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 use std::string::String;
   8
   9 pub fn expand_concat(
  10     cx: &mut base::ExtCtxt<'_>,
  11     sp: rustc_span::Span,
  12     tts: TokenStream,
  13 ) -> Box<dyn base::MacResult + 'static> {
  14     let Some(es) = base::get_exprs_from_tts(cx, sp, tts) else {
  15         return DummyResult::any(sp);
  16     };
  17     let mut accumulator = String::new();
  18     let mut missing_literal = vec![];
  19     let mut has_errors = false;
  20     for e in es {
  21         match e.kind {
  22             ast::ExprKind::Lit(token_lit) => match ast::LitKind::from_token_lit(token_lit) {
  23                 Ok(ast::LitKind::Str(ref s, _) | ast::LitKind::Float(ref s, _)) => {
  24                     accumulator.push_str(s.as_str());
  25                 }
  26                 Ok(ast::LitKind::Char(c)) => {
  27                     accumulator.push(c);
  28                 }
  29                 Ok(ast::LitKind::Int(i, _)) => {
  30                     accumulator.push_str(&i.to_string());
  31                 }
  32                 Ok(ast::LitKind::Bool(b)) => {
  33                     accumulator.push_str(&b.to_string());
  34                 }
  35                 Ok(ast::LitKind::Byte(..) | ast::LitKind::ByteStr(..)) => {
  36                     cx.span_err(e.span, "cannot concatenate a byte string literal");
  37                     has_errors = true;
  38                 }
  39                 Ok(ast::LitKind::Err) => {
  40                     has_errors = true;
  41                 }
  42                 Err(err) => {
  43                     report_lit_error(&cx.sess.parse_sess, err, token_lit, e.span);
  44                     has_errors = true;
  45                 }
  46             },
  47             ast::ExprKind::IncludedBytes(..) => {
  48                 cx.span_err(e.span, "cannot concatenate a byte string literal")
  49             }
  50             ast::ExprKind::Err => {
  51                 has_errors = true;
  52             }
  53             _ => {
  54                 missing_literal.push(e.span);
  55             }
  56         }
  57     }
  58     if !missing_literal.is_empty() {
  59         let mut err = cx.struct_span_err(missing_literal, "expected a literal");
  60         err.note("only literals (like `\"foo\"`, `42` and `3.14`) can be passed to `concat!()`");
  61         err.emit();
  62         return DummyResult::any(sp);
  63     } else if has_errors {
  64         return DummyResult::any(sp);
  65     }
  66     let sp = cx.with_def_site_ctxt(sp);
  67     base::MacEager::expr(cx.expr_str(sp, Symbol::intern(&accumulator)))
  68 }