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Merged
Frotty merged 2 commits into from
Sep 4, 2026
Merged

Deduplicate Lua callback adapters #1290

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1c8e627
Deduplicate Lua callback adapters
Frotty Sep 3, 2026
6ef1338
Preserve renamed Lua callback targets
Frotty Sep 3, 2026
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37 changes: 1 addition & 36 deletions ...cript/src/main/java/de/peeeq/wurstscript/translation/lua/translation/ExprTranslation.java
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Original file line number Diff line number Diff line change
Expand Up @@ -53,42 +53,7 @@ public static LuaExpr translate(ImDealloc e, LuaTranslator tr) {
}

public static LuaExpr translate(ImFuncRef e, LuaTranslator tr) {
// return LuaAst.LuaExprFuncRef(tr.luaFunc.getFor(e.getFunc()));
// alternative: use xpcall to get stacktraces (did not work)
boolean returnsValue = !(e.getFunc().getReturnType() instanceof ImVoid);
LuaVariable dots = LuaAst.LuaVariable("...", LuaAst.LuaNoExpr());
LuaStatements callbackBody = LuaAst.LuaStatements();
if (returnsValue) {
LuaVariable tempRes = LuaAst.LuaVariable("tempRes", LuaAst.LuaExprNull());
callbackBody.add(tempRes);
callbackBody.add(LuaAst.LuaExprFunctionCallByName("xpcall",
LuaAst.LuaExprlist(
LuaAst.LuaExprFunctionAbstraction(
LuaAst.LuaParams(dots.copy()),
LuaAst.LuaStatements(
LuaAst.LuaAssignment(LuaAst.LuaExprVarAccess(tempRes),
LuaAst.LuaExprFunctionCall(tr.luaFunc.getFor(e.getFunc()), LuaAst.LuaExprlist(LuaAst.LuaExprVarAccess(dots.copy())))))
),
LuaAst.LuaLiteral("function(err) if err == \"" + WURST_ABORT_THREAD_SENTINEL + "\" then return end BJDebugMsg(\"lua callback error: \" .. tostring(err)) xpcall(function() " + callErrorFunc(tr, "tostring(err)", "in lua callback error handler") + " end, function(err2) if err2 == \"" + WURST_ABORT_THREAD_SENTINEL + "\" then return end BJDebugMsg(\"error reporting error: \" .. tostring(err2)) BJDebugMsg(\"while reporting: \" .. tostring(err)) end) end"),
LuaAst.LuaExprVarAccess(dots.copy())
)
));
callbackBody.add(LuaAst.LuaReturn(LuaAst.LuaExprVarAccess(tempRes)));
} else {
callbackBody.add(LuaAst.LuaExprFunctionCallByName("xpcall",
LuaAst.LuaExprlist(
LuaAst.LuaExprFunctionAbstraction(
LuaAst.LuaParams(dots.copy()),
LuaAst.LuaStatements(
LuaAst.LuaExprFunctionCall(tr.luaFunc.getFor(e.getFunc()), LuaAst.LuaExprlist(LuaAst.LuaExprVarAccess(dots.copy())))
)
),
LuaAst.LuaLiteral("function(err) if err == \"" + WURST_ABORT_THREAD_SENTINEL + "\" then return end BJDebugMsg(\"lua callback error: \" .. tostring(err)) xpcall(function() " + callErrorFunc(tr, "tostring(err)", "in lua callback error handler") + " end, function(err2) if err2 == \"" + WURST_ABORT_THREAD_SENTINEL + "\" then return end BJDebugMsg(\"error reporting error: \" .. tostring(err2)) BJDebugMsg(\"while reporting: \" .. tostring(err)) end) end"),
LuaAst.LuaExprVarAccess(dots.copy())
)
));
}
return LuaAst.LuaExprFunctionAbstraction(LuaAst.LuaParams(dots), callbackBody);
return LuaAst.LuaExprFuncRef(tr.callbackAdapterFor(e.getFunc()));
}

static String callErrorFunc(LuaTranslator tr, String msg) {
Expand Down
64 changes: 64 additions & 0 deletions ...tscript/src/main/java/de/peeeq/wurstscript/translation/lua/translation/LuaTranslator.java
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Original file line number Diff line number Diff line change
Expand Up @@ -137,6 +137,8 @@ private ImProg getProg() {

