[PATCH v2] Skip VLA structure field tests when compiling with clang

[Gary Benson <gbenson@redhat.com>]

Hi Luis,

Luis Machado wrote:
> As a general comment (for this and other patches like this), I think
> the preprocessor blocks intermixed with the test code make it harder
> to follow and update the test.
>
> If clang claims it will never support a particular feature, then
> maybe we should ... separate the bits clang doesn't support and put
> it into a separate test that clang-compiled hosts should skip?

Thanks for the review.  I've made that change, the updated patch is
below.  I checked it on Fedora 31 x86_64, GCC and clang.  Is it ok to
commit?

Cheers
Gary

--
Clang fails to compile gdb.base/vla-datatypes.c with the following
error: fields must have a constant size: 'variable length array in
structure' extension will never be supported.  This patch factors
the affected tests out into a new testcase, vla-struct-fields.{exp,c},
which is skipped when the testcase is compiled using clang,

gdb/testsuite/ChangeLog:

	* gdb.base/vla-datatypes.c (vla_factory): Factor out sections
	defining and using VLA structure fields into...
	* gdb.base/vla-struct-fields.c: New file.
	* gdb.base/vla-datatypes.exp: Factor out VLA structure field
	tests into...
	* gdb.base/vla-struct-fields.exp: New file.
---
 gdb/testsuite/ChangeLog                      |   9 +++
 gdb/testsuite/gdb.base/vla-datatypes.c       |  53 --------------
 gdb/testsuite/gdb.base/vla-datatypes.exp     |  24 -------
 gdb/testsuite/gdb.base/vla-struct-fields.c   | 104 +++++++++++++++++++++++++++
 gdb/testsuite/gdb.base/vla-struct-fields.exp |  67 +++++++++++++++++
 5 files changed, 180 insertions(+), 77 deletions(-)
 create mode 100644 gdb/testsuite/gdb.base/vla-struct-fields.c
 create mode 100644 gdb/testsuite/gdb.base/vla-struct-fields.exp

diff --git a/gdb/testsuite/gdb.base/vla-datatypes.c b/gdb/testsuite/gdb.base/vla-datatypes.c
index 682319f..d8b835a 100644
--- a/gdb/testsuite/gdb.base/vla-datatypes.c
+++ b/gdb/testsuite/gdb.base/vla-datatypes.c
@@ -46,49 +46,6 @@ struct foo
   BAR             bar_vla[n];
   int i;
 
-  struct vla_struct
-  {
-    int something;
-    int vla_field[n];
-  };
-  /* Define a typedef for a VLA structure.  */
-  typedef struct vla_struct vla_struct_typedef;
-  vla_struct_typedef vla_struct_object;
-
-  struct inner_vla_struct
-  {
-    int something;
-    int vla_field[n];
-    int after;
-  } inner_vla_struct_object;
-
-  /* Define a structure which uses a typedef for the VLA field
-     to make sure that GDB creates the proper type for this field,
-     preventing a possible assertion failure (see gdb/21356).  */
-  struct vla_struct_typedef_struct_member
-  {
-    int something;
-    vla_struct_typedef vla_object;
-  } vla_struct_typedef_struct_member_object;
-
-  union vla_union
-  {
-    int vla_field[n];
-  } vla_union_object;
-
-  /* Like vla_struct_typedef_struct_member but a union type.  */
-  union vla_struct_typedef_union_member
-  {
-    int something;
-    vla_struct_typedef vla_object;
-  } vla_struct_typedef_union_member_object;
-
-  vla_struct_object.something = n;
-  inner_vla_struct_object.something = n;
-  inner_vla_struct_object.after = n;
-  vla_struct_typedef_struct_member_object.something = n * 2;
-  vla_struct_typedef_struct_member_object.vla_object.something = n * 3;
-  vla_struct_typedef_union_member_object.vla_object.something = n + 1;
   for (i = 0; i < n; i++)
     {
       int_vla[i] = i*2;
@@ -104,13 +61,6 @@ struct foo
       foo_vla[i].a = i*2;
       bar_vla[i].x = i*2;
       bar_vla[i].y.a = i*2;
-      vla_struct_object.vla_field[i] = i*2;
-      vla_union_object.vla_field[i] = i*2;
-      inner_vla_struct_object.vla_field[i] = i*2;
-      vla_struct_typedef_struct_member_object.vla_object.vla_field[i]
-	= i * 3;
-      vla_struct_typedef_union_member_object.vla_object.vla_field[i]
-	= i * 3 - 1;
     }
 
