[PATCH] Print type name when printing Rust slice

[Tom Tromey]

The recent change to how unsized Rust values are printed included a
small regression from past behavior.  Previously, a slice's type would
be printed, like:

    (gdb) print slice
    $80 = &[i32] [3]

The patch changed this to just

    (gdb) print slice
    $80 = [3]

This patch restores the previous behavior.
---
 gdb/rust-lang.c                    | 11 +++++++++++
 gdb/testsuite/gdb.rust/simple.exp  |  2 +-
 gdb/testsuite/gdb.rust/unsized.exp |  2 +-
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/gdb/rust-lang.c b/gdb/rust-lang.c
index ab537cc9752..d7265f72770 100644
--- a/gdb/rust-lang.c
+++ b/gdb/rust-lang.c
@@ -476,6 +476,17 @@ rust_language::val_print_slice
 	}
     }
 
+  /* Print the slice type here.  This was gdb's historical behavior
+     (from before unsized types were generically handled) and helps
+     make it clear that the user is seeing a slice, not an array.
+     Only arrays must be handled as the other cases are handled by
+     value_print_inner.  */
+  if (type->code () == TYPE_CODE_ARRAY)
+    {
+      type_print (orig_type, "", stream, -1);
+      gdb_printf (stream, " ");
+    }
+
   value_print_inner (val, stream, recurse, options);
 }
 
diff --git a/gdb/testsuite/gdb.rust/simple.exp b/gdb/testsuite/gdb.rust/simple.exp
index 7f5fbad7a3f..1e6fc94400e 100644
--- a/gdb/testsuite/gdb.rust/simple.exp
+++ b/gdb/testsuite/gdb.rust/simple.exp
@@ -317,7 +317,7 @@ proc test_one_slice {svar length base range} {
 	global hex
 
 	# Just accept any array here.
-	set result " = \\\[.*\\\]"
+	set result " = &\\\[.*\\\] \\\[.*\\\]"
 
 	gdb_test "print $svar" $result
 	gdb_test "print &${base}\[${range}\]" $result
diff --git a/gdb/testsuite/gdb.rust/unsized.exp b/gdb/testsuite/gdb.rust/unsized.exp
index fab655790e6..ea5f281cb3d 100644
--- a/gdb/testsuite/gdb.rust/unsized.exp
+++ b/gdb/testsuite/gdb.rust/unsized.exp
@@ -33,6 +33,6 @@ if {![runto ${srcfile}:$line]} {
 gdb_test "ptype us" " = .*V<\\\[u8\\\]>.*"
 
 if {[rust_at_least 1.61]} {
-    gdb_test "print us2" " = \\\[1, 2, 3\\\]"
+    gdb_test "print us2" " = .*u8.* \\\[1, 2, 3\\\]"
     gdb_test "ptype us2" "type = .*"
 }
-- 
2.43.0