[FYI v2] Handle TYPE_CODE_PTR when printing Rust types

[FYI v2] Handle TYPE_CODE_PTR when printing Rust types

[Tom Tromey]

This changes the Rust type printers to handle TYPE_CODE_PTR.  The
current approach is not ideal, because currently the code can't
distinguish between mut and const, or between pointers and references.
(These are debuginfo deficiencies, for which there are rustc bugs on
file.)

Meanwhile, this at least clears up the case seen in PR rust/23625.

Tested on x86-64 Fedora 28.  The nightly compiler gives the best
results, but I regression-tested with stable and beta as well.

gdb/ChangeLog
2018-11-16  Tom Tromey  <tom@tromey.com>

	PR rust/23625:
	* rust-lang.c (rust_internal_print_type): Handle TYPE_CODE_PTR.

gdb/testsuite/ChangeLog
2018-11-19  Tom Tromey  <tom@tromey.com>

	PR rust/23625:
	* gdb.rust/simple.exp: Add ptype test.  Update expected output.
	* gdb.rust/expr.exp: Update expected output.  Change one test.
---
 gdb/ChangeLog                     |  5 +++++
 gdb/rust-lang.c                   | 14 ++++++++++++++
 gdb/testsuite/ChangeLog           |  6 ++++++
 gdb/testsuite/gdb.rust/expr.exp   |  4 ++--
 gdb/testsuite/gdb.rust/simple.exp | 13 +++++++------
 5 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 436446c9f0b..3939d235cfc 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2018-11-16  Tom Tromey  <tom@tromey.com>
+
+	PR rust/23625:
+	* rust-lang.c (rust_internal_print_type): Handle TYPE_CODE_PTR.
+
 2018-11-19  Simon Marchi  <simon.marchi@ericsson.com>
 
 	* infrun.c (displaced_step_inferior_states): Change type to
diff --git a/gdb/rust-lang.c b/gdb/rust-lang.c
index 152413a612f..0a327ee6195 100644
--- a/gdb/rust-lang.c
+++ b/gdb/rust-lang.c
@@ -918,6 +918,20 @@ rust_internal_print_type (struct type *type, const char *varstring,
       }
       break;
 
+    case TYPE_CODE_PTR:
+      {
+	if (TYPE_NAME (type) != nullptr)
+	  fputs_filtered (TYPE_NAME (type), stream);
+	else
+	  {
+	    /* We currently can't distinguish between pointers and
+	       references.  */
+	    fputs_filtered ("*mut ", stream);
+	    type_print (TYPE_TARGET_TYPE (type), "", stream, 0);
+	  }
+      }
+      break;
+
     default:
     c_printer:
       c_print_type (type, varstring, stream, show, level, flags);
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index e7693a07f54..daa283994c2 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2018-11-19  Tom Tromey  <tom@tromey.com>
+
+	PR rust/23625:
+	* gdb.rust/simple.exp: Add ptype test.  Update expected output.
+	* gdb.rust/expr.exp: Update expected output.  Change one test.
+
 2018-11-19  Tom Tromey  <tom@tromey.com>
 
 	* gdb.rust/simple.rs: Don't initialize empty_enum_value.
diff --git a/gdb/testsuite/gdb.rust/expr.exp b/gdb/testsuite/gdb.rust/expr.exp
index 22e6b49b542..ec230c1a1a8 100644
--- a/gdb/testsuite/gdb.rust/expr.exp
+++ b/gdb/testsuite/gdb.rust/expr.exp
@@ -134,8 +134,8 @@ gdb_test "ptype \[23usize; 4\]" " = \\\[usize; 4\\\]"
 gdb_test "print \[mut 23usize; 4\]" " = \\\[23, 23, 23, 23\\\]"
 