   size_t int_size        = sizeof(int_vla);     /* vlas_filled */
@@ -124,9 +74,6 @@ struct foo
   size_t uchar_size      = sizeof(unsigned_char_vla);
   size_t foo_size        = sizeof(foo_vla);
   size_t bar_size        = sizeof(bar_vla);
-  size_t vla_struct_object_size = sizeof(vla_struct_object);
-  size_t vla_union_object_size = sizeof(vla_union_object);
-  size_t inner_vla_struct_object_size = sizeof(inner_vla_struct_object);
 
   return;                                 /* break_end_of_vla_factory */
 }
diff --git a/gdb/testsuite/gdb.base/vla-datatypes.exp b/gdb/testsuite/gdb.base/vla-datatypes.exp
index e8d8457..201f051 100644
--- a/gdb/testsuite/gdb.base/vla-datatypes.exp
+++ b/gdb/testsuite/gdb.base/vla-datatypes.exp
@@ -41,14 +41,6 @@ gdb_test "print foo_vla" \
          "\\\{\\\{a = 0\\\}, \\\{a = 2\\\}, \\\{a = 4\\\}, \\\{a = 6\\\}, \\\{a = 8\\\}\\\}"
 gdb_test "print bar_vla" \
          "\\\{\\\{x = 0, y = \\\{a = 0\\\}\\\}, \\\{x = 2, y = \\\{a = 2\\\}\\\}, \\\{x = 4, y = \\\{a = 4\\\}\\\}, \\\{x = 6, y = \\\{a = 6\\\}\\\}, \\\{x = 8, y = \\\{a = 8\\\}\\\}\\\}"
-gdb_test "print vla_struct_object" \
-    "\\\{something = 5, vla_field = \\\{0, 2, 4, 6, 8\\\}\\\}"
-gdb_test "print vla_union_object" \
-    "\\\{vla_field = \\\{0, 2, 4, 6, 8\\\}\\\}"
-gdb_test "print vla_struct_typedef_struct_member_object" \
-    "\\\{something = 10, vla_object = \\\{something = 15, vla_field = \\\{0, 3, 6, 9, 12\\\}\\\}\\\}"
-gdb_test "print vla_struct_typedef_union_member_object" \
-    "\\\{something = 6, vla_object = \\\{something = 6, vla_field = \\\{-1, 2, 5, 8, 11\\\}\\\}\\\}"
 
 # Check whatis of VLA's.
 gdb_test "whatis int_vla" "type = int \\\[5\\\]"
@@ -65,8 +57,6 @@ gdb_test "whatis unsigned_short_vla" \
 gdb_test "whatis unsigned_char_vla" "type = unsigned char \\\[5\\\]"
 gdb_test "whatis foo_vla" "type = struct foo \\\[5\\\]"
 gdb_test "whatis bar_vla" "type = BAR \\\[5\\\]"
-gdb_test "whatis vla_struct_object" "type = vla_struct_typedef"
-gdb_test "whatis vla_union_object" "type = union vla_union"
 
 # Check ptype of VLA's.
 gdb_test "ptype int_vla" "type = int \\\[5\\\]"
@@ -82,10 +72,6 @@ gdb_test "ptype unsigned_char_vla" "type = unsigned char \\\[5\\\]"
 gdb_test "ptype foo_vla" "type = struct foo {\r\n\\s+int a;\r\n} \\\[5\\\]"
 gdb_test "ptype bar_vla" \
          "type = struct bar {\r\n\\s+int x;\r\n\\s+struct foo y;\r\n} \\\[5\\\]"
-gdb_test "ptype vla_struct_object" \
-    "type = struct vla_struct {\r\n\\s+int something;\r\n\\s+int vla_field\\\[5\\\];\r\n}"
-gdb_test "ptype vla_union_object" \
-    "type = union vla_union {\r\n\\s+int vla_field\\\[5\\\];\r\n}"
 
 # Check the size of the VLA's.
 gdb_breakpoint [gdb_get_line_number "break_end_of_vla_factory"]
@@ -109,10 +95,6 @@ gdb_test "print uchar_size == sizeof(unsigned_char_vla)" " = 1" \
          "size of unsigned_char_vla"
 gdb_test "print foo_size == sizeof(foo_vla)" " = 1" "size of foo_vla"
 gdb_test "print bar_size == sizeof(bar_vla)" " = 1" "size of bar_vla"
-gdb_test "print vla_struct_object_size == sizeof(vla_struct_object)" \
-    " = 1" "size of vla_struct_object"
-gdb_test "print vla_union_object_size == sizeof(vla_union_object)" \
-    " = 1" "size of vla_union_object"
 
