proc macros 1.1: improve diagnostics

src/libsyntax/fold.rs

@@ -542,19 +542,19 @@ pub fn noop_fold_arg<T: Folder>(Arg {id, pat, ty}: Arg, fld: &mut T) -> Arg {
 pub fn noop_fold_tt<T: Folder>(tt: &TokenTree, fld: &mut T) -> TokenTree {
     match *tt {
         TokenTree::Token(span, ref tok) =>
-            TokenTree::Token(span, fld.fold_token(tok.clone())),
+            TokenTree::Token(fld.new_span(span), fld.fold_token(tok.clone())),
         TokenTree::Delimited(span, ref delimed) => {
-            TokenTree::Delimited(span, Rc::new(
+            TokenTree::Delimited(fld.new_span(span), Rc::new(
                             Delimited {
                                 delim: delimed.delim,
-                                open_span: delimed.open_span,
+                                open_span: fld.new_span(delimed.open_span),
                                 tts: fld.fold_tts(&delimed.tts),
-                                close_span: delimed.close_span,
+                                close_span: fld.new_span(delimed.close_span),
                             }
                         ))
         },
         TokenTree::Sequence(span, ref seq) =>
-            TokenTree::Sequence(span,
+            TokenTree::Sequence(fld.new_span(span),
                        Rc::new(SequenceRepetition {
                            tts: fld.fold_tts(&seq.tts),
                            separator: seq.separator.clone().map(|tok| fld.fold_token(tok)),
@@ -647,7 +647,7 @@ pub fn noop_fold_fn_decl<T: Folder>(decl: P<FnDecl>, fld: &mut T) -> P<FnDecl> {
         inputs: inputs.move_map(|x| fld.fold_arg(x)),
         output: match output {
             FunctionRetTy::Ty(ty) => FunctionRetTy::Ty(fld.fold_ty(ty)),
-            FunctionRetTy::Default(span) => FunctionRetTy::Default(span),
+            FunctionRetTy::Default(span) => FunctionRetTy::Default(fld.new_span(span)),
         },
         variadic: variadic
     })
@@ -674,7 +674,7 @@ pub fn noop_fold_ty_param<T: Folder>(tp: TyParam, fld: &mut T) -> TyParam {
         ident: fld.fold_ident(ident),
         bounds: fld.fold_bounds(bounds),
         default: default.map(|x| fld.fold_ty(x)),
-        span: span
+        span: fld.new_span(span),
     }
 }
 

src/test/compile-fail-fulldeps/proc-macro/auxiliary/issue_38586.rs

@@ -0,0 +1,22 @@
+// Copyright 2016 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.
+
+// force-host
+// no-prefer-dynamic
+
+#![feature(proc_macro, proc_macro_lib)]
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+
+#[proc_macro_derive(A)]
+pub fn derive_a(_: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    "fn f() { println!(\"{}\", foo); }".parse().unwrap()
+}

src/test/compile-fail-fulldeps/proc-macro/issue-38586.rs

@@ -0,0 +1,21 @@
+// Copyright 2016 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.
+
+// aux-build:issue_38586.rs
+
+#![feature(proc_macro)]
+
+#[macro_use]
+extern crate issue_38586;
+
+#[derive(A)] //~ ERROR `foo`
+struct A;
+
+fn main() {}