[clang] [clang][nullability] Don't discard expression state before end of full-expression. (PR #82611)

[Yitzhak Mandelbaum via cfe-commits]

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@@ -248,12 +251,12 @@ class JoinedStateBuilder {
       // initialize the state of each basic block differently.
       return {AC.Analysis.typeErasedInitialElement(), AC.InitEnv.fork()};
     if (All.size() == 1)
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ymand wrote:

guard on ExprBehavior as well, like `if (All.size() == 1 && ExprBehavior == DiscardExprState)`? Then, could you drop the FIXME and "if desired"?

https://github.com/llvm/llvm-project/pull/82611