List<ExprTranslation.TupleFunc> tupleEqualsFuncs = new ArrayList<>();
List<ExprTranslation.TupleFunc> tupleCopyFuncs = new ArrayList<>();
private final Map<ImFunction, LuaFunction> callbackAdapters = new IdentityHashMap<>();
private LuaFunction callbackErrorHandler;

// Array-default infrastructure (metatables/helper functions) shared across
// every array of a given entry type, instead of allocated per array
Expand Down Expand Up @@ -385,6 +387,68 @@ public LuaCompilationUnit translate() {
return luaModel;
}

/**
* Function references need an xpcall boundary, but the boundary is a property of the referenced
* function rather than of each expression which names it. Emit one reusable adapter per target
* so evaluating a function reference performs no closure allocation.
*/
LuaFunction callbackAdapterFor(ImFunction target) {
LuaFunction existing = callbackAdapters.get(target);
if (existing != null) {
return existing;
}

LuaFunction targetLua = luaFunc.getFor(target);
LuaVariable dots = LuaAst.LuaVariable("...", LuaAst.LuaNoExpr());
LuaFunction adapter = LuaAst.LuaFunction(
uniqueName("__wurst_callback_" + targetLua.getName()),
LuaAst.LuaParams(dots), LuaAst.LuaStatements());
callbackAdapters.put(target, adapter);

LuaFunction errorHandler = callbackErrorHandler();
LuaExprFunctionCallByName xpcall = LuaAst.LuaExprFunctionCallByName("xpcall",
LuaAst.LuaExprlist(
LuaAst.LuaExprFuncRef(targetLua),
LuaAst.LuaExprFuncRef(errorHandler),
LuaAst.LuaExprVarAccess(dots.copy())));
if (target.getReturnType() instanceof ImVoid) {
adapter.getBody().add(xpcall);
} else {
// Keep exactly the first callback result. Returning select(2, xpcall(...)) directly
// could leak additional Lua return values into a surrounding argument list.
LuaVariable ignored = LuaAst.LuaVariable("_", LuaAst.LuaNoExpr());
LuaVariable result = LuaAst.LuaVariable("result", LuaAst.LuaNoExpr());
adapter.getBody().add(ignored);
adapter.getBody().add(result);
adapter.getBody().add(LuaAst.LuaAssignment(
LuaAst.LuaLiteral("_, result"), xpcall));
adapter.getBody().add(LuaAst.LuaReturn(LuaAst.LuaExprVarAccess(result)));
}
luaModel.add(adapter);
return adapter;
}

private LuaFunction callbackErrorHandler() {
if (callbackErrorHandler != null) {
return callbackErrorHandler;
}
LuaVariable err = LuaAst.LuaVariable("err", LuaAst.LuaNoExpr());
callbackErrorHandler = LuaAst.LuaFunction(uniqueName("__wurst_callback_error"),
LuaAst.LuaParams(err), LuaAst.LuaStatements());
callbackErrorHandler.getBody().add(LuaAst.LuaLiteral(
"if err == \"" + ExprTranslation.WURST_ABORT_THREAD_SENTINEL + "\" then return end"));
callbackErrorHandler.getBody().add(LuaAst.LuaLiteral(
"BJDebugMsg(\"lua callback error: \" .. tostring(err))"));
callbackErrorHandler.getBody().add(LuaAst.LuaLiteral(
"xpcall(function() " + ExprTranslation.callErrorFunc(this, "tostring(err)",
"in lua callback error handler")
+ " end, function(err2) if err2 == \"" + ExprTranslation.WURST_ABORT_THREAD_SENTINEL
+ "\" then return end BJDebugMsg(\"error reporting error: \" .. tostring(err2))"
+ " BJDebugMsg(\"while reporting: \" .. tostring(err)) end)"));
luaModel.add(callbackErrorHandler);
return callbackErrorHandler;
}

/**
* Rejects calls/references to functions that an earlier optimizer pass
* detached from the IM program. Without this invariant the Lua printer
Expand Down
76 changes: 75 additions & 1 deletion de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/LuaTranslationTests.java
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Original file line number Diff line number Diff line change
Expand Up @@ -128,6 +128,15 @@ private List<String> uniqueMatches(String output, String regex, int group) {
return result;
}

private int countMatches(String output, String regex) {
Matcher matcher = Pattern.compile(regex).matcher(output);
int result = 0;
while (matcher.find()) {
result++;
}
return result;
}

private String singleMatch(String output, String regex, int group) {
Matcher matcher = Pattern.compile(regex).matcher(output);
assertTrue("Expected pattern to occur: " + regex, matcher.find());
Expand Down Expand Up @@ -173,6 +182,11 @@ private String compileLuaWithRunArgs(String testName, boolean withStdLib, String

