[PATCH] Allow subscripting raw pointers

[Manish Goregaokar <manish@mozilla.com>]

This will be useful for dealing with vectors; regardless of our final solution
for the Index trait.

Right now subscripting vectors requires dancing between C and Rust mode.

2016-07-04  Manish Goregaokar  <manish@mozilla.com>

gdb/ChangeLog:
    * rust-lang.c (rust_subscript): Allow subscripting pointers

gdb/testsuite/ChangeLog:
    * simple.rs: Add test for raw pointer subscripting
    * simple.exp: Add test expectations
---
 gdb/rust-lang.c                   | 6 ++++++
 gdb/testsuite/gdb.rust/simple.exp | 1 +
 gdb/testsuite/gdb.rust/simple.rs  | 1 +
 3 files changed, 8 insertions(+)

diff --git a/gdb/rust-lang.c b/gdb/rust-lang.c
index 1849349..17b20c6 100644
--- a/gdb/rust-lang.c
+++ b/gdb/rust-lang.c
@@ -1415,6 +1415,12 @@ rust_subscript (struct expression *exp, int
*pos, enum noside noside,
       low_bound = 0;
       high_bound = value_as_long (len);
     }
+      else if (TYPE_CODE (type) == TYPE_CODE_PTR)
+    {
+      base = lhs;
+      low_bound = 0;
+      high_bound = LONGEST_MAX;
+    }
       else
     error (_("Cannot subscript non-array type"));

diff --git a/gdb/testsuite/gdb.rust/simple.exp
b/gdb/testsuite/gdb.rust/simple.exp
index 4622f75..32b3785 100644
--- a/gdb/testsuite/gdb.rust/simple.exp
+++ b/gdb/testsuite/gdb.rust/simple.exp
@@ -73,6 +73,7 @@ gdb_test "print w" " = \\\[1, 2, 3, 4\\\]"
 gdb_test "ptype w" " = \\\[i32; 4\\\]"
 gdb_test "print w\[2\]" " = 3"
 gdb_test "print w\[2\] @ 2" " = \\\[3, 4\\\]"
+gdb_test "print w_ptr\[2\]" " = 3"
 gdb_test "print fromslice" " = 3"
 gdb_test "print slice\[0\]" " = 3"
 gdb_test "print slice as &\[i32\]\[0\]" " = 3"
diff --git a/gdb/testsuite/gdb.rust/simple.rs b/gdb/testsuite/gdb.rust/simple.rs
index 3d28e27..4980826 100644
--- a/gdb/testsuite/gdb.rust/simple.rs
+++ b/gdb/testsuite/gdb.rust/simple.rs
@@ -87,6 +87,7 @@ fn main () {

     let v = Something::Three;
     let w = [1,2,3,4];
+    let w_ptr = &w[0];
     let x = (23, 25.5);
     let y = HiBob {field1: 7, field2: 8};
     let z = ByeBob(7, 8);
-- 
2.8.3