[BUG] Argument list parentheses kept in non-local initialization

[JohelEGP]

Title: Argument list parentheses kept in non-local initialization.

Minimal reproducer (https://cpp2.godbolt.org/z/7Gcvzzov8):

u: type == std::array<i32, 2>;
t: @struct type = {
  this: std::integral_constant<u, :u = (17, 29)>;
}
main: () = _ = :u = (17, 29);;

Commands:

cppfront main.cpp2
clang++17 -std=c++23 -stdlib=libc++ -lc++abi -pedantic-errors -Wall -Wextra -Wconversion -fsanitize=undefined -Werror=unused-result -I . main.cpp

Expected result: No warnings; same as the u in main.

Actual result and error:

Cpp2 lowered to Cpp1:

//=== Cpp2 type declarations ====================================================


#include "cpp2util.h"


class t;
  

//=== Cpp2 type definitions and function declarations ===========================

using u = std::array<cpp2::i32,2>;
class t: public std::integral_constant<u,u{(17, 29)}> {

};
auto main() -> int;


//=== Cpp2 function definitions =================================================


auto main() -> int { static_cast<void>(u{17, 29});  }

Output:

main.cpp2:2:45: warning: left operand of comma operator has no effect [-Wunused-value]
    2 | class t: public std::integral_constant<u,u{(17, 29)}> {
      |                                             ^~
1 warning generated.

[JohelEGP]

This is just a duplicate of #503.

[jcanizales]

main: () = _ = :u = (17, 29);;

What is the meaning of this?

[JohelEGP]

If you mean the extra semicolon, there's a few open bugs in the area: https://github.com/hsutter/cppfront/issues?q=is%3Aissue+is%3Aopen+unnamed+declaration+in%3Atitle+.
#479 is also related, see in particuar: https://github.com/hsutter/cppfront/pull/479/files#diff-43ba71198da8225f205041c699dba495883d7d416c0b58916bf226aae97bafaeR4069-R4071.
I haven't reported this particular instance, yet. Maybe it'd be a duplicate of another one.

Otherwise,
we're discarding (_ =) an unnamed declaration of u initialized with (17, 29)
in main's expression-statement's body.

[JohelEGP]

Opened #611 for that now.

[jcanizales]

Thanks for the explanation!