Print the macro context name on incomplete parse

Fixes #22425

Also fixes #30007, since it's just a change from `true` to `false`.

src/test/compile-fail/invalid-macro-matcher.rs

@@ -9,7 +9,7 @@
 // except according to those terms.
 
 macro_rules! invalid {
-    _ => (); //~^ ERROR Invalid macro matcher
+    _ => (); //~^ ERROR invalid macro matcher
 }
 
 fn main() {

src/test/compile-fail/issue-30007.rs

@@ -0,0 +1,19 @@
+// 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.
+
+#![feature(type_macros)]
+
+macro_rules! t {
+    () => ( String ; );     //~ ERROR macro expansion ignores token `;`
+}
+
+fn main() {
+    let i: Vec<t!()>;       //~ NOTE caused by the macro expansion here
+}

src/test/compile-fail/macro-context.rs

@@ -0,0 +1,33 @@
+// 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.
+
+#![feature(type_macros)]
+
+// (typeof used because it's surprisingly hard to find an unparsed token after a stmt)
+macro_rules! m {
+    () => ( i ; typeof );   //~ ERROR `typeof` is a reserved keyword
+                            //~| ERROR macro expansion ignores token `typeof`
+                            //~| ERROR macro expansion ignores token `typeof`
+                            //~| ERROR macro expansion ignores token `;`
+                            //~| ERROR macro expansion ignores token `;`
+                            //~| ERROR macro expansion ignores token `i`
+}
+
+m!();               //~ NOTE the usage of `m!` is likely invalid in this item context
+
+fn main() {
+    let a: m!();    //~ NOTE the usage of `m!` is likely invalid in this type context
+    let i = m!();   //~ NOTE the usage of `m!` is likely invalid in this expression context
+    match 0 {
+        m!() => {}  //~ NOTE the usage of `m!` is likely invalid in this pattern context
+    }
+
+    m!();           //~ NOTE the usage of `m!` is likely invalid in this statement context
+}