`include_str` does not output an error when the file is missing

I tried this code:

#![feature(rustc_attrs)]

#[rustc_builtin_macro]
macro_rules! include_str {
    () => {{}};
}

macro_rules! file1 {
    () => {
        "missing_file.in"
    };
}

fn main() {
    include_str!(file1!(),); 
}

(note the trailing comma in the include_str macro invocation)

I expected to see this happen: Gccrs output an error message such like rustc.

error: couldn't read missing_file.in: No such file or directory (os error 2)

Instead, this happened: explanation

No error, simply expand the macro to an empty fragment.

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• fb1259001c2

Start by running the supplied Rust reproduction with gccrs and compare its behavior with rustc. Trace the include_str builtin macro expansion, especially the trailing-comma case and missing-file handling; done means gccrs emits a diagnostic for missing_file.in rather than expanding to an empty fragment.