[clang] [StaticAnalyzer] early return if sym is concrete on assuming (PR #115579)

[Ding Fei via cfe-commits]

danix800 wrote:

Yes these two are related.

Solver is the root cause, the checker crash is the effect. Either fix could cover the crash
but not enough without the other.

The solver is inherently incapable of solving some constraints, which would brings in
some overly constrainted states. We could try to improve the  solver's precision as much
as possible. In this case these impossible states would crash the checker.

The checker should protectively test against impossible states since they're inevitable.

https://github.com/llvm/llvm-project/pull/115579