[NFC] Move DeclID from serialization/ASTBitCodes.h to AST/DeclID.h (#89873)

Previously, the DeclID is defined in serialization/ASTBitCodes.h under
clang::serialization namespace. However, actually the DeclID is not
purely used in serialization part. The DeclID is already widely used in
AST and all around the clang project via classes like `LazyPtrDecl` or
calling `ExternalASTSource::getExernalDecl()`. All such uses are via the
raw underlying type of `DeclID` as `uint32_t`. This is not pretty good.

This patch moves the DeclID class family to a new header `AST/DeclID.h`
so that the whole project can use the wrapped class `DeclID`,
`GlobalDeclID` and `LocalDeclID` instead of the raw underlying type.
This can improve the readability and the type safety.

1 files changed, 2 insertions, 2 deletions

diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 3610a08..361331d 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -1067,7 +1067,7 @@ public:
 
   std::vector<Decl *> takeTopLevelDecls() { return std::move(TopLevelDecls); }
 
-  std::vector<serialization::DeclID> takeTopLevelDeclIDs() {
+  std::vector<DeclID> takeTopLevelDeclIDs() {
     return std::move(TopLevelDeclIDs);
   }
 
@@ -1101,7 +1101,7 @@ public:
 private:
   unsigned Hash = 0;
   std::vector<Decl *> TopLevelDecls;
-  std::vector<serialization::DeclID> TopLevelDeclIDs;
+  std::vector<DeclID> TopLevelDeclIDs;
   llvm::SmallVector<ASTUnit::StandaloneDiagnostic, 4> PreambleDiags;
 };