Rollup merge of #47780 - varkor:cross-file-errors-line-col, r=estebank

Add line numbers and columns to error messages spanning multiple files

If an error message is emitted that spans several files, only the
primary file currently has line and column data attached. This is
useful information, even in files other than the one in which the error
occurs. We can often work out which line and column the error
corresponds to in other files — in this case it is helpful to add them
(in the case of ambiguity, the first relevant line/column is picked,
which is still helpful than none).

4 files changed, 52 insertions, 5 deletions

diff --git a/src/test/ui/cross-file-errors/main.rs b/src/test/ui/cross-file-errors/main.rs
new file mode 100644
index 00000000000..8eae79a21a9
--- /dev/null
+++ b/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!();
+}
diff --git a/src/test/ui/cross-file-errors/main.stderr b/src/test/ui/cross-file-errors/main.stderr
new file mode 100644
index 00000000000..a1cdae10edf
--- /dev/null
+++ b/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
+
diff --git a/src/test/ui/cross-file-errors/underscore.rs b/src/test/ui/cross-file-errors/underscore.rs
new file mode 100644
index 00000000000..312b3b8f4dd
--- /dev/null
+++ b/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 {
+    () => (
+        _
+    )
+}
diff --git a/src/test/ui/macro_backtrace/main.stderr b/src/test/ui/macro_backtrace/main.stderr
index 5990f71b3ca..48138ee711b 100644
--- a/src/test/ui/macro_backtrace/main.stderr
+++ b/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 ! (  ) ; }
    |   -------------------------
@@ -42,7 +42,7 @@ error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found
 28 |       deep!();
    |       -------- in this macro invocation (#1)
    | 
-  ::: <deep macros>
+  ::: <deep macros>:1:1
    |
 1  |   (  ) => { foo ! (  ) ; }
    |   ------------------------
@@ -50,7 +50,7 @@ error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found
    |   |         in this macro invocation (#2)
    |   in this expansion of `deep!` (#1)
    | 
-  ::: <foo macros>
+  ::: <foo macros>:1:1
    |
 1  |   (  ) => { bar ! (  ) ; }
    |   ------------------------
@@ -58,7 +58,7 @@ error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found
    |   |         in this macro invocation (#3)
    |   in this expansion of `foo!` (#2)
    | 
-  ::: <bar macros>
+  ::: <bar macros>:1:1
    |
 1  |   (  ) => { ping ! (  ) ; }
    |   -------------------------
@@ -66,7 +66,7 @@ error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found
    |   |         in this macro invocation (#4)
    |   in this expansion of `bar!` (#3)
    | 
-  ::: <ping macros>
+  ::: <ping macros>:1:1
    |
 1  |   (  ) => { pong ! (  ) ; }
    |   -------------------------