[clang] [clang-tools-extra] [Clang][AST] Introduce `ExplicitInstantiationDecl` to preserve source info and fix diagnostic locations (PR #191658)

[via cfe-commits]

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@@ -3405,6 +3405,122 @@ getReplacedTemplateParameter(Decl *D, unsigned Index);
 /// If we have an implicit instantiation, adjust 'D' to refer to template.
 const Decl &adjustDeclToTemplate(const Decl &D);
 
+/// Represents an explicit instantiation of a template entity in source code.
+///
+/// This node records source location information for an explicit instantiation
+/// statement. It does not participate in name lookup (inherits from Decl, not
+/// NamedDecl), and does not affect code generation. The underlying
+/// specialization decl (FunctionDecl, VarDecl, CXXRecordDecl, etc.) continues
+/// to handle all semantic and codegen responsibilities.
+///
+/// \code
+///   template void ns::foo<int>(int);        // function template
+///   extern template struct ns::S<int>;      // class template (extern)
+///   template int ns::bar<int>;              // variable template
+///   template void ns::S<int>::method(int);  // member function
+/// \endcode
+class ExplicitInstantiationDecl : public Decl {
+  /// The underlying specialization being explicitly instantiated.
+  NamedDecl *Specialization = nullptr;
+
+  /// The source range of the entire explicit instantiation statement.
+  SourceRange Range;
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16bit-ykiko wrote:

Fixed.

https://github.com/llvm/llvm-project/pull/191658