fix(to_cpp1): improve recognition of dependent types and deducible pa…

…rameters

regression-tests/pure2-bugfix-for-deducible-parameters.cpp2

@@ -0,0 +1,33 @@
+// Dependent, non-deducible parameters
+// are wrapped like non-dependent parameters.
+init: <T> (out x: std::integral_constant<i32, T::value>) = { x = (); }
+init: <T> (out x: std::integral_constant<i32, T::value>, _: T) = { x = (); }
+id: <T> (x: std::integral_constant<i32, T::value>) -> forward _ = x;
+id: <T> (x: std::integral_constant<i32, T::value>, y: T) = { assert(x& == y&); }
+
+main: () = {
+  zero: type == std::integral_constant<i32, 0>;
+
+  z: zero;
+  init<zero>(out z);
+  assert(id<zero>(z)& == z&);
+
+  // Deducible parameters.
+  _ = :v = 0;
+  _ = :<T> (x: std::vector<T>) = {}(:std::vector<i32> = ());
+  _ = :<T> (x: std::vector<std::vector<T>>) = {}(:std::vector<std::vector<i32>> = ());
+  // _ = :<T, U> (x: std::pair<T, typename U::value_type>, y: U) = {}(:std::pair = (0, 0), z); // Blocked on #727.
+  _ = :<T, U> (x: std::array<T, U::value>, y: U) = {}(:std::array<i32, 0> = (), z);
+  init(out z, z);
+  id(z, z);
+
+  // Test that these are emitted unwrapped in case they are deducible.
+  (copy f := :<T> (x: std::vector<std::type_identity_t<T>>) = {})
+    static_assert(!std::is_invocable_v<decltype(f), std::vector<i32>>, "`T` is non-deducible.");
+  (copy f := :<T> (x: std::vector<std::vector<T>>) = {})
+    static_assert(std::is_invocable_v<decltype(f), std::vector<std::vector<i32>>>, "`T` is deducible.");
+}
+
+v: <T> type = {
+  operator=: (out this, x: T) = { }
+}

regression-tests/pure2-bugfix-for-dependent-types-recursion.cpp2

@@ -0,0 +1,6 @@
+main: () = {
+  a: type == b;
+  b: type == a;
+  _ = a::t;
+  _ = b::t;
+}

