gdb: print unknown part of flag enum in hex

When we print the "unknown" part of a flag enum, it is printed in
decimal.  I think it would be more useful if it was printed in hex, as
it helps to determine which bits are set more than a decimal value.

gdb/ChangeLog:

	* valprint.c (generic_val_print_enum_1): Print unknown part of
	flag enum in hex.

gdb/testsuite/ChangeLog:

	* gdb.base/printcmds.exp (test_print_enums): Expect hex values
	for "unknown".

gdb/ChangeLog

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 6ea5959..cc47e2d 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,10 @@
 2020-02-18  Simon Marchi  <simon.marchi@efficios.com>
 
+	* valprint.c (generic_val_print_enum_1): Print unknown part of
+	flag enum in hex.
+
+2020-02-18  Simon Marchi  <simon.marchi@efficios.com>
+
 	* dwarf2/read.c (update_enumeration_type_from_children): Allow
 	flag enums to contain duplicate enumerators.
 	* valprint.c (generic_val_print_enum_1): Update comment.

gdb/testsuite/ChangeLog

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 4f63dde..087714b 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,10 @@
 2020-02-18  Simon Marchi  <simon.marchi@efficios.com>
 
+	* gdb.base/printcmds.exp (test_print_enums): Expect hex values
+	for "unknown".
+
+2020-02-18  Simon Marchi  <simon.marchi@efficios.com>
+
 	* gdb.base/printcmds.c (enum flag_enum): Add FE_TWO_LEGACY
 	enumerator.
 

gdb/testsuite/gdb.base/printcmds.exp

diff --git a/gdb/testsuite/gdb.base/printcmds.exp b/gdb/testsuite/gdb.base/printcmds.exp
index 6afb965..d6f5c75 100644
--- a/gdb/testsuite/gdb.base/printcmds.exp
+++ b/gdb/testsuite/gdb.base/printcmds.exp
@@ -743,10 +743,10 @@
     gdb_test "print (enum flag_enum) 0x0" [string_to_regexp " = FE_NONE"]
 
     # Print a flag enum with value 0, where no enumerator has value 0.
-    gdb_test "print flag_enum_without_zero" [string_to_regexp " = (unknown: 0)"]
+    gdb_test "print flag_enum_without_zero" [string_to_regexp " = (unknown: 0x0)"]
 
     # Print a flag enum with unknown bits set.
-    gdb_test "print (enum flag_enum) 0xf1" [string_to_regexp " = (FE_ONE | unknown: 240)"]
+    gdb_test "print (enum flag_enum) 0xf1" [string_to_regexp " = (FE_ONE | unknown: 0xf0)"]
 
     # Test printing an enum not considered a "flag enum" (because one of its
     # enumerators has multiple bits set).

gdb/valprint.c

diff --git a/gdb/valprint.c b/gdb/valprint.c
index 888c9cd..67049e7 100644
--- a/gdb/valprint.c
+++ b/gdb/valprint.c
@@ -660,8 +660,8 @@
 	{
 	  if (!first)
 	    fputs_filtered (" | ", stream);
-	  fputs_filtered ("unknown: ", stream);
-	  print_longest (stream, 'd', 0, val);
+	  fputs_filtered ("unknown: 0x", stream);
+	  print_longest (stream, 'x', 0, val);
 	}
 
       fputs_filtered (")", stream);