Va list binding compatibility

[gerard-ryan-immersaview]

From what I can tell a va_list should be created by calling va_start and no documentation that I could find specifies the use of va_list as an argument explicitly.
Assuming this works, I imagine that some compilers happen to implement va_list and ... the same, but ... seems the be the specified way.

I haven't done any runtime testing of these changes, so if this is wrong I'd love to know why.

Sources:

• https://en.cppreference.com/w/c/language/variadic
• https://en.cppreference.com/w/cpp/language/variadic_arguments

Related: #968

Closes: #891

[emilio]

Tests are failing because:

Output failed to compile: Output { status: ExitStatus(unix_wait_status(256)), stdout: "", stderr: "/home/runner/work/cbindgen/cbindgen/target/package/cbindgen-0.26.0/tests/expectations/va_list.compat.c:6:32: error: ISO C requires a named argument before ‘...’\n    6 | typedef int32_t (*VaListFnPtr)(...);\n      |                                ^~~\n/home/runner/work/cbindgen/cbindgen/target/package/cbindgen-0.26.0/tests/expectations/va_list.compat.c:11:18: error: ISO C requires a named argument before ‘...’\n   11 |   int32_t (*fn1)(...);\n      |                  ^~~\n/home/runner/work/cbindgen/cbindgen/target/package/cbindgen-0.26.0/tests/expectations/va_list.compat.c:22:22: error: ISO C requires a named argument before ‘...’\n   22 | int32_t va_list_test(...);\n      |                      ^~~\n/home/runner/work/cbindgen/cbindgen/target/package/cbindgen-0.26.0/tests/expectations/va_list.compat.c:24:23: error: ISO C requires a named argument before ‘...’\n   24 | int32_t va_list_test2(...);\n      |                       ^~~\n/home/runner/work/cbindgen/cbindgen/target/package/cbindgen-0.26.0/tests/expectations/va_list.compat.c:26:37: error: ISO C requires a named argument before ‘...’\n   26 | void va_list_fn_ptrs(int32_t (*fn1)(...),\n      |                                     ^~~\ncc1: note: unrecognized command-line option ‘-Wno-return-type-c-linkage’ may have been intended to silence earlier diagnostics\n" }

Let's just add a dummy char* or somesuch argument to the function types?

In general this looks good. Could you clean up the commit history to avoid having reverts and so on if you don't mind? Thanks.

[emilio]

Also, in the commit messages and PR title, please use compatibility rather than compatability? I think the later is a typo (but not an english speaker so icbw)

[gerard-ryan-immersaview]

Tests are failing because:

Output failed to compile: Output { status: ExitStatus(unix_wait_status(256)), stdout: "", stderr: "/home/runner/work/cbindgen/cbindgen/target/package/cbindgen-0.26.0/tests/expectations/va_list.compat.c:6:32: error: ISO C requires a named argument before ‘...’\n    6 | typedef int32_t (*VaListFnPtr)(...);\n      |                                ^~~\n/home/runner/work/cbindgen/cbindgen/target/package/cbindgen-0.26.0/tests/expectations/va_list.compat.c:11:18: error: ISO C requires a named argument before ‘...’\n   11 |   int32_t (*fn1)(...);\n      |                  ^~~\n/home/runner/work/cbindgen/cbindgen/target/package/cbindgen-0.26.0/tests/expectations/va_list.compat.c:22:22: error: ISO C requires a named argument before ‘...’\n   22 | int32_t va_list_test(...);\n      |                      ^~~\n/home/runner/work/cbindgen/cbindgen/target/package/cbindgen-0.26.0/tests/expectations/va_list.compat.c:24:23: error: ISO C requires a named argument before ‘...’\n   24 | int32_t va_list_test2(...);\n      |                       ^~~\n/home/runner/work/cbindgen/cbindgen/target/package/cbindgen-0.26.0/tests/expectations/va_list.compat.c:26:37: error: ISO C requires a named argument before ‘...’\n   26 | void va_list_fn_ptrs(int32_t (*fn1)(...),\n      |                                     ^~~\ncc1: note: unrecognized command-line option ‘-Wno-return-type-c-linkage’ may have been intended to silence earlier diagnostics\n" }

Let's just add a dummy char* or somesuch argument to the function types?

Oh, I was wondering why this was compiling before, I just assumed it was using c23 like I was, but regardless, I fixed this now.

In general this looks good. Could you clean up the commit history to avoid having reverts and so on if you don't mind? Thanks.

I squashed all the commits except the code move commit because it makes the diffs nicer.

[kanru]

It looks like when used in function pointer the dotdotdot version does not emit the va args dots in the C version. Is this intended?

[kanru]

Created #971

[gerard-ryan-immersaview]

I added this test to highlight the existing limitation.
I had attempted to address it with #969 but there appears to have been some miscommunication.