out parameters checked in the right context; fixes p4lang#2175

frontends/p4/def_use.h

@@ -329,8 +329,7 @@ class Definitions : public IHasDbPrint {
     /// Set of program points that have written last to each location
     /// (conservative approximation).
     std::map<const BaseLocation*, const ProgramPoints*> definitions;
-    /// If true the current program point is actually unreachable and
-    /// it's definitions should not matter.
+    /// If true the current program point is actually unreachable.
     bool unreachable;
 
  public:
@@ -357,7 +356,6 @@ class Definitions : public IHasDbPrint {
     void dbprint(std::ostream& out) const {
         if (unreachable) {
             out << "  Unreachable";
-            return;
         }
         if (definitions.empty())
             out << "  Empty definitions";
@@ -414,6 +412,7 @@ class AllDefinitions : public IHasDbPrint {
  * @pre Must be executed after variable initializers have been removed.
  *
  */
+
 class ComputeWriteSet : public Inspector {
  protected:
     AllDefinitions*     allDefinitions;  /// Result computed by this pass.

frontends/p4/simplifyDefUse.cpp

@@ -191,10 +191,14 @@ class FindUninitialized : public Inspector {
         BUG_CHECK(findContext<IR::P4Program>() == nullptr, "Unexpected function");
         LOG3("FU Visiting function " << func->name << "[" << func->id << "]");
         LOG5(func);
+        auto callingContext = currentPoint;
         currentPoint = ProgramPoint(func);
         visit(func->body);
         bool checkReturn = !func->type->returnType->is<IR::Type_Void>();
-        checkOutParameters(func, func->type->parameters, getCurrentDefinitions(), checkReturn);
+        currentPoint = callingContext;  // We want the definitions after the function has completed,
+                                        // not after the last statement.
+        auto current = getCurrentDefinitions();
+        checkOutParameters(func, func->type->parameters, current, checkReturn);
         return false;
     }