[clang] [C++26] [Contracts] Support Parser, AST and AST Serialization (1/n) (PR #205739)

[Yihan Wang via cfe-commits]

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@@ -2131,6 +2190,11 @@ class FunctionDecl : public DeclaratorDecl,
   /// the DeclaratorDecl base class.
   DeclarationNameLoc DNLoc;
 
+  /// C++26 contract annotations (P2900R14). Each is a singly-linked list
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yronglin wrote:

```suggestion
  /// C++26 contract annotations. Each is a singly-linked list
```

https://github.com/llvm/llvm-project/pull/205739