Fix &str printing in Rust

Printing a string slice ("&str") in Rust would print until the
terminating \0; but that is incorrect because a slice has a length.
This fixes &str printing, and arranges to preserve the type name when
slicing a slice, so that printing a slice of an "&str" works as well.

This is PR rust/22236.

2017-10-02  Tom Tromey  <tom@tromey.com>

	PR rust/22236:
	* rust-lang.c (rust_val_print_str): New function.
	(val_print_struct): Call it.
	(rust_subscript): Preserve name of slice type.

2017-10-02  Tom Tromey  <tom@tromey.com>

	PR rust/22236:
	* gdb.rust/simple.rs (main): New variable "fslice".
	* gdb.rust/simple.exp: Add slice tests.  Update string tests.

1 files changed, 2 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.rust/simple.rs b/gdb/testsuite/gdb.rust/simple.rs
index 9c154e7..d6d1755 100644
--- a/gdb/testsuite/gdb.rust/simple.rs
+++ b/gdb/testsuite/gdb.rust/simple.rs
@@ -95,6 +95,8 @@ fn main () {
     let g = b"hi bob";
     let h = b'9';
 
+    let fslice = &f[3..];
+
     let i = ["whatever"; 8];
 
     let j = Unit;