bug: C++20 modules export declarations are not parsed inside namespaces

[primitive0]

Did you check existing issues?

• I have read all the tree-sitter docs if it relates to using the parser
• I have searched the existing issues of tree-sitter-cpp

Tree-Sitter CLI Version, if relevant (output of tree-sitter --version)

No response

Describe the bug

Consider the following example:

export module cpp_module;

namespace X {

export int var_decl = 42;

export class ClassDecl {};

export void function_decl() {}

} // namespace X

According to the C++ standard, the export keyword can be used to export any declaration. Also, the code above can be successfully compiled using Clang 20.

However, tree-sitter-cpp does not parse these exported declarations correctly when they appear inside a namespace.

Steps To Reproduce/Bad Parse Tree

(translation_unit
 (module_declaration export module
  name: (module_name (identifier))
  ;)
 (namespace_definition namespace name: (namespace_identifier)
  body: 
   (declaration_list {
    (declaration type: (type_identifier)
     (ERROR (identifier))
     declarator: (init_declarator declarator: (identifier) = value: (number_literal))
     ;)
    (declaration type: (type_identifier)
     (ERROR (identifier))
     declarator: 
      (init_declarator declarator: (identifier)
       value: (initializer_list { }))
     ;)
    (function_definition type: (type_identifier)
     (ERROR (identifier))
     declarator: 
      (function_declarator declarator: (identifier)
       parameters: (parameter_list ( )))
     body: (compound_statement { }))
    }))
 (comment))

Expected Behavior/Parse Tree

(translation_unit
 (module_declaration export module
  name: (module_name (identifier))
  ;)
 (namespace_definition namespace name: (namespace_identifier)
  body: 
   (declaration_list {
    (export_declaration export
     (declaration type: (primitive_type)
      declarator: (init_declarator declarator: (identifier) = value: (number_literal))
      ;))
    (export_declaration export
     (class_specifier class name: (type_identifier)
      body: (field_declaration_list { }))
     ;)
    (export_declaration export
     (function_definition type: (primitive_type)
      declarator: 
       (function_declarator declarator: (identifier)
        parameters: (parameter_list ( )))
      body: (compound_statement { })))
    }))
 (comment))

Repro

export module cpp_module;

namespace X {

export int var_decl = 42;

export class ClassDecl {};

export void function_decl() {}

} // namespace X