regression-tests/pure2-bugfix-for-dependent-types.cpp2

@@ -0,0 +1,91 @@
+identity: <T> type == T;
+
+f: <T, V: T::value_type> (x: T::value_type) -> T::value_type = {
+  assert(x is T::value_type);
+  y: T::value_type;
+  y = x;
+  z: type == T::value_type;
+  return (:T::value_type = x);
+
+  // Dependent *template-id*s.
+  _ = :identity<T>::value_type = ();      // First identifier.
+  _ = :std::optional<T>::value_type = (); // Non-first identifier.
+  _ = :std::array<i32, T::value>::value_type = ();
+  _ = :std::array<i32, T::value + T::value>::value_type = ();
+
+  // Emitted `template`.
+  ptr: type  == * T; // Also test lookup through type aliases.
+  nptr: type == * i32;
+  _ = :std::pointer_traits<ptr>::rebind<ptr> = ();   // Type-only context.
+  _ = :std::pointer_traits<nptr>::rebind<nptr> = (); // Non-dependent.
+  _ = :std::pointer_traits<nptr>::rebind<ptr> = ();  // Dependent on the nested template.
+  _ = :std::pointer_traits<ptr>::rebind<nptr> = ();  // Dependent on the outer template.
+  // _ = :identity<typename std::pointer_traits<ptr>::rebind<ptr>> = (); // Non type-only context. Blocked on #727.
+
+  // Aliases.
+  w: type == T;
+  _ = :w::value_type = x;
+  v: type == w;
+  _ = :v::value_type = x;
+  a: type == T::type;
+  _ = :a::value_type = x;
+
+  {
+    // Test that there's no prefixed `typename` to....
+    _ = std::integral_constant<i32, T::value>(); // `T::value`.
+    _ = :std::type_identity_t<T> = ();           // `std::type_identity_t<T>`.
+
+    // Test that non-dependent names aren't emitted with `typename`.
+    a: type == std::integral_constant<i32, 0>;
+    b: type == a;
+    c: type == b;
+    _ = :b::value_type = x;
+    _ = :c::value_type = x;
+  }
+}
+
+t: @struct <T: type> type = {
+  u: @struct type = {
+    x: T::value_type = ();
+    this: T::type    = ();
+  }
+  x: T::value_type = 0;
+}
+
+main: () = {
+  zero: type == std::integral_constant<i32, 0>;
+  _ = f<zero, 0>(0);
+
+  // clang-format off
+  _ = : ::t<zero> = (); // clang-format on
+
+  // Emitted `template` (noop, taken care of by the UFCS macro).
+  _ = :(f) = { _ = f.operator()<i32>(); }(:<T> () = {});
+
+  // Nesting is not relevant to lookup.
+  _ = :<T> () = { _ = :T::value_type = (); };
+  _ = :() = { _ = :<T> () = { _ = :T::value_type = (); }; };
+  _ = :() = { _ = :() = { _ = :<T> () = { _ = :T::value_type = (); }; }; };
+  _ = :() = { _ = :() = { _ = :() = { _ = :<T> () = { _ = :T::value_type = (); }; }; }; };
+  _ = :() = { _ = :() = { _ = :<T> () = { _ = :() = { _ = :T::value_type = (); }; }; }; };
+  _ = :() = { _ = :<T> () = { _ = :() = { _ = :() = { _ = :T::value_type = (); }; }; }; };
+  _ = :<T> () = { _ = :() = { _ = :() = { _ = :() = { _ = :T::value_type = (); }; }; }; };
+  _ = :<T> () = { _ = :() = { _ = :() = { _ = :(x: T::value_type) = {}; }; }; };
+  _ = :<T> () = { _ = :() = { _ = :(x: T::value_type) = { _ = :() = {}; }; }; };
+  _ = :<T> () = { _ = :(x: T::value_type) = { _ = :() = { _ = :() = {}; }; }; };
+  _ = :<T> (x: T::value_type) = { _ = :() = { _ = :() = { _ = :() = {}; }; }; };
+
+  // Lookup.
+  {
+    alias: type == std::integral_constant<i32, 0>;
+    _ = :alias::value_type = 0; // Non-dependent.
+  }
+  _ = :<T> (_: T) = {
+    alias: type == std::integral_constant<T, 0>;
+    _ = :alias::value_type = 0; // Dependent.
+    {
+      alias: type == std::integral_constant<i32, 0>;
+      _ = :alias::value_type = 0; // Non-dependent.
+    }
+  }(0);
+}

regression-tests/test-results/gcc-13/pure2-bugfix-for-dependent-types-recursion.cpp.output

@@ -0,0 +1,13 @@
+pure2-bugfix-for-dependent-types-recursion.cpp: In function ‘int main()’:
+pure2-bugfix-for-dependent-types-recursion.cpp:19:13: error: ‘b’ does not name a type
+   19 |   using a = b;
+      |             ^
+pure2-bugfix-for-dependent-types-recursion.cpp:20:13: error: ‘a’ does not name a type
+   20 |   using b = a;
+      |             ^
+pure2-bugfix-for-dependent-types-recursion.cpp:21:21: error: ‘a’ has not been declared
+   21 |   static_cast<void>(a::t);
+      |                     ^
+pure2-bugfix-for-dependent-types-recursion.cpp:22:21: error: ‘b’ has not been declared
+   22 |   static_cast<void>(b::t);
+      |                     ^

