================================================================================
Namespace definitions
================================================================================

namespace std {

int x;

}  // namespace std

namespace A::B { }
namespace A::B::inline C { }
namespace A::B::inline C::D { }
inline namespace A { }

--------------------------------------------------------------------------------

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================================================================================
Namespace alias definitions
================================================================================

namespace A = B;
namespace C = ::D;
namespace fs = std::filesystem;
namespace bfs = ::boost::filesystem;
namespace literals = std::chono::literals;

--------------------------------------------------------------------------------

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================================================================================
Using declarations
================================================================================

using a;
using ::b;
using c::d;
using ::e::f::g;
using h = i::j;
using namespace std;
using enum Foo;

template <typename T>
using a = typename b<T>::c;

using foobar [[deprecated]] = int;
using foobar [[deprecated]] [[maybe_unused]] = int;

--------------------------------------------------------------------------------

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================================================================================
Reference declarations
================================================================================

int main() {
  T &x = y<T &>();
}

--------------------------------------------------------------------------------

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================================================================================
R-value reference declarations
================================================================================

int main(T &&);

int main(T &&t) {
  const U &&u = v;
}

--------------------------------------------------------------------------------

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================================================================================
Inline method definitions
================================================================================

struct S {
  int f;

  S() : f(0) {}

 private:
  int getF1() const { return f; }
  int getF2() const try { throw 1; } catch (...) { return f; }
};

--------------------------------------------------------------------------------

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================================================================================
Inline method definitions with overrides
================================================================================

struct B : A {
  int foo() override { return 2; }
  int pho() final { return 3; }
  int bar() const override { return 4; }
  int baz() const final { return 5; }
  int bag() const final override { return 6; }
  int bah() const override final;
  auto bai() const -> int override { return 7; }
  auto baj() const -> int override;
};

--------------------------------------------------------------------------------

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================================================================================
Virtual method declarations
================================================================================

class A {
  virtual ~Point();
  void b();
  virtual void foo() {}
  virtual void bar();
  inline virtual void foo() override;
  virtual inline void foo() final;
};

--------------------------------------------------------------------------------

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================================================================================
Constructor and destructor declarations
================================================================================

class C {
  void *data_;

 public:
  C();
  C(int, float);
  inline C();
  explicit inline C();
  [[deprecated]] C();
  template <typename T>
  C(T t);
  C() : NS::Base<C>() {}
  ~C();
};

--------------------------------------------------------------------------------

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      (declaration
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================================================================================
Classes with inheritance
================================================================================

class A : public B {};
class C : C::D, public E {};
class F : [[deprecated]] public G {};
class H : public virtual I {};
class J : virtual protected I {};
class K : virtual I {};
class L : protected I {};

--------------------------------------------------------------------------------

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================================================================================
Classes with final virt specifier
================================================================================

class A final : public B {
};

class C final {};

struct D final {};

--------------------------------------------------------------------------------

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================================================================================
Nested classes
================================================================================

class A {
 private:
  class B : private C, public D {
  };

  B e, f;
};

--------------------------------------------------------------------------------

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================================================================================
Friend declarations
================================================================================

struct C {
  friend class D;
  friend D;
  friend int f(C &);

  template <typename T>
  friend int g();
};

--------------------------------------------------------------------------------

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================================================================================
Default member initializers
================================================================================

struct A {
  bool a = 1;
  vector<int> b = {c, d, e};
  F g {h};
};

--------------------------------------------------------------------------------

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================================================================================
Function parameters with default values
================================================================================

int foo(bool x = 5) {}

--------------------------------------------------------------------------------

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================================================================================
Attributes
================================================================================

int f([[a::b(c), d]] int x) {}

[[gnu::always_inline]] [[gnu::hot]] [[gnu::const]] [[nodiscard]]
inline int g();

[[aaa]]
int f() { }

class [[gnu::visibility("default")]] A {};
struct [[gnu::visibility("default")]] A {};
union [[gnu::visibility("default")]] A {};

class [[gnu::visibility("default")]] [[deprecated]] A {};
class A final : [[deprecated]] public B {};

