From 3e7a4ca2f1d576a4a23e8c541cb5c0c420b108de Mon Sep 17 00:00:00 2001
From: Oliver Scherer <github35764891676564198441@oli-obk.de>
Date: Mon, 17 Dec 2018 16:47:26 +0100
Subject: [PATCH 1/2] Remove a wrong multiplier on relocation offset
 computation

---
 src/librustc_mir/interpret/memory.rs      | 8 ++++----
 src/test/ui/consts/promoted_regression.rs | 9 +++++++++
 2 files changed, 13 insertions(+), 4 deletions(-)
 create mode 100644 src/test/ui/consts/promoted_regression.rs

diff --git a/src/librustc_mir/interpret/memory.rs b/src/librustc_mir/interpret/memory.rs
index 420fe26426321..65347a02be0c7 100644
--- a/src/librustc_mir/interpret/memory.rs
+++ b/src/librustc_mir/interpret/memory.rs
@@ -707,10 +707,10 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> Memory<'a, 'mir, 'tcx, M> {
                 new_relocations.extend(
                     relocations
                     .iter()
-                    .map(|&(offset, reloc)| {
-                    (offset + dest.offset - src.offset + (i * size * relocations.len() as u64),
-                     reloc)
-                    })
+                    .map(|&(offset, reloc)| (
+                        offset + dest.offset - src.offset + (i * size),
+                        reloc,
+                    ))
                 );
             }
 
diff --git a/src/test/ui/consts/promoted_regression.rs b/src/test/ui/consts/promoted_regression.rs
new file mode 100644
index 0000000000000..68b9a20ecf90b
--- /dev/null
+++ b/src/test/ui/consts/promoted_regression.rs
@@ -0,0 +1,9 @@
+// compile-pass
+
+fn main() {
+    let _ = &[("", ""); 3];
+}
+
+const FOO: &[(&str, &str)] = &[("", ""); 3];
+const BAR: &[(&str, &str); 5] = &[("", ""); 5];
+const BAA: &[[&str; 12]; 11] = &[[""; 12]; 11];

From 50eb5f6137719a7e8fdd270e90af0d734d002c5d Mon Sep 17 00:00:00 2001
From: Oliver Scherer <github35764891676564198441@oli-obk.de>
Date: Tue, 18 Dec 2018 10:08:37 +0100
Subject: [PATCH 2/2] Explain the math

---
 src/librustc_mir/interpret/memory.rs | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/librustc_mir/interpret/memory.rs b/src/librustc_mir/interpret/memory.rs
index 65347a02be0c7..77a5f5d7b3a84 100644
--- a/src/librustc_mir/interpret/memory.rs
+++ b/src/librustc_mir/interpret/memory.rs
@@ -707,10 +707,15 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> Memory<'a, 'mir, 'tcx, M> {
                 new_relocations.extend(
                     relocations
                     .iter()
-                    .map(|&(offset, reloc)| (
-                        offset + dest.offset - src.offset + (i * size),
-                        reloc,
-                    ))
+                    .map(|&(offset, reloc)| {
+                        // compute offset for current repetition
+                        let dest_offset = dest.offset + (i * size);
+                        (
+                            // shift offsets from source allocation to destination allocation
+                            offset + dest_offset - src.offset,
+                            reloc,
+                        )
+                    })
                 );
             }