[clang] [clang][analyzer] Model more getline/getdelim pre and postconditions (PR #83027)

[Alejandro Álvarez Ayllón via cfe-commits]

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@@ -1196,6 +1342,11 @@ void StreamChecker::evalGetdelim(const FnDescription *Desc,
       E.isStreamEof() ? ErrorFEof : ErrorFEof | ErrorFError;
   StateFailed = E.setStreamState(
       StateFailed, StreamState::getOpened(Desc, NewES, !NewES.isFEof()));
+  // On failure, the content of the buffer is undefined.
+  if (auto NewLinePtr = getPointeeDefVal(Call.getArgSVal(0), State)) {
+    StateFailed = StateFailed->bindLoc(*NewLinePtr, UndefinedVal(),
+                                       C.getLocationContext());
+  }
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alejandro-alvarez-sonarsource wrote:

Yes, in [`test_getline_no_return_check()`](https://github.com/llvm/llvm-project/pull/83027/files#diff-243f1fa5dbb855f53ee0b05c1da2383352ec55ee9375a214c477df00592f1737R183)

https://github.com/llvm/llvm-project/pull/83027