Account for pub in const -> static suggestion

Author: estebank

src/librustc_lint/builtin.rs

@@ -1214,8 +1214,13 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidNoMangleItems {
                     // don't have anything to attach a symbol to
                     let msg = "const items should never be #[no_mangle]";
                     let mut err = cx.struct_span_lint(NO_MANGLE_CONST_ITEMS, it.span, msg);
+
+                    // account for "pub const" (#45562)
+                    let start = cx.tcx.sess.codemap().span_to_snippet(it.span)
+                        .map(|snippet| snippet.find("const").unwrap_or(0))
+                        .unwrap_or(0) as u32;
                     // `const` is 5 chars
-                    let const_span = it.span.with_hi(BytePos(it.span.lo().0 + 5));
+                    let const_span = it.span.with_hi(BytePos(it.span.lo().0 + start + 5));
                     err.span_suggestion(const_span,
                                         "try a static value",
                                         "pub static".to_owned());

src/test/ui/suggestions/issue-45562.rs

@@ -0,0 +1,14 @@
+// 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.
+
+#[no_mangle] pub const RAH: usize = 5;
+//~^ ERROR const items should never be #[no_mangle]
+
+fn main() {}

src/test/ui/suggestions/issue-45562.stderr

@@ -0,0 +1,12 @@
+error: const items should never be #[no_mangle]
+  --> $DIR/issue-45562.rs:11:14
+   |
+11 | #[no_mangle] pub const RAH: usize = 5;
+   |              ---------^^^^^^^^^^^^^^^^
+   |              |
+   |              help: try a static value: `pub static`
+   |
+   = note: #[deny(no_mangle_const_items)] on by default
+
+error: aborting due to previous error
+