Fix 7.8 regression: resolve_dynamic_struct: Assertion `TYPE_NFIELDS (type) > 0' (PR 17642)

https://sourceware.org/bugzilla/show_bug.cgi?id=17642

Regression since:
commit 012370f6818657a816df1463ee71ca4e4ee40b33
Author: Tom Tromey <tromey@redhat.com>
Date:   Thu May 8 11:26:44 2014 -0600
    handle VLA in a struct or union

Bugreport:
Regression with gdb scripts for Linux kernel
https://sourceware.org/ml/gdb/2014-08/msg00127.html

That big change after "else" is just reindentation.

gdb/ChangeLog
2014-12-15  Jan Kratochvil  <jan.kratochvil@redhat.com>

	PR symtab/17642
	* gdbtypes.c (resolve_dynamic_type_internal): Apply check_typedef to
	TYPE if not TYPE_CODE_TYPEDEF.

gdb/testsuite/ChangeLog
2014-12-15  Jan Kratochvil  <jan.kratochvil@redhat.com>

	PR symtab/17642
	* gdb.base/vla-stub-define.c: New file.
	* gdb.base/vla-stub.c: New file.
	* gdb.base/vla-stub.exp: New file.

6 files changed, 126 insertions, 24 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 96b42a4fc78..5a2a3a582b5 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,11 @@
 2014-12-15  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
+	PR symtab/17642
+	* gdbtypes.c (resolve_dynamic_type_internal): Apply check_typedef to
+	TYPE if not TYPE_CODE_TYPEDEF.
+
+2014-12-15  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
 	* gdbtypes.c (resolve_dynamic_type_internal): Reindent the code.
 
 2014-10-29  Joel Brobecker  <brobecker@adacore.com>
diff --git a/gdb/gdbtypes.c b/gdb/gdbtypes.c
index 50b0c269669..1a9e2e6afc7 100644
--- a/gdb/gdbtypes.c
+++ b/gdb/gdbtypes.c
@@ -1850,41 +1850,47 @@ resolve_dynamic_type_internal (struct type *type, CORE_ADDR addr,
   if (!is_dynamic_type_internal (real_type, top_level))
     return type;
 
-  switch (TYPE_CODE (type))
+  if (TYPE_CODE (type) == TYPE_CODE_TYPEDEF)
     {
-    case TYPE_CODE_TYPEDEF:
       resolved_type = copy_type (type);
       TYPE_TARGET_TYPE (resolved_type)
 	= resolve_dynamic_type_internal (TYPE_TARGET_TYPE (type), addr,
 					 top_level);
-      break;
+    }
+  else 
+    {
+      /* Before trying to resolve TYPE, make sure it is not a stub.  */
+      type = real_type;
 
-    case TYPE_CODE_REF:
-      {
-	CORE_ADDR target_addr = read_memory_typed_address (addr, type);
+      switch (TYPE_CODE (type))
+	{
+	case TYPE_CODE_REF:
+	  {
+	    CORE_ADDR target_addr = read_memory_typed_address (addr, type);
 
-	resolved_type = copy_type (type);
-	TYPE_TARGET_TYPE (resolved_type)
-	  = resolve_dynamic_type_internal (TYPE_TARGET_TYPE (type),
-					   target_addr, top_level);
-	break;
-      }
+	    resolved_type = copy_type (type);
+	    TYPE_TARGET_TYPE (resolved_type)
+	      = resolve_dynamic_type_internal (TYPE_TARGET_TYPE (type),
+					       target_addr, top_level);
+	    break;
+	  }
 
-    case TYPE_CODE_ARRAY:
-      resolved_type = resolve_dynamic_array (type);
-      break;
+	case TYPE_CODE_ARRAY:
+	  resolved_type = resolve_dynamic_array (type);
+	  break;
 
-    case TYPE_CODE_RANGE:
-      resolved_type = resolve_dynamic_range (type);
-      break;
+	case TYPE_CODE_RANGE:
+	  resolved_type = resolve_dynamic_range (type);
+	  break;
 
-    case TYPE_CODE_UNION:
-      resolved_type = resolve_dynamic_union (type, addr);
-      break;
+	case TYPE_CODE_UNION:
+	  resolved_type = resolve_dynamic_union (type, addr);
+	  break;
 
-    case TYPE_CODE_STRUCT:
-      resolved_type = resolve_dynamic_struct (type, addr);
-      break;
+	case TYPE_CODE_STRUCT:
+	  resolved_type = resolve_dynamic_struct (type, addr);
+	  break;
+	}
     }
 
   return resolved_type;
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index ab45b909fd0..b96bccd82ce 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2014-12-15  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	PR symtab/17642
+	* gdb.base/vla-stub-define.c: New file.
+	* gdb.base/vla-stub.c: New file.
+	* gdb.base/vla-stub.exp: New file.
+
 2014-10-29  Pedro Alves  <palves@redhat.com>
 
 	PR gdb/17408
diff --git a/gdb/testsuite/gdb.base/vla-stub-define.c b/gdb/testsuite/gdb.base/vla-stub-define.c
new file mode 100644
index 00000000000..7445a4fd1f7
--- /dev/null
+++ b/gdb/testsuite/gdb.base/vla-stub-define.c
@@ -0,0 +1,21 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2014 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/>.  */
+
+struct dynamic_struct
+{
+  int dynamic_field[0];
+} use_dynamic_struct;
diff --git a/gdb/testsuite/gdb.base/vla-stub.c b/gdb/testsuite/gdb.base/vla-stub.c
new file mode 100644
index 00000000000..b7ccf041e90
--- /dev/null
+++ b/gdb/testsuite/gdb.base/vla-stub.c
@@ -0,0 +1,37 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2014 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/>.  */
+
+struct dynamic_struct;
+typedef struct dynamic_struct dynamic_struct_t;
+
+struct static_struct
+{
+  int field;
+};
+typedef struct static_struct static_struct_t;
+
+struct local_struct
+{
+  static_struct_t here;
+  dynamic_struct_t *ptr;
+} local_struct;
+
+int
+main (void)
+{
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.base/vla-stub.exp b/gdb/testsuite/gdb.base/vla-stub.exp
new file mode 100644
index 00000000000..f8c9a913070
--- /dev/null
+++ b/gdb/testsuite/gdb.base/vla-stub.exp
@@ -0,0 +1,25 @@
+# Copyright 2014 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/>.
+
+standard_testfile .c vla-stub-define.c
+if { [prepare_for_testing "failed to prepare for vla-stub.exp" \
+      ${testfile} [list ${srcfile} ${srcfile2}]] } {
+    return -1
+}
+
+gdb_test "p *local_struct.ptr" { = {dynamic_field = 0x0}}
+
+gdb_test "whatis local_struct.here" "type = static_struct_t"
+gdb_test "whatis *local_struct.ptr" "type = dynamic_struct_t"