don't issue "expected statement after outer attr." after inner attr.

While an inner attribute here is in fact erroneous, that error ("inner
attribute is not permitted in this context") successfully gets set earlier;
this further admonition is nonsensical.

Resolves #45296.

Author: zackmdavis

src/libsyntax/parse/parser.rs

@@ -4088,11 +4088,11 @@ impl<'a> Parser<'a> {
                     node: StmtKind::Item(i),
                 },
                 None => {
-                    let unused_attrs = |attrs: &[_], s: &mut Self| {
+                    let unused_attrs = |attrs: &[Attribute], s: &mut Self| {
                         if !attrs.is_empty() {
                             if s.prev_token_kind == PrevTokenKind::DocComment {
                                 s.span_fatal_err(s.prev_span, Error::UselessDocComment).emit();
-                            } else {
+                            } else if attrs.iter().any(|a| a.style == AttrStyle::Outer) {
                                 s.span_err(s.span, "expected statement after outer attribute");
                             }
                         }

src/test/ui/issue-45296.rs

@@ -0,0 +1,15 @@
+// Copyright 2017 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() {
+    let unused = ();
+
+    #![allow(unused_variables)]
+}

src/test/ui/issue-45296.stderr

@@ -0,0 +1,11 @@
+error: an inner attribute is not permitted in this context
+  --> $DIR/issue-45296.rs:14:7
+   |
+14 |     #![allow(unused_variables)]
+   |       ^
+   |
+   = note: inner attributes and doc comments, like `#![no_std]` or `//! My crate`, annotate the item enclosing them, and are usually found at the beginning of source files. Outer attributes and doc comments, like `#[test]` and
+                                              `/// My function`, annotate the item following them.
+
+error: aborting due to previous error
+