Add ignoreDeadCode option

checker/src/main/java/org/checkerframework/checker/nullness/NullnessNoInitVisitor.java

@@ -290,9 +290,11 @@ protected boolean commonAssignmentCheck(
     /** Case 1: Check for null dereferencing. */
     @Override
     public Void visitMemberSelect(MemberSelectTree tree, Void p) {
-        // if (atypeFactory.isUnreachable(tree)) {
-        //     return super.visitMemberSelect(tree, p);
-        // }
+        if (checker.hasOption("notCheckDeadCode")) {
+            if (atypeFactory.isUnreachable(tree)) {
+                return super.visitMemberSelect(tree, p);
+            }
+        }
         Element e = TreeUtils.elementFromUse(tree);
         if (e.getKind() == ElementKind.CLASS) {
             if (atypeFactory.containsNullnessAnnotation(null, tree.getExpression())) {

docs/CHANGELOG.md

@@ -3,6 +3,9 @@ Version 3.40.0-eisop3 (November ??, 2023)
 
 **User-visible changes:**
 
+Add a new command-line argument `-AnotCheckDeadCode` disables the checker for code in dead expression.
+This option is not enabled by default.
+
 **Implementation details:**
 
 **Closed issues:**

framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java

@@ -5181,10 +5181,12 @@ protected TypeValidator createTypeValidator() {
      * @return true if checker should not test exprTree
      */
     protected final boolean shouldSkipUses(ExpressionTree exprTree) {
-        // System.out.printf("shouldSkipUses: %s: %s%n", exprTree.getClass(), exprTree);
-        // if (atypeFactory.isUnreachable(exprTree)) {
-        //     return true;
-        // }
+        if (checker.hasOption("notCheckDeadCode")) {
+            System.out.printf("shouldSkipUses: %s: %s%n", exprTree.getClass(), exprTree);
+            if (atypeFactory.isUnreachable(exprTree)) {
+                return true;
+            }
+        }
         Element elm = TreeUtils.elementFromTree(exprTree);
         return checker.shouldSkipUses(elm);
     }

framework/src/main/java/org/checkerframework/framework/source/SourceChecker.java

@@ -150,6 +150,9 @@
     // org.checkerframework.framework.source.SourceChecker.report
     "warns",
 
+    // Make checker ignore the expression in dead branch
+    "notCheckDeadCode",
+
     ///
     /// More sound (strict checking): enable errors that are disabled by default
     ///

framework/src/main/java/org/checkerframework/framework/type/GenericAnnotatedTypeFactory.java

@@ -458,7 +458,9 @@ public void setRoot(@Nullable CompilationUnitTree root) {
 
         super.setRoot(root);
         this.scannedClasses.clear();
-        // this.reachableNodes.clear();
+        if (checker.hasOption("notCheckDeadCode")) {
+            this.reachableNodes.clear();
+        }
         this.flowResult = null;
         this.regularExitStores.clear();
         this.exceptionalExitStores.clear();
@@ -1078,6 +1080,7 @@ public IPair<JavaExpression, String> getExpressionAndOffsetFromJavaExpressionStr
      * @param exprTree an expression tree
      * @return true if the {@code exprTree} is unreachable
      *
+     */
     public boolean isUnreachable(ExpressionTree exprTree) {
         if (!everUseFlow) {
             return false;
@@ -1096,7 +1099,6 @@ public boolean isUnreachable(ExpressionTree exprTree) {
         // None of the corresponding nodes is reachable, so this tree is dead.
         return true;
     }
-    */
 
     /**
      * Track the state of org.checkerframework.dataflow analysis scanning for each class tree in the
@@ -1120,7 +1122,7 @@ protected enum ScanState {
      * same name but represent different uses of the variable. So instead of storing Nodes, it
      * stores the result of {@code Node#getTree}.
      */
-    // private final Set<Tree> reachableNodes = new HashSet<>();
+    private final Set<Tree> reachableNodes = new HashSet<>();
 
     /**
      * The result of the flow analysis. Invariant:
@@ -1598,15 +1600,15 @@ protected void analyze(
             boolean isStatic,
             @Nullable Store capturedStore) {
         ControlFlowGraph cfg = CFCFGBuilder.build(root, ast, checker, this, processingEnv);
-        /*
-             cfg.getAllNodes(this::isIgnoredExceptionType)
-                     .forEach(
-                             node -> {
-                                 if (node.getTree() != null) {
-                                     reachableNodes.add(node.getTree());
-                                 }
-                             });
-        */
+        if (checker.hasOption("notCheckDeadCode")) {
+            cfg.getAllNodes(this::isIgnoredExceptionType)
+                    .forEach(
+                            node -> {
+                                if (node.getTree() != null) {
+                                    reachableNodes.add(node.getTree());
+                                }
+                            });
+        }
         if (isInitializationCode) {
             Store initStore = !isStatic ? initializationStore : initializationStaticStore;
             if (initStore != null) {