 # Test lexer corner cases.
-gdb_test "print 0x0 as *const ()" " = \\\(\\\(\\\) \\*\\\) 0x0"
-gdb_test "print 0x0 as fn(i64) -> ()" " = \\\(\\\(\\\) \\\(\\*\\\)\\\(i64\\\)\\\) 0x0"
+gdb_test "print 0x0 as *mut ()" " = \\\(\\*mut \\\(\\\)\\\) 0x0"
+gdb_test "print 0x0 as fn(i64) -> ()" " = \\\(\\*mut fn \\\(i64\\\) -> \\\(\\\)\\\) 0x0"
 gdb_test "print r#" "syntax error in expression, near `#'\\."
 
 gdb_test "printf \"%d %d\\n\", 23+1, 23-1" "24 22"
diff --git a/gdb/testsuite/gdb.rust/simple.exp b/gdb/testsuite/gdb.rust/simple.exp
index 956a6ca6fee..f02ff676db6 100644
--- a/gdb/testsuite/gdb.rust/simple.exp
+++ b/gdb/testsuite/gdb.rust/simple.exp
@@ -54,6 +54,7 @@ gdb_test "print *&c" " = 0"
 gdb_test "print *(&c as &i32)" " = 0"
 gdb_test "print *(&c as *const i32)" " = 0"
 gdb_test "print *(&c as *mut i32)" " = 0"
+gdb_test "ptype &c as *mut i32" "\\*mut i32"
 
 gdb_test "print/c f\[0\]" " = 104 'h'"
 
@@ -68,8 +69,8 @@ gdb_test "print f" " = \"hi bob\""
 gdb_test "print fslice" " = \"bob\""
 gdb_test "print &f\[3..\]" " = \"bob\""
 
-gdb_test "print g" " = \\(u8 \\(\\*\\)\\\[6\\\]\\) $hex b\"hi bob\""
-gdb_test "ptype g" " = u8 \\(\\*\\)\\\[6\\\]"
+gdb_test "print g" " = \\(\\*mut \\\[u8; 6\\\]\\) $hex b\"hi bob\""
+gdb_test "ptype g" " = \\*mut \\\[u8; 6\\\]"
 
 gdb_test "print v" " = simple::Something::Three"
 gdb_test_sequence "ptype v" "" {
@@ -91,19 +92,19 @@ gdb_test "print slice as &\[i32\]\[0\]" " = 3"
 
 gdb_test_sequence "ptype slice" "" {
     " = struct &\\\[i32\\\] \\{"
-    "  data_ptr: i32 \\*,"
+    "  data_ptr: \\*mut i32,"
     "  length: usize,"
     "\\}"
 }
 gdb_test_sequence "ptype &slice\[..\]" "" {
     " = struct &\\\[i32\\\] \\{"
-    "  data_ptr: i32 \\*,"
+    "  data_ptr: \\*mut i32,"
     "  length: usize,"
     "\\}"
 }
 gdb_test_sequence "ptype &b\[..\]" "" {
     " = struct &\\\[\\*gdb\\*\\\] \\{"
-    "  data_ptr: i32 \\*,"
+    "  data_ptr: \\*mut i32,"
     "  length: usize,"
     "\\}"
 }
@@ -281,7 +282,7 @@ gdb_test "print 23..97.0" "Range expression with different types"
 gdb_test "print (*parametrized.next.val)" \
     " = simple::ParametrizedStruct<i32> {next: simple::ParametrizedEnum<\[a-z:\]*Box<simple::ParametrizedStruct<i32>>>::Empty, value: 1}"
 gdb_test "print parametrized.next.val" \
-    " = \\(simple::ParametrizedStruct<i32> \\*\\) $hex"
+    " = \\(\\*mut simple::ParametrizedStruct<i32>\\) $hex"
 gdb_test "print parametrized" \
     " = simple::ParametrizedStruct<i32> \\{next: simple::ParametrizedEnum<\[a-z:\]*Box<simple::ParametrizedStruct<i32>>>::Val\\{val: $hex\\}, value: 0\\}"
 
-- 
2.17.2