fix(cpp1): improve recognition of dependent types and deducible parameters

Author: JohelEGP

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

@@ -0,0 +1,34 @@
+// 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>> = ());
+  // Uncomment once `typename` is supported for template arguments.
+  // _ = :<T, U> (x: std::pair<T, typename U::value_type>, y: U) = {}(:std::pair = (0, 0), z);
+  _ = :<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>>);
+  (copy f := :<T> (x: std::vector<std::vector<T>>) = {})
+    static_assert(std::is_invocable_v<decltype(f), std::vector<std::vector<i32>>>);
+}
+
+v: <T> type = {
+  operator=: (out this, x: T) = { }
+}

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

@@ -0,0 +1,92 @@
+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;                                 // Needed, pending #502.
+  nptr: type == * i32;                               // Needed, pending #502.
+  _ = :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.
+  // Uncomment once `typename` is supported for template arguments.
+  // _ = :identity<typename std::pointer_traits<ptr>::rebind<ptr>> = (); // Non type-only context.
+
+  // 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 irrelevant.
+  _ = :<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/clang-18/clang-version.output

@@ -0,0 +1,4 @@
+clang version 18.0.0 (https://github.com/llvm/llvm-project.git 3723ede3cf5324827f8fbbe7f484c2ee4d7a7204)
+Target: x86_64-pc-linux-gnu
+Thread model: posix
+InstalledDir: /home/johel/root/clang-main/bin