[clang] [NFC][analyzer] Spread use of 'Expr*' instead of 'Stmt*' (PR #188319)

[Balázs Benics via cfe-commits]

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@@ -297,17 +297,19 @@ void ExprEngine::processCallExit(ExplodedNode *CEBNode) {
   if (CE) {
     if (const ReturnStmt *RS = dyn_cast_or_null<ReturnStmt>(LastSt)) {
       const LocationContext *LCtx = CEBNode->getLocationContext();
+      // FIXME: This tries to look up the return statement in the environment,
+      // which is special cased to look up the subexpression RS->getRetValue()
+      // in environment. Instead of relying on this hack, pass
+      // RS->getRetValue() to getSVal() after checking it for nullness.
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steakhal wrote:

Okay. Changing the getSVal to only accept Exprs shouldn't be hard and would clarify things.  
I didn't understand what you mean by different overloads and that it queries the Environment.  
In my mind, `getSVal` can't to anything but to query from the Environment. So I didn't get what' was your confusion about.

https://github.com/llvm/llvm-project/pull/188319