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2 changes: 1 addition & 1 deletion src/LuaPrinter.ts
Original file line number Diff line number Diff line change
Expand Up @@ -328,7 +328,7 @@ export class LuaPrinter {

statementNodes.push(node);

if (lua.isReturnStatement(statement)) break;
if (lua.isReturnStatement(statement) || lua.isBreakStatement(statement)) break;
}

return statementNodes.length > 0 ? [...intersperse<SourceChunk>(statementNodes, "\n"), "\n"] : [];
Expand Down
93 changes: 93 additions & 0 deletions test/unit/printer/deadCodeAfterBreak.spec.ts
Original file line number Diff line number Diff line change
@@ -0,0 +1,93 @@
import * as tstl from "../../../src";
import * as util from "../../util";

// In Lua 5.0, 5.1, and LuaJIT, break must be the last statement in a block.
// Any code after break is a syntax error (e.g. `while true do break; local b = 8 end`
// fails with "'end' expected near 'local'"). Lua 5.2+ relaxed this restriction.
// TSTL should strip dead code after break on all targets to avoid these errors.

function expectNoDeadCode(builder: util.TestBuilder) {
const lua = builder.getMainLuaCodeChunk();
expect(lua).not.toContain("local b = 8");
}

const affectedVersions: Record<tstl.LuaTarget, ((builder: util.TestBuilder) => void) | boolean> = {
[tstl.LuaTarget.Universal]: false,
[tstl.LuaTarget.Lua50]: builder => builder.tap(expectNoDeadCode).expectToMatchJsResult(),
[tstl.LuaTarget.Lua51]: builder => builder.tap(expectNoDeadCode).expectToMatchJsResult(),
[tstl.LuaTarget.Lua52]: false,
[tstl.LuaTarget.Lua53]: false,
[tstl.LuaTarget.Lua54]: false,
[tstl.LuaTarget.Lua55]: false,
[tstl.LuaTarget.LuaJIT]: builder => builder.tap(expectNoDeadCode),
[tstl.LuaTarget.Luau]: false,
};

util.testEachVersion(
"for dead code after break",
() => util.testFunction`
let result = 0;
for (let i = 0; i < 10; i++) { result = i; break; const b = 8; }
return result;
`,
affectedVersions
);

util.testEachVersion(
"for..in dead code after break",
() => util.testFunction`
let result = "";
for (let a in {"a": 5, "b": 8}) { result = a; break; const b = 8; }
return result;
`,
affectedVersions
);

util.testEachVersion(
"for..of dead code after break",
() => util.testFunction`
let result = 0;
for (let a of [1,2,4]) { result = a; break; const b = 8; }
return result;
`,
affectedVersions
);

util.testEachVersion(
"while dead code after break",
() => util.testFunction`
let result = "done";
while (true) { break; const b = 8; }
return result;
`,
affectedVersions
);

util.testEachVersion(
"switch dead code after break",
() => util.testFunction`
let result = "none";
switch ("abc" as string) {
case "def":
result = "def";
break;
let abc = 4;
case "abc":
result = "abc";
break;
let def = 6;
}
return result;
`,
affectedVersions
);

util.testEachVersion(
"do-while dead code after break",
() => util.testFunction`
let result = "done";
do { break; const b = 8; } while (true);
return result;
`,
affectedVersions
);
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