[analyzer][NFC] Turn NodeBuilderContext into a class (#84638)

From issue #73088. I changed `NodeBuilderContext` into a class.
Additionally, there were some other mentions of the former being a
struct which I also changed into a class. This is my first time working
with an issue so I will be open to hearing any advice or changes that
need to be done.

Author: sona-tau

clang/include/clang/StaticAnalyzer/Core/CheckerManager.h

@@ -49,7 +49,7 @@ class ExplodedNodeSet;
 class ExprEngine;
 struct EvalCallOptions;
 class MemRegion;
-struct NodeBuilderContext;
+class NodeBuilderContext;
 class ObjCMethodCall;
 class RegionAndSymbolInvalidationTraits;
 class SVal;

clang/include/clang/StaticAnalyzer/Core/PathSensitive/CoreEngine.h

@@ -59,7 +59,7 @@ class CoreEngine {
   friend class ExprEngine;
   friend class IndirectGotoNodeBuilder;
   friend class NodeBuilder;
-  friend struct NodeBuilderContext;
+  friend class NodeBuilderContext;
   friend class SwitchNodeBuilder;
 
 public:
@@ -193,12 +193,12 @@ class CoreEngine {
   DataTag::Factory &getDataTags() { return DataTags; }
 };
 
-// TODO: Turn into a class.
-struct NodeBuilderContext {
+class NodeBuilderContext {
   const CoreEngine &Eng;
   const CFGBlock *Block;
   const LocationContext *LC;
 
+public:
   NodeBuilderContext(const CoreEngine &E, const CFGBlock *B,
                      const LocationContext *L)
       : Eng(E), Block(B), LC(L) {
@@ -208,9 +208,15 @@ struct NodeBuilderContext {
   NodeBuilderContext(const CoreEngine &E, const CFGBlock *B, ExplodedNode *N)
       : NodeBuilderContext(E, B, N->getLocationContext()) {}
 
+  /// Return the CoreEngine associated with this builder.
+  const CoreEngine &getEngine() const { return Eng; }
+
   /// Return the CFGBlock associated with this builder.
   const CFGBlock *getBlock() const { return Block; }
 
+  /// Return the location context associated with this builder.
+  const LocationContext *getLocationContext() const { return LC; }
+
   /// Returns the number of times the current basic block has been
   /// visited on the exploded graph path.
   unsigned blockCount() const {

clang/include/clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h

@@ -85,7 +85,7 @@ class ExplodedNodeSet;
 class ExplodedNode;
 class IndirectGotoNodeBuilder;
 class MemRegion;
-struct NodeBuilderContext;
+class NodeBuilderContext;
 class NodeBuilderWithSinks;
 class ProgramState;
 class ProgramStateManager;

clang/lib/StaticAnalyzer/Core/CoreEngine.cpp

@@ -625,8 +625,8 @@ ExplodedNode* NodeBuilder::generateNodeImpl(const ProgramPoint &Loc,
                                             bool MarkAsSink) {
   HasGeneratedNodes = true;
   bool IsNew;
-  ExplodedNode *N = C.Eng.G.getNode(Loc, State, MarkAsSink, &IsNew);
-  N->addPredecessor(FromN, C.Eng.G);
+  ExplodedNode *N = C.getEngine().G.getNode(Loc, State, MarkAsSink, &IsNew);
+  N->addPredecessor(FromN, C.getEngine().G);
   Frontier.erase(FromN);
 
   if (!IsNew)
@@ -655,7 +655,7 @@ ExplodedNode *BranchNodeBuilder::generateNode(ProgramStateRef State,
   if (!isFeasible(branch))
     return nullptr;
 
-  ProgramPoint Loc = BlockEdge(C.Block, branch ? DstT:DstF,
+  ProgramPoint Loc = BlockEdge(C.getBlock(), branch ? DstT : DstF,
                                NodePred->getLocationContext());
   ExplodedNode *Succ = generateNodeImpl(Loc, State, NodePred);
   return Succ;