Merge #814

814: Set TREE_ADDRESSABLE when we need to borrow any expression r=philberty a=philberty

GCC requires VAR_DECL's and PARAM_DECL's to be marked with TREE_ADDRESSABLE
when the declaration will be used in borrow's ('&' getting the address).
This takes into account the implicit addresses when we do autoderef in
method resolution/operator-overloading.

If it is not set we end up in cases like this:

```c
i32 main ()
{
  i32 a.1;
  i32 D.86;
  i32 a;

  a = 1;
  a.1 = a; // this is wrong
  <i32 as AddAssign>::add_assign (&a.1, 2);
  D.86 = 0;
  return D.86;
}
```

You can see GCC will automatically make a copy of the VAR_DECL resulting bad code-generation.

Fixes #804


Co-authored-by: Philip Herron <philip.herron@embecosm.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/gcc/rust/hir/tree/rust-hir-item.h b/gcc/rust/hir/tree/rust-hir-item.h
index 0dd7ac8..99a3c48 100644
--- a/gcc/rust/hir/tree/rust-hir-item.h
+++ b/gcc/rust/hir/tree/rust-hir-item.h
@@ -560,7 +560,7 @@ public:
 
   Type *get_type () { return type.get (); }
 
-  Analysis::NodeMapping &get_mappings () { return mappings; }
+  const Analysis::NodeMapping &get_mappings () const { return mappings; }
 };
 
 // Visibility of item - if the item has it, then it is some form of public