[clang] [NFC][analyzer] Refactor Environment to map Expr to SVal instead of Stmt to SVal (PR #193295)

[Balázs Benics via cfe-commits]

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@@ -886,7 +886,12 @@ static ProgramStateRef checkElementNonNil(CheckerContext &C,
     assert(ElemDecl->getInit() == nullptr);
     ElementLoc = State->getLValue(ElemDecl, LCtx);
   } else {
-    ElementLoc = State->getSVal(Element, LCtx).getAs<Loc>();
+    const Expr *Ex = dyn_cast<Expr>(Element);
+    if (Ex) {
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steakhal wrote:

I'd prefer an init-if stmt instead. Also keep trying the declarations DRY - in other words, if the type was already spelled on the line, just use `auto`.

https://github.com/llvm/llvm-project/pull/193295