improve span of erroneous empty macro invocation

The ideas is to use the span of the complete macro invocation if the span of a
macro error is `DUMMY_SP`.

fixes rust-lang#7970

src/libsyntax/ext/tt/macro_parser.rs

@@ -249,22 +249,6 @@ pub enum ParseResult<T> {
 pub type NamedParseResult = ParseResult<HashMap<Ident, Rc<NamedMatch>>>;
 pub type PositionalParseResult = ParseResult<Vec<Rc<NamedMatch>>>;
 
-pub fn parse_or_else(sess: &ParseSess,
- cfg: ast::CrateConfig,
- rdr: TtReader,
- ms: Vec<TokenTree> )
- -> HashMap<Ident, Rc<NamedMatch>> {
- match parse(sess, cfg, rdr, &ms[..]) {
- Success(m) => m,
- Failure(sp, str) => {
- panic!(sess.span_diagnostic.span_fatal(sp, &str[..]))
- }
- Error(sp, str) => {
- panic!(sess.span_diagnostic.span_fatal(sp, &str[..]))
- }
- }
-}
-
 /// Perform a token equality check, ignoring syntax context (that is, an
 /// unhygienic comparison)
 pub fn token_name_eq(t1 : &Token, t2 : &Token) -> bool {

src/libsyntax/ext/tt/macro_rules.rs

@@ -14,7 +14,7 @@ use ext::base::{ExtCtxt, MacResult, SyntaxExtension};
 use ext::base::{NormalTT, TTMacroExpander};
 use ext::tt::macro_parser::{Success, Error, Failure};
 use ext::tt::macro_parser::{NamedMatch, MatchedSeq, MatchedNonterminal};
-use ext::tt::macro_parser::{parse, parse_or_else};
+use ext::tt::macro_parser::parse;
 use parse::lexer::new_tt_reader;
 use parse::parser::Parser;
 use parse::token::{self, special_idents, gensym_ident, NtTT, Token};
@@ -211,12 +211,23 @@ fn generic_extension<'cx>(cx: &'cx ExtCtxt,
  best_fail_spot = sp;
  best_fail_msg = (*msg).clone();
  },
- Error(sp, ref msg) => panic!(cx.span_fatal(sp, &msg[..]))
+ Error(mut spp, ref msg) => {
+ if spp == DUMMY_SP {
+ spp = sp;
+ }
+
+ panic!(cx.span_fatal(spp, &msg[..]))
+ }
  }
  }
  _ => cx.bug("non-matcher found in parsed lhses")
  }
  }
+
+ if best_fail_spot == DUMMY_SP {
+ best_fail_spot = sp;
+ }
+
  panic!(cx.span_fatal(best_fail_spot, &best_fail_msg[..]));
 }
 
@@ -266,10 +277,20 @@ pub fn compile<'cx>(cx: &'cx mut ExtCtxt,
  None,
  None,
  def.body.clone());
- let argument_map = parse_or_else(cx.parse_sess(),
- cx.cfg(),
- arg_reader,
- argument_gram);
+
+ let argument_map = match parse(cx.parse_sess(),
+ cx.cfg(),
+ arg_reader,
+ &argument_gram) {
+ Success(m) => m,
+ Failure(mut sp, str) | Error(mut sp, str) => {
+ if sp == DUMMY_SP {
+ sp = def.span;
+ }
+
+ panic!(cx.parse_sess().span_diagnostic.span_fatal(sp, &str[..]));
+ }
+ };
 
  // Extract the arguments:
  let lhses = match **argument_map.get(&lhs_nm).unwrap() {

src/test/compile-fail/issue-7970a.rs

@@ -0,0 +1,14 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+ println!();
+ //~^ ERROR unexpected end of macro invocation
+}

src/test/compile-fail/issue-7970b.rs

@@ -0,0 +1,14 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {}
+
+macro_rules! test {}
+//~^ ERROR unexpected end of macro invocation