regression-tests/test-results/pure2-bugfix-for-deducible-parameters.cpp

@@ -0,0 +1,87 @@
+
+#define CPP2_IMPORT_STD          Yes
+
+//=== Cpp2 type declarations ====================================================
+
+
+#include "cpp2util.h"
+
+
+#line 31 "pure2-bugfix-for-deducible-parameters.cpp2"
+template<typename T> class v;
+
+
+//=== Cpp2 type definitions and function declarations ===========================
+
+// Dependent, non-deducible parameters
+// are wrapped like non-dependent parameters.
+#line 3 "pure2-bugfix-for-deducible-parameters.cpp2"
+template<typename T> auto init(cpp2::out<std::integral_constant<cpp2::i32,T::value>> x) -> void;
+template<typename T> auto init(cpp2::out<std::integral_constant<cpp2::i32,T::value>> x, [[maybe_unused]] T const& param2) -> void;
+template<typename T> [[nodiscard]] auto id(cpp2::in<std::integral_constant<cpp2::i32,T::value>> x) -> auto&&;
+template<typename T> auto id(cpp2::in<std::integral_constant<cpp2::i32,T::value>> x, T const& y) -> void;
+
+auto main() -> int;
+
+
+#line 31 "pure2-bugfix-for-deducible-parameters.cpp2"
+template<typename T> class v {
+  public: explicit v(T const& x);
+#line 32 "pure2-bugfix-for-deducible-parameters.cpp2"
+  public: auto operator=(T const& x) -> v& ;
+
+  public: v(v const&) = delete; /* No 'that' constructor, suppress copy */
+  public: auto operator=(v const&) -> void = delete;
+#line 33 "pure2-bugfix-for-deducible-parameters.cpp2"
+};
+
+
+//=== Cpp2 function definitions =================================================
+
+
+#line 3 "pure2-bugfix-for-deducible-parameters.cpp2"
+template<typename T> auto init(cpp2::out<std::integral_constant<cpp2::i32,T::value>> x) -> void{x.construct(); }
+template<typename T> auto init(cpp2::out<std::integral_constant<cpp2::i32,T::value>> x, [[maybe_unused]] T const& param2) -> void{x.construct(); }
+template<typename T> [[nodiscard]] auto id(cpp2::in<std::integral_constant<cpp2::i32,T::value>> x) -> auto&& { return x;  }
+template<typename T> auto id(cpp2::in<std::integral_constant<cpp2::i32,T::value>> x, T const& y) -> void{cpp2::Default.expects(&x == &y, ""); }
+
+auto main() -> int{
+  using zero = std::integral_constant<cpp2::i32,0>;
+
+  cpp2::deferred_init<zero> z; 
+  init<zero>(cpp2::out(&z));
+  cpp2::Default.expects(&id<zero>(z.value()) == &z.value(), "");
+
+  // Deducible parameters.
+  static_cast<void>(v{0});
+  static_cast<void>([]<typename T>(std::vector<T> const& x) -> void{}(std::vector<cpp2::i32>{}));
+  static_cast<void>([]<typename T>(std::vector<std::vector<T>> const& x) -> void{}(std::vector<std::vector<cpp2::i32>>{}));
+  // _ = :<T, U> (x: std::pair<T, typename U::value_type>, y: U) = {}(:std::pair = (0, 0), z); // Blocked on #727.
+  static_cast<void>([]<typename T, typename U>(std::array<T,U::value> const& x, U const& y) -> void{}(std::array<cpp2::i32,0>{}, z.value()));
+  init(cpp2::out(&z.value()), z.value());
+  id(z.value(), std::move(z.value()));
+{
+auto f = []<typename T>(std::vector<std::type_identity_t<T>> const& x) -> void{};
+
+  // Test that these are emitted unwrapped in case they are deducible.
+
+#line 26 "pure2-bugfix-for-deducible-parameters.cpp2"
+    static_assert(!(std::is_invocable_v<decltype(f),std::vector<cpp2::i32>>), "`T` is non-deducible.");
+}
+{
+auto f = []<typename T>(std::vector<std::vector<T>> const& x) -> void{};
+
+#line 28 "pure2-bugfix-for-deducible-parameters.cpp2"
+    static_assert(std::is_invocable_v<decltype(std::move(f)),std::vector<std::vector<cpp2::i32>>>, "`T` is deducible.");
+}
+#line 29 "pure2-bugfix-for-deducible-parameters.cpp2"
+}
+
+#line 32 "pure2-bugfix-for-deducible-parameters.cpp2"
+  template <typename T> v<T>::v(T const& x){}
+#line 32 "pure2-bugfix-for-deducible-parameters.cpp2"
+  template <typename T> auto v<T>::operator=(T const& x) -> v& {
+                                  return *this;
+#line 32 "pure2-bugfix-for-deducible-parameters.cpp2"
+  }
+

