[clang] [clang][Sema] Fix Issue: #166957 - type inconsistency for constrained auto variables(Fixes #166957) (PR #167100)

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KaushalMorankar wrote:

The bug was in the internal type consistency between getTypeSourceInfo()->getType() and getType(). I added compilation tests that serve as regression tests to ensure these patterns continue to compile correctly. While these tests don't directly verify the AST
consistency, they cover various scenarios where constrained auto is used, and I manually verified the fix by running AST dump on the test cases to confirm the AutoType objects have correct dependency flags and are consistent.

https://github.com/llvm/llvm-project/pull/167100