Add line numbers and columns to error messages spanning multiple files

src/librustc_errors/emitter.rs

@@ -1013,8 +1013,21 @@ impl EmitterWriter {
 
                 // Then, the secondary file indicator
                 buffer.prepend(buffer_msg_line_offset + 1, "::: ", Style::LineNumber);
+                let loc = if let Some(first_line) = annotated_file.lines.first() {
+                    let col = if let Some(first_annotation) = first_line.annotations.first() {
+                        format!(":{}", first_annotation.start_col + 1)
+                    } else {
+                        "".to_string()
+                    };
+                    format!("{}:{}{}",
+                            annotated_file.file.name,
+                            cm.doctest_offset_line(first_line.line_index),
+                            col)
+                } else {
+                    annotated_file.file.name.to_string()
+                };
                 buffer.append(buffer_msg_line_offset + 1,
-                              &annotated_file.file.name.to_string(),
+                              &loc,
                               Style::LineAndColumn);
                 for _ in 0..max_line_num_len {
                     buffer.prepend(buffer_msg_line_offset + 1, " ", Style::NoStyle);

src/librustc_errors/snippet.rs

@@ -27,7 +27,8 @@ pub struct FileInfo {
 
     /// The "primary file", if any, gets a `-->` marker instead of
     /// `>>>`, and has a line-number/column printed and not just a
-    /// filename.  It appears first in the listing. It is known to
+    /// filename (other files are not guaranteed to have line numbers
+    /// or columns). It appears first in the listing. It is known to
     /// contain at least one primary span, though primary spans (which
     /// are designated with `^^^`) may also occur in other files.
     primary_span: Option<Span>,

src/test/ui/cross-file-errors/main.rs

@@ -0,0 +1,16 @@
+// Copyright 2018 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.
+
+#[macro_use]
+mod underscore;
+
+fn main() {
+    underscore!();
+}

src/test/ui/cross-file-errors/main.stderr

@@ -0,0 +1,11 @@
+error: expected expression, found `_`
+  --> $DIR/underscore.rs:18:9
+   |
+18 |         _
+   |         ^
+   | 
+  ::: $DIR/main.rs:15:5
+   |
+15 |     underscore!();
+   |     -------------- in this macro invocation
+

src/test/ui/cross-file-errors/underscore.rs

@@ -0,0 +1,20 @@
+// Copyright 2018 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.
+
+// We want this file only so we can test cross-file error
+// messages, but we don't want it in an external crate.
+// ignore-test
+#![crate_type = "lib"]
+
+macro_rules! underscore {
+    () => (
+        _
+    )
+}

src/test/ui/macro_backtrace/main.stderr

@@ -22,7 +22,7 @@ error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found
 27 |       ping!();
    |       -------- in this macro invocation
    | 
-  ::: <ping macros>
+  ::: <ping macros>:1:1
    |
 1  |   (  ) => { pong ! (  ) ; }
    |   -------------------------
@@ -42,31 +42,31 @@ error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found
 28 |       deep!();
    |       -------- in this macro invocation (#1)
    | 
-  ::: <deep macros>
+  ::: <deep macros>:1:1
    |
 1  |   (  ) => { foo ! (  ) ; }
    |   ------------------------
    |   |         |
    |   |         in this macro invocation (#2)
    |   in this expansion of `deep!` (#1)
    | 
-  ::: <foo macros>
+  ::: <foo macros>:1:1
    |
 1  |   (  ) => { bar ! (  ) ; }
    |   ------------------------
    |   |         |
    |   |         in this macro invocation (#3)
    |   in this expansion of `foo!` (#2)
    | 
-  ::: <bar macros>
+  ::: <bar macros>:1:1
    |
 1  |   (  ) => { ping ! (  ) ; }
    |   -------------------------
    |   |         |
    |   |         in this macro invocation (#4)
    |   in this expansion of `bar!` (#3)
    | 
-  ::: <ping macros>
+  ::: <ping macros>:1:1
    |
 1  |   (  ) => { pong ! (  ) ; }
    |   -------------------------

src/tools/compiletest/src/runtest.rs

@@ -1402,7 +1402,7 @@ impl<'test> TestCx<'test> {
     }
 
     /// For each `aux-build: foo/bar` annotation, we check to find the
-    /// file in a `aux` directory relative to the test itself.
+    /// file in a `auxiliary` directory relative to the test itself.
     fn compute_aux_test_paths(&self, rel_ab: &str) -> TestPaths {
         let test_ab = self.testpaths
             .file