rustc_builtin_macros/
compile_error.rs

1// The compiler code necessary to support the compile_error! extension.
2
3use rustc_ast::tokenstream::TokenStream;
4use rustc_expand::base::{DummyResult, ExpandResult, ExtCtxt, MacroExpanderResult};
5use rustc_span::Span;
6
7use crate::util::get_single_str_from_tts;
8
9pub(crate) fn expand_compile_error<'cx>(
10    cx: &'cx mut ExtCtxt<'_>,
11    sp: Span,
12    tts: TokenStream,
13) -> MacroExpanderResult<'cx> {
14    let ExpandResult::Ready(mac) = get_single_str_from_tts(cx, sp, tts, "compile_error!") else {
15        return ExpandResult::Retry(());
16    };
17    let var = match mac {
18        Ok(var) => var,
19        Err(guar) => return ExpandResult::Ready(DummyResult::any(sp, guar)),
20    };
21
22    #[expect(rustc::diagnostic_outside_of_impl, reason = "diagnostic message is specified by user")]
23    #[expect(rustc::untranslatable_diagnostic, reason = "diagnostic message is specified by user")]
24    let guar = cx.dcx().span_err(sp, var.to_string());
25
26    ExpandResult::Ready(DummyResult::any(sp, guar))
27}