fixes

Author: Frotty

de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/intermediatelang/optimizer/SideEffectAnalyzer.java

@@ -503,6 +503,11 @@ private boolean functionHasSideEffects(ImFunction func) {
                 cache.put(func, sideEffect);
                 return sideEffect;
             }
+            if (func.isExtern()) {
+                // Extern implementations are not represented in IM and may have runtime effects.
+                cache.put(func, true);
+                return true;
+            }
             if (!inProgress.add(func)) {
                 return true;
             }

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

@@ -9,8 +9,10 @@
 import de.peeeq.wurstscript.ast.WurstModel;
 import de.peeeq.wurstscript.intermediatelang.optimizer.FunctionSplitter;
 import de.peeeq.wurstscript.intermediatelang.optimizer.LocalMerger;
+import de.peeeq.wurstscript.intermediatelang.optimizer.SideEffectAnalyzer;
 import de.peeeq.wurstscript.jassIm.*;
 import de.peeeq.wurstscript.translation.imtranslation.ImTranslator;
+import de.peeeq.wurstscript.translation.imtranslation.FunctionFlagEnum;
 import de.peeeq.wurstscript.types.TypesHelper;
 import de.peeeq.wurstscript.utils.Utils;
 import io.vavr.collection.HashSet;
@@ -1156,6 +1158,39 @@ public void testFunctionSplitter() {
 
     }
 
+    @Test
+    public void externCallIsObservableSideEffectEvenWithEmptyBody() {
+        WurstModel model = Ast.WurstModel();
+        ImTranslator tr = new ImTranslator(model, false, new RunArgs());
+        ImProg prog = tr.getImProg();
+        Element trace = Ast.NoExpr();
+
+        ImFunction externFunc = JassIm.ImFunction(
+            trace,
+            "someExternCall",
+            JassIm.ImTypeVars(),
+            JassIm.ImVars(),
+            TypesHelper.imInt(),
+            JassIm.ImVars(),
+            JassIm.ImStmts(),
+            Collections.singletonList(FunctionFlagEnum.IS_EXTERN)
+        );
+        prog.getFunctions().add(externFunc);
+
+        ImFunctionCall externCall = JassIm.ImFunctionCall(
+            trace,
+            externFunc,
+            JassIm.ImTypeArguments(),
+            JassIm.ImExprs(),
+            false,
+            de.peeeq.wurstscript.translation.imtranslation.CallType.NORMAL
+        );
+
+        SideEffectAnalyzer analyzer = new SideEffectAnalyzer(prog);
+        assertTrue(analyzer.hasObservableSideEffects(externCall, f -> false),
+            "extern calls must be treated as observable side effects");
+    }
+
     @Test
     public void unaryMinus_minInt_notFolded() {
         testAssertOkLines(true,