--------------------------------------------------------------------------------

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      (attribute
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================================================================================
Operator overload declarations
================================================================================

ostream &operator<<(ostream &, const A &a);
Foo operator "" _foo(const char* s);
std::string_view operator ""s_v(const char* s);
bool A::operator!=(const A &other) const;

bool A::operator ==(const A &other) const;

void * A::operator new(size_t s);

void * A::operator delete   [](void * p);

--------------------------------------------------------------------------------

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================================================================================
Template declarations
================================================================================

template <typename T>
void foo(T &t);

template <typename T, int u>
int bar(T &t) { return u; }

template <typename T>
class Foo {};

template <typename T>
Foo<T>::Foo(int mem) : mem_(mem) {}

template <typename T>
template <typename U>
void A<T>::foo(U&) {}

--------------------------------------------------------------------------------

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================================================================================
Template template declarations
================================================================================

template <template <typename> typename T>
void foo() {}

template <template <typename...> class>
void bar() {}

template <template <typename> typename...>
void baz() {}

--------------------------------------------------------------------------------

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        (template_parameter_list
          (type_parameter_declaration))
        (type_parameter_declaration
          (type_identifier))))
    (function_definition
      (primitive_type)
      (function_declarator
        (identifier)
        (parameter_list))
      (compound_statement)))
  (template_declaration
    (template_parameter_list
      (template_template_parameter_declaration
        (template_parameter_list
          (variadic_type_parameter_declaration))
        (type_parameter_declaration)))
    (function_definition
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        (identifier)
        (parameter_list))
      (compound_statement)))
  (template_declaration
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          (type_parameter_declaration))
        (variadic_type_parameter_declaration)))
    (function_definition
      (primitive_type)
      (function_declarator
        (identifier)
        (parameter_list))
      (compound_statement))))

================================================================================
Template specializations
================================================================================

template <>
void foo<T>(T &t);

template <>
struct foo::bar<T> {};

--------------------------------------------------------------------------------

(translation_unit
  (template_declaration
    (template_parameter_list)
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      (field_declaration_list))))

================================================================================
Template methods
================================================================================

class Person {
  Person() {
    this->speak<int>();
  }

  template <typename T>
  void speak() {}

  template <>
  void speak<bool>() {}
};

--------------------------------------------------------------------------------

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                  (primitive_type))))
            (parameter_list))
          (compound_statement))))))

================================================================================
Templates with optional type parameters
================================================================================

template <typename T = U::V<void>>
class X
{
};

template <typename = void>
class Y
{
};

--------------------------------------------------------------------------------

(translation_unit
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      (optional_type_parameter_declaration
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    (class_specifier
      name: (type_identifier)
      body: (field_declaration_list))))

================================================================================
Templates with optional anonymous parameters
================================================================================

template <class T, typename a::b<!c<T>{} && (d<T>{} || e<T>{})>::type = 0>
class X
{
};

--------------------------------------------------------------------------------

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                          value: (initializer_list)))))))
              name: (type_identifier))))
        default_value: (number_literal)))
    (class_specifier
      name: (type_identifier)
      body: (field_declaration_list))))

================================================================================
Declarations with braced initializer lists
================================================================================

A foo{1, 2};

--------------------------------------------------------------------------------

(translation_unit
  (declaration
    (type_identifier)
    (init_declarator
      (identifier)
      (initializer_list
        (number_literal)
        (number_literal)))))

================================================================================
Empty function bodies
================================================================================

int main() {}

--------------------------------------------------------------------------------

(translation_unit
  (function_definition
    (primitive_type)
    (function_declarator
      (identifier)
      (parameter_list))
    (compound_statement)))

================================================================================
Explicit template instantiations
================================================================================

template A<int, bool>::A(char *, size_t);

--------------------------------------------------------------------------------

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      (parameter_list
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        (parameter_declaration
          (primitive_type))))))

================================================================================
Structured binding declarations
================================================================================

auto [a] = B{};

int main() {
  auto &&[b, c] = std::make_tuple(c);
  const auto [x, y] {1, 2};

  for (const auto &[a, b] : c) {}
}

--------------------------------------------------------------------------------

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            (identifier))
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            (number_literal)
            (number_literal))))
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        (type_qualifier)
        type: (placeholder_type_specifier
          (auto))
        declarator: (reference_declarator
          (structured_binding_declarator
            (identifier)
            (identifier)))
        right: (identifier)
        body: (compound_statement)))))

