[clang] [analyzer] Check the correct first and last elements in cstring.UninitializedRead (PR #95408)

[Donát Nagy via cfe-commits]

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@@ -461,7 +446,7 @@ ProgramStateRef CStringChecker::checkInit(CheckerContext &C,
   if (!ER)
     return State;
 
-  const TypedValueRegion *Orig = getOriginRegion(ER);
+  const auto *Orig = ER->getSuperRegion()->getAs<TypedValueRegion>();
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NagyDonat wrote:

Nitpick: also change the name "`Orig`".

https://github.com/llvm/llvm-project/pull/95408