aya-tool: enable clang_macro_fallback

[tamird]

Closes #1128.

cc @cppcoffee would you mind testing?

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[cppcoffee]

The input file content is as follows:

enum { FRAME_TYPE, FRAME_TYPEP, FRAME_LUA };

#define frame_type(f) ((f) & FRAME_TYPE)

The command output is:

# ./target/debug/aya-tool generate --header /tmp/test.h
/* automatically generated by rust-bindgen 0.71.1 */

pub mod _bindgen_ty_1 {
    pub type Type = ::aya_ebpf::cty::c_uint;
    pub const FRAME_TYPE: Type = 0;
    pub const FRAME_TYPEP: Type = 1;
    pub const FRAME_LUA: Type = 2;
}

It also printed debug information to the command line:

bindgen "/tmp/.tmpxaX8ll/test.h" ["--default-enum-style", "moduleconsts", "--no-layout-tests", "--no-derive-default", "--use-core", "--ctypes-prefix", "::aya_ebpf::cty", "--generate", "functions,types,vars,methods,constructors,destructors", "--no-doc-comments", "--no-prepend-enum-name", "--rust-target", "1.82.0", "--clang-macro-fallback", "--", "-Wno-unknown-attributes"]

Only the enum definitions were generated; the macro definitions were not generated.

[tamird]

Thanks for testing. I don't know what more we can do here. Perhaps this should be a bug report for rust-bindgen?

[cppcoffee]

Reported to rust-bindgen:

rust-lang/rust-bindgen#3065