================================================================================
Constexpr/constinit/consteval declarations
================================================================================

constexpr double pi = 3.14159;
consteval int answer();
constinit int life = answer();

--------------------------------------------------------------------------------

(translation_unit
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    (type_qualifier)
    (primitive_type)
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  (declaration
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  (declaration
    (type_qualifier)
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    (init_declarator
      (identifier)
      (call_expression
        (identifier)
        (argument_list)))))

================================================================================
Variadic templates
================================================================================

template <class T>
class TT {
  template <typename... Ts>
  void func1(Ts ... args) {
    func3(nullptr);
  }

  void func2(Ts &&... args) {}

  template <typename...>
  void func3() {}

  template <std::size_t...>
  void func4() {}
};

--------------------------------------------------------------------------------

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    (class_specifier
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              (variadic_declarator)))
          (function_definition
            (primitive_type)
            (function_declarator
              (identifier)
              (parameter_list))
            (compound_statement)))))))

================================================================================
Enums
================================================================================

enum Foo : char { };
enum Foo : Bar { };
enum Foo : unsigned int { };
enum {a, b};
enum Foo : Bar::Rab { };
enum Foo::Oof : Bar::Rab { };
enum class Foo;
enum struct Foo : char { };

class Foo {
  enum Bar {
    A, B
  };
};

--------------------------------------------------------------------------------

(translation_unit
  (enum_specifier
    (type_identifier)
    (primitive_type)
    (enumerator_list))
  (enum_specifier
    (type_identifier)
    (type_identifier)
    (enumerator_list))
  (enum_specifier
    (type_identifier)
    (sized_type_specifier
      (primitive_type))
    (enumerator_list))
  (enum_specifier
    (enumerator_list
      (enumerator
        (identifier))
      (enumerator
        (identifier))))
  (enum_specifier
    (type_identifier)
    (qualified_identifier
      (namespace_identifier)
      (type_identifier))
    (enumerator_list))
  (enum_specifier
    (qualified_identifier
      (namespace_identifier)
      (type_identifier))
    (qualified_identifier
      (namespace_identifier)
      (type_identifier))
    (enumerator_list))
  (enum_specifier
    (type_identifier))
  (enum_specifier
    (type_identifier)
    (primitive_type)
    (enumerator_list))
  (class_specifier
    (type_identifier)
    (field_declaration_list
      (field_declaration
        (enum_specifier
          (type_identifier)
          (enumerator_list
            (enumerator
              (identifier))
            (enumerator
              (identifier))))))))

================================================================================
static_assert declarations
================================================================================

class A { static_assert(true, "message"); };
void f() { static_assert(false); }
static_assert(std::is_constructible<A>::value);
static_assert(true, "string1" "string2");
static_assert(true, R"FOO(string)FOO");

--------------------------------------------------------------------------------

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  (class_specifier
    name: (type_identifier)
    body: (field_declaration_list
      (static_assert_declaration
        condition: (true)
        message: (string_literal
          (string_content)))))
  (function_definition
    type: (primitive_type)
    declarator: (function_declarator
      declarator: (identifier)
      parameters: (parameter_list))
    body: (compound_statement
      (static_assert_declaration
        condition: (false))))
  (static_assert_declaration
    condition: (qualified_identifier
      scope: (namespace_identifier)
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          name: (type_identifier)
          arguments: (template_argument_list
            (type_descriptor
              type: (type_identifier))))
        name: (identifier))))
  (static_assert_declaration
    condition: (true)
    message: (concatenated_string
      (string_literal
        (string_content))
      (string_literal
        (string_content))))
  (static_assert_declaration
    condition: (true)
    message: (raw_string_literal
      delimiter: (raw_string_delimiter)
      (raw_string_content)
      (raw_string_delimiter))))

================================================================================
Cast operator overload declarations
================================================================================

operator int() const;
explicit operator int*() const;
operator arr_t*();
operator B&();
operator auto() const;
virtual operator A() = 0;
A::B::operator C();
template <typename T>
operator T*();
[[nodiscard]] operator char *();

