[binutils-gdb] Correctly print subrange types in generic_value_print

[binutils-gdb] Correctly print subrange types in generic_value_print

[Tom Tromey]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=79a0742380b5304c734ce6f4359d437325cc7121

commit 79a0742380b5304c734ce6f4359d437325cc7121
Author: Tom Tromey <tromey@adacore.com>
Date:   Thu Mar 10 09:23:45 2022 -0700

    Correctly print subrange types in generic_value_print
    
    I noticed that generic_value_print assumes that a subrange type is
    always a subrange of an integer type.  However, this isn't necessarily
    the case.  In Ada, for example, one has subranges of character and
    enumeration types.
    
    This code isn't often exercised, I think, because languages with real
    subrange types tend to implement their own printers.  However, it
    still seemed worth fixing.

Diff:
---
 gdb/testsuite/gdb.dwarf2/subrange-enum.exp | 78 ++++++++++++++++++++++++++++++
 gdb/valprint.c                             |  9 +++-
 2 files changed, 86 insertions(+), 1 deletion(-)

diff --git a/gdb/testsuite/gdb.dwarf2/subrange-enum.exp b/gdb/testsuite/gdb.dwarf2/subrange-enum.exp
new file mode 100644
index 00000000000..b9f7cb68233
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/subrange-enum.exp
@@ -0,0 +1,78 @@
+# Copyright 2022 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Test generic printing of subrange values.
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    return 0
+}
+
+standard_testfile main.c -dw.S
+
+# Make some DWARF for the test.
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+    cu {} {
+	compile_unit {{language @DW_LANG_C}} {
+	    declare_labels integer_label enum_label subrange_label
+
+            integer_label: DW_TAG_base_type {
+                {DW_AT_byte_size 4 DW_FORM_sdata}
+                {DW_AT_encoding  @DW_ATE_signed}
+                {DW_AT_name      integer}
+            }
+
+	    enum_label: DW_TAG_enumeration_type {
+		{DW_AT_name E}
+		{DW_AT_type :$integer_label}
+	    } {
+		DW_TAG_enumerator {
+		    {DW_AT_name ONE}
+		    {DW_AT_const_value 1 DW_FORM_sdata}
+		}
+		DW_TAG_enumerator {
+		    {DW_AT_name TWO}
+		    {DW_AT_const_value 2 DW_FORM_sdata}
+		}
+		DW_TAG_enumerator {
+		    {DW_AT_name THREE}
+		    {DW_AT_const_value 3 DW_FORM_sdata}
+		}
+	    }
+
+	    subrange_label: DW_TAG_subrange_type {
+		{lower_bound 1 DW_FORM_sdata}
+		{upper_bound 2 DW_FORM_sdata}
+		{type :$enum_label}
+	    }
+
+	    DW_TAG_variable {
+		{name rangeval}
+		{type :$subrange_label}
+		{const_value 2 DW_FORM_udata}
+	    }
+	}
+    }
+}
+
+if { [prepare_for_testing "failed to prepare" ${testfile} \
+	  [list $srcfile $asm_file] {nodebug}] } {
+    return -1
+}
+
+gdb_test "print rangeval" " = TWO"
diff --git a/gdb/valprint.c b/gdb/valprint.c
index d6ec64845f4..c2ffe6224bf 100644
--- a/gdb/valprint.c
+++ b/gdb/valprint.c
@@ -888,6 +888,14 @@ generic_value_print (struct value *val, struct ui_file *stream, int recurse,
   if (is_fixed_point_type (type))
     type = type->fixed_point_type_base_type ();
 
+  /* Widen a subrange to its target type, then use that type's
+     printer.  */
+  while (type->code () == TYPE_CODE_RANGE)
+    {
+      type = check_typedef (TYPE_TARGET_TYPE (type));
+      val = value_cast (type, val);
+    }
+
   switch (type->code ())
     {
     case TYPE_CODE_ARRAY:
@@ -936,7 +944,6 @@ generic_value_print (struct value *val, struct ui_file *stream, int recurse,
       generic_value_print_bool (val, stream, options, decorations);
       break;
 
-    case TYPE_CODE_RANGE:
     case TYPE_CODE_INT:
       generic_value_print_int (val, stream, options);
       break;