compiler/rustc_builtin_macros/src/concat.rs

   1 use rustc_ast as ast;
   2 use rustc_ast::tokenstream::TokenStream;
   3 use rustc_expand::base::{self, DummyResult};
   4 use rustc_session::errors::report_lit_error;
   5 use rustc_span::symbol::Symbol;
   6
   7 pub fn expand_concat(
   8     cx: &mut base::ExtCtxt<'_>,
   9     sp: rustc_span::Span,
  10     tts: TokenStream,
  11 ) -> Box<dyn base::MacResult + 'static> {
  12     let Some(es) = base::get_exprs_from_tts(cx, tts) else {
  13         return DummyResult::any(sp);
  14     };
  15     let mut accumulator = String::new();
  16     let mut missing_literal = vec![];
  17     let mut has_errors = false;
  18     for e in es {
  19         match e.kind {
  20             ast::ExprKind::Lit(token_lit) => match ast::LitKind::from_token_lit(token_lit) {
  21                 Ok(ast::LitKind::Str(s, _) | ast::LitKind::Float(s, _)) => {
  22                     accumulator.push_str(s.as_str());
  23                 }
  24                 Ok(ast::LitKind::Char(c)) => {
  25                     accumulator.push(c);
  26                 }
  27                 Ok(ast::LitKind::Int(i, _)) => {
  28                     accumulator.push_str(&i.to_string());
  29                 }
  30                 Ok(ast::LitKind::Bool(b)) => {
  31                     accumulator.push_str(&b.to_string());
  32                 }
  33                 Ok(ast::LitKind::Byte(..) | ast::LitKind::ByteStr(..)) => {
  34                     cx.span_err(e.span, "cannot concatenate a byte string literal");
  35                     has_errors = true;
  36                 }
  37                 Ok(ast::LitKind::Err) => {
  38                     has_errors = true;
  39                 }
  40                 Err(err) => {
  41                     report_lit_error(&cx.sess.parse_sess, err, token_lit, e.span);
  42                     has_errors = true;
  43                 }
  44             },
  45             ast::ExprKind::IncludedBytes(..) => {
  46                 cx.span_err(e.span, "cannot concatenate a byte string literal")
  47             }
  48             ast::ExprKind::Err => {
  49                 has_errors = true;
  50             }
  51             _ => {
  52                 missing_literal.push(e.span);
  53             }
  54         }
  55     }
  56     if !missing_literal.is_empty() {
  57         let mut err = cx.struct_span_err(missing_literal, "expected a literal");
  58         err.note("only literals (like `\"foo\"`, `42` and `3.14`) can be passed to `concat!()`");
  59         err.emit();
  60         return DummyResult::any(sp);
  61     } else if has_errors {
  62         return DummyResult::any(sp);
  63     }
  64     let sp = cx.with_def_site_ctxt(sp);
  65     base::MacEager::expr(cx.expr_str(sp, Symbol::intern(&accumulator)))
  66 }