--------------------------------------------------------------------------------

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  (declaration
    (operator_cast
      (primitive_type)
      (abstract_function_declarator
        (parameter_list)
        (type_qualifier))))
  (declaration
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    (operator_cast
      (primitive_type)
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          (parameter_list)
          (type_qualifier)))))
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    (operator_cast
      (type_identifier)
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          (parameter_list)))))
  (declaration
    (operator_cast
      (type_identifier)
      (abstract_reference_declarator
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          (parameter_list)))))
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    (operator_cast
      (placeholder_type_specifier
        (auto))
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        (parameter_list)
        (type_qualifier))))
  (declaration
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    (operator_cast
      (type_identifier)
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        (parameter_list)))
    (number_literal))
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      (qualified_identifier
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        (operator_cast
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            (parameter_list))))))
  (template_declaration
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        (type_identifier)))
    (declaration
      (operator_cast
        (type_identifier)
        (abstract_pointer_declarator
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            (parameter_list))))))
  (declaration
    (attribute_declaration
      (attribute
        (identifier)))
    (operator_cast
      (primitive_type)
      (abstract_pointer_declarator
        (abstract_function_declarator
          (parameter_list))))))

================================================================================
Class scope cast operator overload declarations
================================================================================

class A {
  operator int() const {}
  explicit operator int*() const;
  operator arr_t*();
  operator B&();
  operator auto() const;
  virtual operator A() = 0;
  A::B::operator C();
  template <typename T>
  operator T*();
  [[nodiscard]] operator char *();
};

--------------------------------------------------------------------------------

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    (type_identifier)
    (field_declaration_list
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      (declaration
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      (declaration
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              (parameter_list)))))
      (declaration
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              (parameter_list)))))
      (declaration
        (operator_cast
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            (parameter_list)
            (type_qualifier))))
      (declaration
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        (operator_cast
          (type_identifier)
          (abstract_function_declarator
            (parameter_list)))
        (number_literal))
      (declaration
        (qualified_identifier
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          (qualified_identifier
            (namespace_identifier)
            (operator_cast
              (type_identifier)
              (abstract_function_declarator
                (parameter_list))))))
      (template_declaration
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          (type_parameter_declaration
            (type_identifier)))
        (declaration
          (operator_cast
            (type_identifier)
            (abstract_pointer_declarator
              (abstract_function_declarator
                (parameter_list))))))
      (declaration
        (attribute_declaration
          (attribute
            (identifier)))
        (operator_cast
          (primitive_type)
          (abstract_pointer_declarator
            (abstract_function_declarator
              (parameter_list))))))))

================================================================================
Function declarations
================================================================================

inline int g();
inline int h() { }

--------------------------------------------------------------------------------

(translation_unit
  (declaration
    (storage_class_specifier)
    type: (primitive_type)
    declarator: (function_declarator
      declarator: (identifier)
      parameters: (parameter_list)))
  (function_definition
    (storage_class_specifier)
    type: (primitive_type)
    declarator: (function_declarator
      declarator: (identifier)
      parameters: (parameter_list))
    body: (compound_statement)))

================================================================================
Variable storage classes
================================================================================

int a;
extern int b, c;
register int e;
static int f;
thread_local int c;

--------------------------------------------------------------------------------

(translation_unit
  (declaration
    (primitive_type)
    (identifier))
  (declaration
    (storage_class_specifier)
    (primitive_type)
    (identifier)
    (identifier))
  (declaration
    (storage_class_specifier)
    (primitive_type)
    (identifier))
  (declaration
    (storage_class_specifier)
    (primitive_type)
    (identifier))
  (declaration
    (storage_class_specifier)
    (primitive_type)
    (identifier)))

================================================================================
Ref-qualifiers
================================================================================

class C
{
  void f() &;
  void f() && noexcept;
  void f() & {}
  void f() & noexcept {}
};

void C::f() &;
void C::f() & noexcept;
void C::f() && {}
void C::f() & noexcept {}

--------------------------------------------------------------------------------

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        (primitive_type)
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          (field_identifier)
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        (primitive_type)
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          (field_identifier)
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        (compound_statement))
      (function_definition
        (primitive_type)
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  (function_definition
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    (function_declarator
      (qualified_identifier
        (namespace_identifier)
        (identifier))
      (parameter_list)
      (ref_qualifier)
      (noexcept))
    (compound_statement)))

