Retain preserved Lua class methods safely

Author: Frotty

de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/translation/lua/translation/RemoveGarbage.java

@@ -222,6 +222,11 @@ private static void visitFunction(ImFunction f, Used used) {
             return;
         }
         used.addFunction(f);
+        if (f.getParent() != null && f.getParent().getParent() instanceof ImClass owner) {
+            // A preserved static method has no receiver type to retain its owner. Keep the class
+            // because Lua emits class methods together with their class table.
+            visitClass(owner, used, false);
+        }
 
         visitType(f.getReturnType(), used);
         f.accept(new Element.DefaultVisitor() {

de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/validation/WurstValidator.java

@@ -87,8 +87,11 @@ public void validate(Collection<CompilationUnit> toCheck) {
             if (runtimeNameIndex != null) {
                 runtimeNameIndex.clearSyntheticMarkers();
             }
+            trveWrapperFuncs.clear();
+            wrapperCalls.clear();
             NamePreservation.clearSyntheticMarkers(prog);
             runtimeNameIndex = NamePreservation.indexGlobals(prog);
+            recomputeTrvePreservation();
 
             lightValidation(toCheck);
 
@@ -3265,19 +3268,11 @@ private void checkBannedFunctions(ExprFunctionCall e) {
                     return;
                 } else if (e.getArgs().get(1) instanceof ExprVarAccess) {
                     // Check if this is a two line hook... thanks Bribe
-                    ExprVarAccess varAccess = (ExprVarAccess) e.getArgs().get(1);
-                    @Nullable FunctionImplementation nearestFunc = e.attrNearestFuncDef();
-                    WStatements fbody = nearestFunc.getBody();
-                    if (e.getParent() instanceof StmtReturn && fbody.size() <= 4 && fbody.get(fbody.size() - 2).structuralEquals(e.getParent())) {
-                        WParameters params = nearestFunc.getParameters();
-                        if (params.size() == 4 && ((TypeExprSimple) params.get(0).getTyp()).getTypeName().equals("trigger")
-                            && ((TypeExprSimple) params.get(1).getTyp()).getTypeName().equals("string")
-                            && ((TypeExprSimple) params.get(2).getTyp()).getTypeName().equals("limitop")
-                            && ((TypeExprSimple) params.get(3).getTyp()).getTypeName().equals("real")) {
-                            trveWrapperFuncs.add(nearestFunc.getName());
-                            WLogger.info("found wrapper: " + nearestFunc.getName());
-                            return;
-                        }
+                    String wrapper = trveWrapperName(e);
+                    if (wrapper != null) {
+                        trveWrapperFuncs.add(wrapper);
+                        WLogger.info("found wrapper: " + wrapper);
+                        return;
                     }
                 }
             } else {
@@ -3318,6 +3313,66 @@ private void checkBannedFunctions(ExprFunctionCall e) {
         }
     }
 
+    private void recomputeTrvePreservation() {
+        prog.accept(new Element.DefaultVisitor() {
+            @Override
+            public void visit(ExprFunctionCall call) {
+                super.visit(call);
+                if (call.getFuncName().equals("TriggerRegisterVariableEvent") && call.getArgs().size() > 1) {
+                    if (call.getArgs().get(1) instanceof ExprStringVal varName) {
+                        preserveVariableName(varName.getValS());
+                    } else if (call.getArgs().get(1) instanceof ExprVarAccess) {
+                        String wrapper = trveWrapperName(call);
+                        if (wrapper != null) {
+                            trveWrapperFuncs.add(wrapper);
+                        }
+                    }
+                }
+            }
+
+        });
+
+        // Repeat the cheap call pass so calls which precede their wrapper declaration are covered.
+        prog.accept(new Element.DefaultVisitor() {
+            @Override
+            public void visit(ExprFunctionCall call) {
+                super.visit(call);
+                if (trveWrapperFuncs.contains(call.getFuncName())
+                    && call.getArgs().size() > 1
+                    && call.getArgs().get(1) instanceof ExprStringVal varName) {
+                    preserveVariableName(varName.getValS());
+                }
+            }
+        });
+    }
+
+    private @Nullable String trveWrapperName(ExprFunctionCall e) {
+        @Nullable FunctionImplementation nearestFunc = e.attrNearestFuncDef();
+        if (nearestFunc == null) {
+            return null;
+        }
+        WStatements fbody = nearestFunc.getBody();
+        if (!(e.getParent() instanceof StmtReturn)
+            || fbody.size() < 2
+            || fbody.size() > 4
+            || !fbody.get(fbody.size() - 2).structuralEquals(e.getParent())) {
+            return null;
+        }
+        WParameters params = nearestFunc.getParameters();
+        if (params.size() != 4
+            || !(params.get(0).getTyp() instanceof TypeExprSimple triggerType)
+            || !(params.get(1).getTyp() instanceof TypeExprSimple stringType)
+            || !(params.get(2).getTyp() instanceof TypeExprSimple limitopType)
+            || !(params.get(3).getTyp() instanceof TypeExprSimple realType)
+            || !triggerType.getTypeName().equals("trigger")
+            || !stringType.getTypeName().equals("string")
+            || !limitopType.getTypeName().equals("limitop")
+            || !realType.getTypeName().equals("real")) {
+            return null;
+        }
+        return nearestFunc.getName();
+    }
+
     private void preserveVariableName(String variableName) {
         runtimeNameIndex.preserve(variableName);
     }

de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/OptimizerTests.java

@@ -587,6 +587,22 @@ public void preserveNameAnnotationKeepsClassFunctionNameInLua() throws IOExcepti
             "Expected a preserved class function to keep its emitted name.\n" + output);
     }
 
+    @Test
+    public void preserveNameAnnotationKeepsStaticClassFunctionReachableInLua() throws IOException {
+        test().testLua(true).luaOnly(true).executeProg(false).lines(
+            "package test",
+            "    class ExternalApi",
+            "        @preserveName static function callback()",
+            "            skip",
+            "endpackage");
+
+        String output = Files.toString(
+            new File("./test-output/lua/OptimizerTests_preserveNameAnnotationKeepsStaticClassFunctionReachableInLua.lua"),
+            Charsets.UTF_8);
+        assertTrue(output.contains("function callback("),
+            "Expected a preserved static class function to keep its emitted name.\n" + output);
+    }
+
     @Test
     public void preservedClassFunctionReservesItsLuaNameBeforeClassVariables() throws IOException {
         test().testLua(true).luaOnly(true).executeProg(false).lines(