regression-tests/test-results/pure2-bugfix-for-deducible-parameters.cpp2.output

@@ -0,0 +1,2 @@
+pure2-bugfix-for-deducible-parameters.cpp2... ok (all Cpp2, passes safety checks)
+

regression-tests/test-results/pure2-bugfix-for-dependent-types-recursion.cpp

@@ -0,0 +1,24 @@
+
+#define CPP2_IMPORT_STD          Yes
+
+//=== Cpp2 type declarations ====================================================
+
+
+#include "cpp2util.h"
+
+
+
+//=== Cpp2 type definitions and function declarations ===========================
+
+auto main() -> int;
+
+
+//=== Cpp2 function definitions =================================================
+
+auto main() -> int{
+  using a = b;
+  using b = a;
+  static_cast<void>(a::t);
+  static_cast<void>(b::t);
+}
+

regression-tests/test-results/pure2-bugfix-for-dependent-types-recursion.cpp2.output

@@ -0,0 +1,2 @@
+pure2-bugfix-for-dependent-types-recursion.cpp2... ok (all Cpp2, passes safety checks)
+

regression-tests/test-results/pure2-bugfix-for-dependent-types.cpp

@@ -0,0 +1,122 @@
+
+#define CPP2_IMPORT_STD          Yes
+
+//=== Cpp2 type declarations ====================================================
+
+
+#include "cpp2util.h"
+
+
+#line 47 "pure2-bugfix-for-dependent-types.cpp2"
+template<typename T> class t;
+
+
+//=== Cpp2 type definitions and function declarations ===========================
+
+template<typename T> using identity = T;
+
+template<typename T, T::value_type V> [[nodiscard]] auto f(cpp2::in<typename T::value_type> x) -> T::value_type;
+
+
+#line 47 "pure2-bugfix-for-dependent-types.cpp2"
+template<typename T> class t {
+struct u_x_as_base { T::value_type x; };
+
+#line 48 "pure2-bugfix-for-dependent-types.cpp2"
+  public: class u: public u_x_as_base, public T::type {
+
+#line 51 "pure2-bugfix-for-dependent-types.cpp2"
+  };
+  public: T::value_type x {0}; 
+};
+
+auto main() -> int;
+
+
+//=== Cpp2 function definitions =================================================
+
+
+#line 3 "pure2-bugfix-for-dependent-types.cpp2"
+template<typename T, T::value_type V> [[nodiscard]] auto f(cpp2::in<typename T::value_type> x) -> T::value_type{
+  cpp2::Default.expects(cpp2::is<typename T::value_type>(x), "");
+  cpp2::deferred_init<typename T::value_type> y; 
+  y.construct(x);
+  using z = T::value_type;
+  return { typename T::value_type{x} }; 
+
+  // Dependent *template-id*s.
+  static_cast<void>(typename identity<T>::value_type{});// First identifier.
+  static_cast<void>(typename std::optional<T>::value_type{});// Non-first identifier.
+  static_cast<void>(typename std::array<cpp2::i32,T::value>::value_type{});
+  static_cast<void>(typename std::array<cpp2::i32,T::value + T::value>::value_type{});
+
+  // Emitted `template`.
+  using ptr = T*;    // Also test lookup through type aliases.
+  using nptr = cpp2::i32*;
+  static_cast<void>(typename std::pointer_traits<ptr>::template rebind<ptr>{});// Type-only context.
+  static_cast<void>(std::pointer_traits<nptr>::rebind<nptr>{});// Non-dependent.
+  static_cast<void>(std::pointer_traits<nptr>::rebind<ptr>{});// Dependent on the nested template.
+  static_cast<void>(typename std::pointer_traits<ptr>::template rebind<nptr>{});// Dependent on the outer template.
+  // _ = :identity<typename std::pointer_traits<ptr>::rebind<ptr>> = (); // Non type-only context. Blocked on #727.
+
+  // Aliases.
+  using w = T;
+  static_cast<void>(typename w::value_type{x});
+  using v = w;
+  static_cast<void>(typename v::value_type{x});
+  using a = T::type;
+  static_cast<void>(typename a::value_type{x});
+
+  {