================================================================================
Default comparison declarations
================================================================================

struct A {
    auto operator<=>(A const &) = default;
    friend auto operator<=>(A const &, A const &) = default;
};

--------------------------------------------------------------------------------

(translation_unit
  (struct_specifier
    (type_identifier)
    (field_declaration_list
      (function_definition
        (placeholder_type_specifier
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        (function_declarator
          (operator_name)
          (parameter_list
            (parameter_declaration
              (type_identifier)
              (type_qualifier)
              (abstract_reference_declarator))))
        (default_method_clause))
      (friend_declaration
        (declaration
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            (auto))
          (init_declarator
            (function_declarator
              (operator_name)
              (parameter_list
                (parameter_declaration
                  (type_identifier)
                  (type_qualifier)
                  (abstract_reference_declarator))
                (parameter_declaration
                  (type_identifier)
                  (type_qualifier)
                  (abstract_reference_declarator))))
            (identifier)))))))

================================================================================
Pointers in qualified identifiers and field expressions
================================================================================

class MyClass {
  public:
    int memberFunction(int value) {
        return value * 2;
    }
};

int main() {
    void (MyClass::*member_function_ptr)(int);
    MyClass obj;

    member_function_ptr = &MyClass::memberFunction;

    (obj.*member_function_ptr)(42); // 84

    this->Base::f();

    return 0;
}

--------------------------------------------------------------------------------

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    (type_identifier)
    (field_declaration_list
      (access_specifier)
      (function_definition
        (primitive_type)
        (function_declarator
          (field_identifier)
          (parameter_list
            (parameter_declaration
              (primitive_type)
              (identifier))))
        (compound_statement
          (return_statement
            (binary_expression
              (identifier)
              (number_literal)))))))
  (function_definition
    (primitive_type)
    (function_declarator
      (identifier)
      (parameter_list))
    (compound_statement
      (declaration
        (primitive_type)
        (function_declarator
          (parenthesized_declarator
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              (namespace_identifier)
              (pointer_type_declarator
                (type_identifier))))
          (parameter_list
            (parameter_declaration
              (primitive_type)))))
      (declaration
        (type_identifier)
        (identifier))
      (expression_statement
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          (identifier)
          (pointer_expression
            (qualified_identifier
              (namespace_identifier)
              (identifier)))))
      (expression_statement
        (call_expression
          (parenthesized_expression
            (field_expression
              (identifier)
              (field_identifier)))
          (argument_list
            (number_literal))))
      (comment)
      (expression_statement
        (call_expression
          (field_expression
            (this)
            (qualified_identifier
              (namespace_identifier)
              (field_identifier)))
          (argument_list)))
      (return_statement
        (number_literal)))))

================================================================================
Unnamed default parameter
================================================================================

class Foo {
    void foo(Bar& = defaultBar);
};

--------------------------------------------------------------------------------

(translation_unit
  (class_specifier
    (type_identifier)
    (field_declaration_list
      (field_declaration
        (primitive_type)
        (function_declarator
          (field_identifier)
          (parameter_list
            (optional_parameter_declaration
              (type_identifier)
              (abstract_reference_declarator)
              (identifier))))))))

================================================================================
Alignas specifier and alignof expression
================================================================================

struct sse_t {
    alignas(16) float sse_data[4];
};

struct data {
    char x;
    alignas(128) char cacheline[128]; // over-aligned array of char,
                                      // not array of over-aligned chars
};

int main(void) {
    printf("sizeof(data) = %zu (1 byte + 127 bytes padding + 128-byte array)\n",
           sizeof(struct data));

    printf("alignment of sse_t is %zu\n", alignof(struct sse_t));

    alignas(2048) struct data d; // this instance of data is aligned even stricter
    (void)d; // suppresses "maybe unused" warning
}

--------------------------------------------------------------------------------

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================================================================================
Attribute specifier after noexcept
================================================================================

inline constexpr MyEnum operator|(MyEnum bit0, MyEnum bit1) noexcept
    __attribute__((always_inline)) {}

--------------------------------------------------------------------------------

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