[PATCH] Fix bug with character enumeration literal

[Tom Tromey <tromey at adacore dot com>]

gnat encodes character enumeration literals using a few different
schemes.  The gnat compiler documented the "QU" and "QW" encodings,
but failed to document that a simpler encoding was used for certain
characters.

This patch updates gdb to handle this simple Q encoding.  Note that
wide character literals are still not handled.

gdb/ChangeLog
2019-08-07  Tom Tromey  <tromey@adacore.com>

	* ada-exp.y (convert_char_literal): Handle "Q%c" encoding.
	* ada-lang.c (ada_enum_name): Likewise.

gdb/testsuite/ChangeLog
2019-08-07  Tom Tromey  <tromey@adacore.com>

	* gdb.ada/char_enum.exp: Add regression tests.
	* gdb.ada/char_enum/foo.adb (Char_Enum_Type): Use '_'
	and '0'.
	(Char, Gchar): Update.
	* gdb.ada/char_enum/pck.ads (Global_Enum_Type): Use '+'.
---
 gdb/ChangeLog                           | 5 +++++
 gdb/ada-exp.y                           | 5 ++++-
 gdb/ada-lang.c                          | 8 ++++++++
 gdb/testsuite/ChangeLog                 | 8 ++++++++
 gdb/testsuite/gdb.ada/char_enum.exp     | 6 ++++++
 gdb/testsuite/gdb.ada/char_enum/foo.adb | 6 +++---
 gdb/testsuite/gdb.ada/char_enum/pck.ads | 2 +-
 7 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/gdb/ada-exp.y b/gdb/ada-exp.y
index f36aabaf150..c8a7b9c9c75 100644
--- a/gdb/ada-exp.y
+++ b/gdb/ada-exp.y
@@ -1390,7 +1390,10 @@ convert_char_literal (struct type *type, LONGEST val)
   if (TYPE_CODE (type) != TYPE_CODE_ENUM)
     return val;
 
-  xsnprintf (name, sizeof (name), "QU%02x", (int) val);
+  if ((val >= 'a' && val <= 'z') || (val >= '0' && val <= '9'))
+    xsnprintf (name, sizeof (name), "Q%c", (int) val);
+  else
+    xsnprintf (name, sizeof (name), "QU%02x", (int) val);
   size_t len = strlen (name);
   for (f = 0; f < TYPE_NFIELDS (type); f += 1)
     {
diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index 21a8e92462f..609f2d43919 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -9439,6 +9439,14 @@ ada_enum_name (const char *name)
           if (sscanf (name + 2, "%x", &v) != 1)
             return name;
         }
+      else if (((name[1] >= '0' && name[1] <= '9')
+		|| (name[1] >= 'a' && name[1] <= 'z'))
+	       && name[2] == '\0')
+	{
+	  GROW_VECT (result, result_len, 4);
+	  xsnprintf (result, result_len, "'%c'", name[1]);
+	  return result;
+	}
       else
         return name;
 
diff --git a/gdb/testsuite/gdb.ada/char_enum.exp b/gdb/testsuite/gdb.ada/char_enum.exp
index c37d696f66d..1c814aa97f4 100644
--- a/gdb/testsuite/gdb.ada/char_enum.exp
+++ b/gdb/testsuite/gdb.ada/char_enum.exp
@@ -26,5 +26,11 @@ clean_restart ${testfile}
 set bp_location [gdb_get_line_number "STOP" ${testdir}/foo.adb]
 runto "foo.adb:$bp_location"
 
+gdb_test "ptype Char_Enum_Type" "type = \\('A', 'B', 'C', '_', '0'\\)"
 gdb_test "print Char_Enum_Type'('B')" "= 1 'B'"
+gdb_test "print Char_Enum_Type'('_')" "= 3 '_'"
+gdb_test "print Char_Enum_Type'('0')" "= 4 '0'"
+gdb_test "ptype pck.Global_Enum_Type" "type = \\('x', 'Y', '\\+'\\)"
+gdb_test "print pck.Global_Enum_Type'('x')" "= 0 'x'"
 gdb_test "print pck.Global_Enum_Type'('Y')" "= 1 'Y'"
+gdb_test "print pck.Global_Enum_Type'('+')" "= 2 '\\+'"
diff --git a/gdb/testsuite/gdb.ada/char_enum/foo.adb b/gdb/testsuite/gdb.ada/char_enum/foo.adb
index cf7fb7d3399..6ae1ef61ae8 100644
--- a/gdb/testsuite/gdb.ada/char_enum/foo.adb
+++ b/gdb/testsuite/gdb.ada/char_enum/foo.adb
@@ -16,9 +16,9 @@
 with Pck; use Pck;
 
 procedure Foo is
-   type Char_Enum_Type is ('A', 'B', 'C', 'D', 'E');
-   Char : Char_Enum_Type := 'D';
-   Gchar : Global_Enum_Type := 'Z';
+   type Char_Enum_Type is ('A', 'B', 'C', '_', '0');
+   Char : Char_Enum_Type := '_';
+   Gchar : Global_Enum_Type := '+';
 begin
    Do_Nothing (Char'Address);  -- STOP
 end Foo;
diff --git a/gdb/testsuite/gdb.ada/char_enum/pck.ads b/gdb/testsuite/gdb.ada/char_enum/pck.ads
index f952e1c31c1..d3e7423646b 100644
--- a/gdb/testsuite/gdb.ada/char_enum/pck.ads
+++ b/gdb/testsuite/gdb.ada/char_enum/pck.ads
@@ -16,7 +16,7 @@
 with System;
 
 package Pck is
-   type Global_Enum_Type is ('X', 'Y', 'Z');
+   type Global_Enum_Type is ('x', 'Y', '+');
    procedure Do_Nothing (A : System.Address);
 end Pck;
 
-- 
2.20.1