[PATCH] D144626: [C++20] [Modules] Provide OriginalTrailingRequiresClause for serializer to perform ODR-Checking correctly

[Chuanqi Xu via Phabricator via cfe-commits]

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Close https://github.com/llvm/llvm-project/issues/60890.

For the following example:

  cpp
  export module a;
   
  export template<typename T>
  struct a {
  	friend void aa(a) requires(true) {
  	}
  };



  cpp
  export module b;
  
  import a;
  
  struct b {
  	a<int> m;
  };



  cpp
  export module c;
  
  import a;
  
  struct c {
  	void f() const {
  		aa(a<int>());
  	}
  };



  cpp
  import a;
  import b;
  import c;
  
  void d() {
  	aa(a<int>());
  }

The current clang will reject this incorrectly. The reason is that the require clause  will be replaced with the evaluated version (https://github.com/llvm/llvm-project/blob/efae3174f09560353fb0f3d528bcbffe060d5438/clang/lib/Sema/SemaConcept.cpp#L664-L665). In module 'b', the friend function is instantiated but not used so the require clause of the friend function is `(true)`. However, in module 'c', the friend function is used so the require clause is `true`. So deserializer classify these two function to two different functions instead of one. Then here is the bug report.

The proposed solution is to provide an original require clause which wouldn't change during the semantic analysis.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D144626

Files:
  clang/include/clang/AST/Decl.h
  clang/lib/AST/ASTContext.cpp
  clang/lib/AST/Decl.cpp
  clang/lib/Serialization/ASTReaderDecl.cpp
  clang/lib/Serialization/ASTWriterDecl.cpp
  clang/test/Modules/pr60890.cppm

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