From 030987481b339616954d36b4c421e86077f00e75 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Tue, 18 Dec 2018 23:43:00 +0000
Subject: [PATCH] Fix string for array access suggestion

---
 src/librustc_typeck/check/mod.rs                  | 4 +++-
 src/test/ui/parenthesised-deref-suggestion.rs     | 3 +++
 src/test/ui/parenthesised-deref-suggestion.stderr | 9 +++++++++
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 500bdbf6acd8..2f6de21d884f 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -3372,7 +3372,9 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                             len.assert_usize(self.tcx),
                             field.as_str().parse::<u64>()
                         ) {
-                            let base = self.tcx.hir().node_to_pretty_string(base.id);
+                            let base = self.tcx.sess.source_map()
+                                .span_to_snippet(base.span)
+                                .unwrap_or_else(|_| self.tcx.hir().node_to_pretty_string(base.id));
                             let help = "instead of using tuple indexing, use array indexing";
                             let suggestion = format!("{}[{}]", base, field);
                             let applicability = if len < user_index {
diff --git a/src/test/ui/parenthesised-deref-suggestion.rs b/src/test/ui/parenthesised-deref-suggestion.rs
index bcbb51ccd6b6..0b4ccdd5a56d 100644
--- a/src/test/ui/parenthesised-deref-suggestion.rs
+++ b/src/test/ui/parenthesised-deref-suggestion.rs
@@ -5,4 +5,7 @@ struct Session {
 fn main() {
     let sess: &Session = &Session { opts: 0 };
     (sess as *const Session).opts; //~ ERROR no field `opts` on type `*const Session`
+
+    let x = [0u32];
+    (x as [u32; 1]).0; //~ ERROR no field `0` on type `[u32; 1]`
 }
diff --git a/src/test/ui/parenthesised-deref-suggestion.stderr b/src/test/ui/parenthesised-deref-suggestion.stderr
index 2e122f38f385..71a2bf67f06a 100644
--- a/src/test/ui/parenthesised-deref-suggestion.stderr
+++ b/src/test/ui/parenthesised-deref-suggestion.stderr
@@ -7,6 +7,15 @@ help: `(sess as *const Session)` is a raw pointer; try dereferencing it
    |
 LL |     (*(sess as *const Session)).opts; //~ ERROR no field `opts` on type `*const Session`
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0609]: no field `0` on type `[u32; 1]`
+  --> $DIR/parenthesised-deref-suggestion.rs:10:21
+   |
+LL |     (x as [u32; 1]).0; //~ ERROR no field `0` on type `[u32; 1]`
+   |     ----------------^
+   |     |
+   |     help: instead of using tuple indexing, use array indexing: `(x as [u32; 1])[0]`
+
 error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0609`.