[clang] [clang][analyzer] Fix argument invalidations in StreamChecker. (PR #79470)

[Alejandro Álvarez Ayllón via cfe-commits]

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@@ -763,6 +779,11 @@ void StreamChecker::evalFreadFwrite(const FnDescription *Desc,
     return;
   }
 
+  // At read, invalidate the buffer in any case of error or success,
+  // except if EOF was already present.
+  if (IsFread && (OldSS->ErrorState != ErrorFEof))
+    State = escapeArgs(State, C, Call, {0});
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alejandro-alvarez-sonarsource wrote:

It turns out I was comparing with our downstream copy of v17, where `UpdateBufferRegionForFread` is defined.
So it can be done for the case of arrays. I have double-checked with the original author and he agrees it can be upstreamed. Let me uplift the patch and then I will share it with you.

https://github.com/llvm/llvm-project/pull/79470