klion26 commented on PR #9498: URL: https://github.com/apache/arrow-rs/pull/9498#issuecomment-3988097222
> I'm a bit surprised the duplication didn't trigger compiler errors? But removing it also doesn't trigger any errors, so LGTM. Tried that - Same macro will override the previous one (same as variable) - Function will throw an error [same macro](https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=39965d8396a186f18363c513fc2cfe65 ) ``` macro_rules! my_macro { () => { println!("first"); }; } macro_rules! my_macro { () => { println!("second"); }; } fn main() { my_macro!(); // 输出 "second" } ``` the output will be ``` warning: unused macro definition: `my_macro` --> src/main.rs:1:14 | 1 | macro_rules! my_macro { | ^^^^^^^^ | = note: `#[warn(unused_macros)]` (part of `#[warn(unused)]`) on by default warning: `playground` (bin "playground") generated 1 warning Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.79s Running `target/debug/playground` ``` [same fun](https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=94254bc70450d2c153e5f59f0eb3cde6) ``` fn my_fn() { println!("first"); } fn my_fn() { // 编译错误：the name `my_fn` is defined multiple times println!("second"); } fn main() { my_fn!(); } ``` will compile error ``` Compiling playground v0.0.1 (/playground) error[E0428]: the name `my_fn` is defined multiple times --> src/main.rs:5:1 | 1 | fn my_fn() { | ---------- previous definition of the value `my_fn` here ... 5 | fn my_fn() { // 编译错误：the name `my_fn` is defined multiple times | ^^^^^^^^^^ `my_fn` redefined here | = note: `my_fn` must be defined only once in the value namespace of this module error: cannot find macro `my_fn` in this scope --> src/main.rs:9:5 | 9 | my_fn!(); | ^^^^^ | = note: `my_fn` is in scope, but it is a function, not a macro For more information about this error, try `rustc --explain E0428`. error: could not compile `playground` (bin "playground") due to 2 previous errors ``` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
