[analyzer] Fix tagging of PostAllocatorCall (#142132)

By design the `Location` data member of a `CheckerContext` is always a
`ProgramPoint` which is tagged with the currently active checker (note
that all checker classes are subclasses of `ProgramPointTag`). This
ensures that exploded nodes created by the checker are by default tagged
by the checker object unless the checker specifies some other tag (e.g.
a note tag) when it calls the `addTransition`-like method that creates
the node.

This was followed by all the `CheckerManager::runCheckersForXXX`
methods, except for `runCheckerForNewAllocator`, where the
implementation constructed the `PostAllocatorCall` program point which
was used to create the `CheckerContext` without passing
`checkFn.Checker` as the tag of the program point.

This commit elimintates this inconsistency and adds an assertion to the
constructor of `CheckerContext` to ensure that this invariant will be
upheld even if we e.g. add a new program point kind.

I strongly suspect that this is a non-functional change because program
point tags are a vestigial feature in the codebase that barely affect
anything -- but e.g. their presence affects the infamous node
reclamation process, so I'm not marking this as NFC.

Author: NagyDonat

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

@@ -51,6 +51,8 @@ class CheckerContext {
       wasInlined(wasInlined) {
     assert(Pred->getState() &&
            "We should not call the checkers on an empty state.");
+    assert(loc.getTag() && "The ProgramPoint associated with CheckerContext "
+                           "must be tagged with the active checker.");
   }
 
   AnalysisManager &getAnalysisManager() {

clang/lib/StaticAnalyzer/Core/CheckerManager.cpp

@@ -585,8 +585,8 @@ namespace {
                     NodeBuilder &Bldr, ExplodedNode *Pred) {
       llvm::TimeTraceScope TimeScope(
           checkerScopeName("Allocator", checkFn.Checker));
-      ProgramPoint L =
-          PostAllocatorCall(Call.getOriginExpr(), Pred->getLocationContext());
+      ProgramPoint L = PostAllocatorCall(
+          Call.getOriginExpr(), Pred->getLocationContext(), checkFn.Checker);
       CheckerContext C(Bldr, Eng, Pred, L, WasInlined);
       checkFn(cast<CXXAllocatorCall>(*Call.cloneWithState(Pred->getState())),
               C);