+    // Test that there's no prefixed `typename` to....
+    static_cast<void>(std::integral_constant<cpp2::i32,T::value>());// `T::value`.
+    static_cast<void>(std::type_identity_t<T>{});// `std::type_identity_t<T>`.
+
+    // Test that non-dependent names aren't emitted with `typename`.
+    using a = std::integral_constant<cpp2::i32,0>;
+    using b = a;
+    using c = b;
+    static_cast<void>(b::value_type{x});
+    static_cast<void>(c::value_type{x});
+  }
+}
+
+#line 55 "pure2-bugfix-for-dependent-types.cpp2"
+auto main() -> int{
+  using zero = std::integral_constant<cpp2::i32,0>;
+  static_cast<void>(f<zero,0>(0));
+
+  // clang-format off
+  static_cast<void>(::t<zero>{});// clang-format on
+
+  // Emitted `template` (noop, taken care of by the UFCS macro).
+  static_cast<void>([](auto const& f) -> void{static_cast<void>(CPP2_UFCS_TEMPLATE_0(operator(), (<cpp2::i32>), f)); }([]<typename T>() -> void{}));
+
+  // Nesting is not relevant to lookup.
+  static_cast<void>([]<typename T>() -> void{static_cast<void>(typename T::value_type{}); });
+  static_cast<void>([]() -> void{static_cast<void>([]<typename T>() -> void{static_cast<void>(typename T::value_type{}); }); });
+  static_cast<void>([]() -> void{static_cast<void>([]() -> void{static_cast<void>([]<typename T>() -> void{static_cast<void>(typename T::value_type{}); }); }); });
+  static_cast<void>([]() -> void{static_cast<void>([]() -> void{static_cast<void>([]() -> void{static_cast<void>([]<typename T>() -> void{static_cast<void>(typename T::value_type{}); }); }); }); });
+  static_cast<void>([]() -> void{static_cast<void>([]() -> void{static_cast<void>([]<typename T>() -> void{static_cast<void>([]() -> void{static_cast<void>(typename T::value_type{}); }); }); }); });
+  static_cast<void>([]() -> void{static_cast<void>([]<typename T>() -> void{static_cast<void>([]() -> void{static_cast<void>([]() -> void{static_cast<void>(typename T::value_type{}); }); }); }); });
+  static_cast<void>([]<typename T>() -> void{static_cast<void>([]() -> void{static_cast<void>([]() -> void{static_cast<void>([]() -> void{static_cast<void>(typename T::value_type{}); }); }); }); });
+  static_cast<void>([]<typename T>() -> void{static_cast<void>([]() -> void{static_cast<void>([]() -> void{static_cast<void>([](cpp2::in<typename T::value_type> x) -> void{}); }); }); });
+  static_cast<void>([]<typename T>() -> void{static_cast<void>([]() -> void{static_cast<void>([](cpp2::in<typename T::value_type> x) -> void{static_cast<void>([]() -> void{}); }); }); });
+  static_cast<void>([]<typename T>() -> void{static_cast<void>([](cpp2::in<typename T::value_type> x) -> void{static_cast<void>([]() -> void{static_cast<void>([]() -> void{}); }); }); });
+  static_cast<void>([]<typename T>(cpp2::in<typename T::value_type> x) -> void{static_cast<void>([]() -> void{static_cast<void>([]() -> void{static_cast<void>([]() -> void{}); }); }); });
+
+  // Lookup.
+  {
+    using alias = std::integral_constant<cpp2::i32,0>;
+    static_cast<void>(alias::value_type{0});// Non-dependent.
+  }
+  static_cast<void>([]<typename T>([[maybe_unused]] T const& param1) -> void{
+    using alias = std::integral_constant<T,0>;
+    static_cast<void>(typename alias::value_type{0});// Dependent.
+    {
+      using alias = std::integral_constant<cpp2::i32,0>;
+      static_cast<void>(typename alias::value_type{0});// Non-dependent.
+    }
+  }(0));
+}
+

regression-tests/test-results/pure2-bugfix-for-dependent-types.cpp2.output

@@ -0,0 +1,2 @@
+pure2-bugfix-for-dependent-types.cpp2... ok (all Cpp2, passes safety checks)
+