[binutils-gdb/gdb-16-branch] Fix crash in DWARF indexer

[Tom Tromey]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=c310e35131a79827daccc316f31fe0a22306a02b

commit c310e35131a79827daccc316f31fe0a22306a02b
Author: Tom Tromey <tromey@adacore.com>
Date:   Mon Jan 6 13:34:47 2025 -0700

    Fix crash in DWARF indexer
    
    Iain pointed out a crash in the DWARF indexer when run on a certain D
    program.  The DWARF in this case has a nameless enum class; this
    causes an assertion failure.
    
    This patch arranges to simply ignore such types.  The fact that an
    enum class is nameless in this case appears to be a compiler bug.
    
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32518
    Approved-By: Tom de Vries <tdevries@suse.de>
    
    (cherry picked from commit 66903f1d66a2648e82250a427a791286e4ed4735)

Diff:
---
 gdb/dwarf2/read.c                          |  6 +++
 gdb/testsuite/gdb.dwarf2/nameless-enum.exp | 62 ++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 86448abc339..096a20cb627 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -16809,6 +16809,12 @@ cooked_indexer::index_dies (cutu_reader *reader,
 	      break;
 
 	    case DW_TAG_enumeration_type:
+	      /* Some versions of gdc could emit an "enum class"
+		 without a name, which is nonsensical.  These are
+		 skipped.  */
+	      if (is_enum_class && this_entry == nullptr)
+		continue;
+
 	      /* We need to recurse even for an anonymous enumeration.
 		 Which scope we record as the parent scope depends on
 		 whether we're reading an "enum class".  If so, we use
diff --git a/gdb/testsuite/gdb.dwarf2/nameless-enum.exp b/gdb/testsuite/gdb.dwarf2/nameless-enum.exp
new file mode 100644
index 00000000000..1610b7cea08
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/nameless-enum.exp
@@ -0,0 +1,62 @@
+# Copyright 2025 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 a nameless "enum class".  This is nonsensical but previously
+# made gdb crash.
+
+load_lib dwarf.exp
+require dwarf2_support
+
+standard_testfile main.c .S
+
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+    global srcfile
+
+    cu {} {
+	DW_TAG_compile_unit {
+	    {DW_AT_language @DW_LANG_D}
+	    {DW_AT_name	$srcfile}
+	    {DW_AT_comp_dir /tmp}
+	} {
+	    declare_labels integer_label
+
+	    integer_label: DW_TAG_base_type {
+		{DW_AT_byte_size 4 DW_FORM_sdata}
+		{DW_AT_encoding	 @DW_ATE_signed}
+		{DW_AT_name	 int}
+	    }
+
+	    DW_TAG_enumeration_type {
+		{DW_AT_type :$integer_label}
+		{DW_AT_enum_class 1 DW_FORM_flag}
+	    } {
+		DW_TAG_enumerator {
+		    {DW_AT_name VALUE}
+		    {DW_AT_const_value 17 DW_FORM_sdata}
+		}
+	    }
+	}
+    }
+}
+
+if {[prepare_for_testing "failed to prepare" ${testfile} \
+	 [list $srcfile $asm_file] {nodebug}]} {
+    return -1
+}
+
+# The bug was a crash, so just do anything here to verify gdb is still
+# alive.
+gdb_test "print 23" " = 23"