now a warning + implicit fix

Author: Frotty

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

@@ -1643,14 +1643,14 @@ private void checkUninitializedVars(FunctionLike f) {
             && !f.getSource().getFile().endsWith("blizzard.j")
             && !f.getSource().getFile().endsWith("war3map.j")) {
             new DataflowAnomalyAnalysis(Utils.isJassCode(f)).execute(f);
-            checkJassImplicitNullLocalsReadWithoutExplicitWrite(f);
         }
+        checkJassImplicitNullLocalsReadWithoutExplicitWrite(f);
     }
 
     /**
      * JASS compatibility shim: we currently synthesize "= null" for uninitialized non-primitive
      * locals to avoid invalid emitted JASS. Still report likely user bugs early when such a local
-     * is read but never explicitly assigned in the input.
+     * is read before its first explicit assignment in the input.
      */
     private void checkJassImplicitNullLocalsReadWithoutExplicitWrite(FunctionLike f) {
         if (!Utils.isJassCode(f)) {
@@ -1671,27 +1671,84 @@ public void visit(LocalVarDef localVarDef) {
             return;
         }
 
-        Set<LocalVarDef> explicitWrites = new HashSet<>();
+        Set<LocalVarDef> implicitNullLocalSet = new HashSet<>(implicitNullLocals);
+        Map<LocalVarDef, StmtSet> firstExplicitWrite = new HashMap<>();
         f.accept(new Element.DefaultVisitor() {
             @Override
             public void visit(StmtSet stmtSet) {
                 super.visit(stmtSet);
                 NameLink link = stmtSet.getUpdatedExpr().attrNameLink();
                 if (link != null && link.getDef() instanceof LocalVarDef) {
-                    explicitWrites.add((LocalVarDef) link.getDef());
+                    LocalVarDef local = (LocalVarDef) link.getDef();
+                    if (!implicitNullLocalSet.contains(local)) {
+                        return;
+                    }
+                    StmtSet previous = firstExplicitWrite.get(local);
+                    if (previous == null
+                        || stmtSet.attrSource().getLeftPos() < previous.attrSource().getLeftPos()) {
+                        firstExplicitWrite.put(local, stmtSet);
+                    }
+                }
+            }
+        });
+
+        Set<LocalVarDef> readBeforeExplicitWrite = new HashSet<>();
+        f.accept(new Element.DefaultVisitor() {
+            @Override
+            public void visit(ExprVarAccess varAccess) {
+                super.visit(varAccess);
+                NameLink link = varAccess.attrNameLink();
+                if (link == null || !(link.getDef() instanceof LocalVarDef)) {
+                    return;
+                }
+                LocalVarDef local = (LocalVarDef) link.getDef();
+                if (!implicitNullLocalSet.contains(local)) {
+                    return;
+                }
+                if (isWriteTarget(varAccess)) {
+                    return;
+                }
+                StmtSet firstWrite = firstExplicitWrite.get(local);
+                if (firstWrite == null) {
+                    readBeforeExplicitWrite.add(local);
+                    return;
+                }
+                StmtSet enclosingSet = nearestEnclosingStmtSet(varAccess);
+                if (enclosingSet == firstWrite) {
+                    readBeforeExplicitWrite.add(local);
+                    return;
+                }
+                if (varAccess.attrSource().getLeftPos() < firstWrite.attrSource().getLeftPos()) {
+                    readBeforeExplicitWrite.add(local);
                 }
             }
         });
 
         for (LocalVarDef local : implicitNullLocals) {
-            if (explicitWrites.contains(local)) {
-                continue;
+            if (readBeforeExplicitWrite.contains(local)) {
+                local.addWarning("Variable " + local.getName()
+                    + " is read before explicit initialization in input JASS; defaulting to null.");
             }
-            if (f.attrReadVariables().contains(local)) {
-                local.addError("Variable " + local.getName()
-                    + " is read before explicit initialization in input JASS.");
+        }
+    }
+
+    private boolean isWriteTarget(ExprVarAccess varAccess) {
+        if (!(varAccess.getParent() instanceof StmtSet)) {
+            return false;
+        }
+        StmtSet set = (StmtSet) varAccess.getParent();
+        return set.getUpdatedExpr() == varAccess;
+    }
+
+    private @Nullable StmtSet nearestEnclosingStmtSet(Element e) {
+        Element current = e.getParent();
+        while (current != null) {
+            if (current instanceof StmtSet) {
+                return (StmtSet) current;
             }
+            current = current.getParent();
         }
+        return null;
     }
 
     private boolean isImplicitNullInit(LocalVarDef localVarDef) {

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

@@ -54,7 +54,7 @@ public void jassLocalHandleDefaultsToNull() {
 
     @Test
     public void jassLocalHandleReadWithoutExplicitInitReportsEarly() {
-        testAssertErrorsLinesWithStdLib(false, "read before explicit initialization in input JASS",
+        testAssertWarningsLinesWithStdLib(false, "read before explicit initialization in input JASS",
             "function tiw takes nothing returns nothing",
             "local location uiw",
             "call RemoveLocation(uiw)",
@@ -66,4 +66,38 @@ public void jassLocalHandleReadWithoutExplicitInitReportsEarly() {
         );
     }
 
+    @Test
+    public void war3mapJassLocalHandleReadWithoutExplicitInitReportsEarly() {
+        test()
+            .withStdLib()
+            .setStopOnFirstError(false)
+            .executeProg(false)
+            .expectWarning("read before explicit initialization in input JASS")
+            .compilationUnits(
+                compilationUnit("war3map.j",
+                    "function showUnitTextAlliesWithZ takes nothing returns nothing",
+                    "local location p2",
+                    "call RemoveLocation(p2)",
+                    "endfunction"
+                )
+            );
+    }
+
+    @Test
+    public void jassLocalHandleReadBeforeLaterWriteStillWarns() {
+        testAssertWarningsLinesWithStdLib(false, "read before explicit initialization in input JASS",
+            "function tiw takes nothing returns nothing",
+            "local location uiw",
+            "call RemoveLocation(uiw)",
+            "set uiw = GetRectCenter(GetPlayableMapRect())",
+            "call RemoveLocation(uiw)",
+            "set uiw = null",
+            "endfunction",
+            "package B",
+            "    init",
+            "        tiw()",
+            "endpackage"
+        );
+    }
+
 }