[clang] [clang][dataflow] Process terminator condition within `transferCFGBlock()`. (PR #77750)

[Yitzhak Mandelbaum via cfe-commits]

================
@@ -489,6 +482,31 @@ transferCFGBlock(const CFGBlock &Block, AnalysisContext &AC,
     }
     AC.Log.recordState(State);
   }
+
+  // If we have a terminator, evaluate its condition.
+  // This `Expr` may not appear as a `CFGElement` anywhere else, and it's
+  // important that we evaluate it here (rather than while processing the
+  // terminator) so that we put the corresponding value in the right
+  // environment.
+  if (const Expr *TerminatorCond =
+          dyn_cast_or_null<Expr>(Block.getTerminatorCondition())) {
+    if (State.Env.getValue(*TerminatorCond) == nullptr)
+      // FIXME: This only runs the builtin transfer, not the analysis-specific
+      // transfer. Fixing this isn't trivial, as the analysis-specific transfer
+      // takes a `CFGElement` as input, but some expressions only show up as a
+      // terminator condition, but not as a `CFGElement`. The condition of an if
----------------
ymand wrote:

CFGElement is cheap to construct. Can you just wrap the expression and pass it on?

https://github.com/llvm/llvm-project/pull/77750