private String compileLuaWithCUs(String testName, boolean withStdLib, List<CU> extraCUs, String... lines) {
RunArgs runArgs = new RunArgs().with("-lua", "-inline", "-localOptimizations", "-stacktraces");
return compileLuaWithCUs(testName, withStdLib, extraCUs, runArgs, lines);
}

private String compileLuaWithCUs(String testName, boolean withStdLib, List<CU> extraCUs,
RunArgs runArgs, String... lines) {
WurstGui gui = new WurstGuiCliImpl();
WurstCompilerJassImpl compiler = new WurstCompilerJassImpl(null, gui, null, runArgs);
List<CU> inputs = new ArrayList<>();
Expand Down Expand Up @@ -2475,12 +2489,72 @@ public void luaFunctionRefWrapperForwardsVarargs() throws IOException {
" ForForce(f, () -> skip)"
);
String compiled = Files.toString(new File("test-output/lua/LuaTranslationTests_luaFunctionRefWrapperForwardsVarargs.lua"), Charsets.UTF_8);
assertTrue(compiled.contains("xpcall(function (...)"));
assertContainsRegex(compiled, "function\\s+__wurst_callback_[A-Za-z0-9_]+\\(\\.\\.\\.\\)");
assertFalse(compiled.contains("xpcall(function (...)"));
assertContainsRegex(compiled,
"xpcall\\([A-Za-z0-9_]+, __wurst_callback_error[A-Za-z0-9_]*, \\.\\.\\.\\)");
assertTrue(compiled.contains(", ...)"));
assertFalse(compiled.contains("local temp = ..."));
assertFalse(compiled.contains("ForForce(f, function (...) \n\t\t\tlocal tempRes"));
}

@Test
public void luaFunctionRefsReuseOneAdapterAndPreserveSingleReturn() {
String compiled = compileLuaWithCUs(
"LuaTranslationTests_luaFunctionRefsReuseOneAdapterAndPreserveSingleReturn",
false,
Collections.emptyList(),
new RunArgs().with("-lua", "-inline", "-localOptimizations"),
"type boolexpr extends handle",
"package Test",
"@extern native Condition(code callback) returns boolexpr",
"function predicate() returns boolean",
" return true",
"init",
" let first = Condition(function predicate)",
" let second = Condition(function predicate)"
);

List<String> adapters = uniqueMatches(compiled,
"function\\s+(__wurst_callback_predicate[A-Za-z0-9_]*)\\(\\.\\.\\.\\)", 1);
assertEquals("one adapter must serve every reference to the same function:\n" + compiled,
1, adapters.size());
String adapter = adapters.get(0);
assertEquals("both Condition calls must reference the cached adapter", 2,
countMatches(compiled, "Condition\\(" + Pattern.quote(adapter) + "\\)"));
String adapterBody = getFunctionBody(compiled, adapter);
assertTrue(adapterBody.contains("_, result = xpcall(predicate,"));
assertTrue(adapterBody.contains("return result"));
assertFalse("callback sites must not allocate anonymous wrappers", compiled.contains("Condition(function ("));
}

@Test
public void luaFunctionRefAdapterTracksLateClassFunctionRename() {
String compiled = compileLuaWithCUs(
"LuaTranslationTests_luaFunctionRefAdapterTracksLateClassFunctionRename",
false,
Collections.emptyList(),
new RunArgs().with("-lua"),
"package Test",
"@extern native consume(code callback)",
"@extern native CallbackOwner_staticCallback()",
"class CallbackOwner",
" function start()",
" consume(function staticCallback)",
" private static function staticCallback()",
" consume(function staticCallback)",
"init",
" CallbackOwner_staticCallback()",
" new CallbackOwner().start()"
);

String callbackName = singleMatch(compiled,
"function\\s+(CallbackOwner_[A-Za-z0-9_]*staticCallback[A-Za-z0-9_]*)\\(\\)", 1);
assertTrue("adapter must track the class callback's final name:\n" + compiled,
compiled.contains("xpcall(" + callbackName + ","));
assertFalse(compiled.contains("xpcall(staticCallback,"));
}

@Test
public void luaFunctionRefStacktraceHandlerUsesWurstStackPosition() throws IOException {
CU errorHandling = new CU("ErrorHandling.wurst", String.join("\n",
Expand Down
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