =>
+        `As a precaution, ${functionality} is/are not supported for target ${getLuaTargetName(
+            version
+        )} due to language features/limitations. ` +
+        `However "--${optionName}" can be used to bypass this precaution. ` +
+        "See https://typescripttolua.github.io/docs/configuration for more information."
+);
+
 export const unsupportedProperty = createErrorDiagnosticFactory(
     (parentName: string, property: string) => `${parentName}.${property} is unsupported.`
 );

diff --git a/src/transformation/visitors/errors.ts b/src/transformation/visitors/errors.ts
@@ -2,7 +2,7 @@ import * as ts from "typescript";
 import { LuaTarget } from "../..";
 import * as lua from "../../LuaAST";
 import { FunctionVisitor } from "../context";
-import { unsupportedForTarget } from "../utils/diagnostics";
+import { unsupportedForTarget, unsupportedForTargetButOverrideAvailable } from "../utils/diagnostics";
 import { createUnpackCall } from "../utils/lua-ast";
 import { ScopeType } from "../utils/scope";
 import { isInAsyncFunction, isInGeneratorFunction } from "../utils/typescript";
@@ -14,8 +14,19 @@ import { createReturnStatement } from "./return";
 export const transformTryStatement: FunctionVisitor<ts.TryStatement> = (statement, context) => {
     const [tryBlock, tryScope] = transformScopeBlock(context, statement.tryBlock, ScopeType.Try);
 
-    if (context.options.luaTarget === LuaTarget.Lua51 && isInAsyncFunction(statement)) {
-        context.diagnostics.push(unsupportedForTarget(statement, "try/catch inside async functions", LuaTarget.Lua51));
+    if (
+        context.options.luaTarget === LuaTarget.Lua51 &&
+        isInAsyncFunction(statement) &&
+        !context.options.lua51AllowTryCatchInAsyncAwait
+    ) {
+        context.diagnostics.push(
+            unsupportedForTargetButOverrideAvailable(
+                statement,
+                "try/catch inside async functions",
+                LuaTarget.Lua51,
+                "lua51AllowTryCatchInAsyncAwait"
+            )
+        );
         return tryBlock.statements;
     }
 

diff --git a/test/unit/builtins/async-await.spec.ts b/test/unit/builtins/async-await.spec.ts
@@ -1,6 +1,7 @@
 import { ModuleKind, ScriptTarget } from "typescript";
 import { LuaTarget } from "../../../src";
-import { awaitMustBeInAsyncFunction, unsupportedForTarget } from "../../../src/transformation/utils/diagnostics";
+import { unsupportedForTargetButOverrideAvailable } from "../../../src/transformation/utils/diagnostics";
+import { awaitMustBeInAsyncFunction } from "../../../src/transformation/utils/diagnostics";
 import * as util from "../../util";
 
 const promiseTestLib = `
@@ -540,7 +541,8 @@ describe("try/catch in async function", () => {
         // Cannot execute LuaJIT with test runner
         {
             ...util.expectEachVersionExceptJit(builder => builder.expectToEqual({ result: 4 })),
-            [LuaTarget.Lua51]: builder => builder.expectToHaveDiagnostics([unsupportedForTarget.code]),
+            [LuaTarget.Lua51]: builder =>
+                builder.expectToHaveDiagnostics([unsupportedForTargetButOverrideAvailable.code]),
         }
     );
 
@@ -563,7 +565,8 @@ describe("try/catch in async function", () => {
             ...util.expectEachVersionExceptJit(builder =>
                 builder.expectToEqual({ reason: "an error occurred in the async function: test error" })
             ),
-            [LuaTarget.Lua51]: builder => builder.expectToHaveDiagnostics([unsupportedForTarget.code]),
+            [LuaTarget.Lua51]: builder =>
+                builder.expectToHaveDiagnostics([unsupportedForTargetButOverrideAvailable.code]),
         }
     );
 
@@ -590,7 +593,8 @@ describe("try/catch in async function", () => {
             ...util.expectEachVersionExceptJit(builder =>
                 builder.expectToEqual({ reason: "an error occurred in the async function: test error" })
             ),
-            [LuaTarget.Lua51]: builder => builder.expectToHaveDiagnostics([unsupportedForTarget.code]),
+            [LuaTarget.Lua51]: builder =>
+                builder.expectToHaveDiagnostics([unsupportedForTargetButOverrideAvailable.code]),
         }
     );
 });