 # Check side effects for sizeof argument.
 set sizeof_int [get_sizeof "int" 4]
@@ -130,9 +112,3 @@ gdb_test "print int_vla\[0\]" " = 42" \
 gdb_test "whatis ++int_vla\[0\]" "type = int"
 gdb_test "print int_vla\[0\]" " = 42" \
          "print int_vla\[0\] - whatis no side effects"
-
-# Fails due to incorrect debugging information generated by GCC.
-setup_xfail "*-*-*"
-gdb_test \
-    "print inner_vla_struct_object_size == sizeof(inner_vla_struct_object)" \
-    " = 1" "size of inner_vla_struct_object"
diff --git a/gdb/testsuite/gdb.base/vla-struct-fields.c b/gdb/testsuite/gdb.base/vla-struct-fields.c
new file mode 100644
index 0000000..ef236a7
--- /dev/null
+++ b/gdb/testsuite/gdb.base/vla-struct-fields.c
@@ -0,0 +1,104 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2014-2020 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/>.  */
+
+#include <stddef.h>
+#define SIZE 5
+
+struct foo
+{
+  int a;
+};
+
+typedef struct bar
+{
+  int x;
+  struct foo y;
+} BAR;
+
+void
+vla_factory (int n)
+{
+  struct vla_struct
+  {
+    int something;
+    int vla_field[n];
+  };
+  /* Define a typedef for a VLA structure.  */
+  typedef struct vla_struct vla_struct_typedef;
+  vla_struct_typedef vla_struct_object;
+
+  struct inner_vla_struct
+  {
+    int something;
+    int vla_field[n];
+    int after;
+  } inner_vla_struct_object;
+
+  /* Define a structure which uses a typedef for the VLA field
+     to make sure that GDB creates the proper type for this field,
+     preventing a possible assertion failure (see gdb/21356).  */
+  struct vla_struct_typedef_struct_member
+  {
+    int something;
+    vla_struct_typedef vla_object;
+  } vla_struct_typedef_struct_member_object;
+
+  union vla_union
+  {
+    int vla_field[n];
+  } vla_union_object;
+
+  /* Like vla_struct_typedef_struct_member but a union type.  */
+  union vla_struct_typedef_union_member
+  {
+    int something;
+    vla_struct_typedef vla_object;
+  } vla_struct_typedef_union_member_object;
+  int i;
+
+  vla_struct_object.something = n;
+  inner_vla_struct_object.something = n;
+  inner_vla_struct_object.after = n;
+  vla_struct_typedef_struct_member_object.something = n * 2;
+  vla_struct_typedef_struct_member_object.vla_object.something = n * 3;
+  vla_struct_typedef_union_member_object.vla_object.something = n + 1;
+
+  for (i = 0; i < n; i++)
+    {
+      vla_struct_object.vla_field[i] = i*2;
+      vla_union_object.vla_field[i] = i*2;
+      inner_vla_struct_object.vla_field[i] = i*2;
+      vla_struct_typedef_struct_member_object.vla_object.vla_field[i]
+	= i * 3;
+      vla_struct_typedef_union_member_object.vla_object.vla_field[i]
+	= i * 3 - 1;
+    }
+
+  size_t vla_struct_object_size
+    = sizeof(vla_struct_object);          /* vlas_filled */
+  size_t vla_union_object_size = sizeof(vla_union_object);
+  size_t inner_vla_struct_object_size = sizeof(inner_vla_struct_object);
+
+  return;                                 /* break_end_of_vla_factory */
+}
+
+int
+main (void)
+{
+  vla_factory(SIZE);
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.base/vla-struct-fields.exp b/gdb/testsuite/gdb.base/vla-struct-fields.exp
new file mode 100644
index 0000000..150a328
--- /dev/null
+++ b/gdb/testsuite/gdb.base/vla-struct-fields.exp
@@ -0,0 +1,67 @@
+# Copyright 2014-2020 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
+
+# Clang says it will never support variable length arrays in structures.
+if {[test_compiler_info clang*]} {
+    unsupported "compiler does not variable length arrays in structure"
+    return
+}
+
+if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] } {
+    return -1
+}
+
+if ![runto_main] {
+    return -1
+}
+
+gdb_breakpoint [gdb_get_line_number "vlas_filled"]
+gdb_continue_to_breakpoint "vlas_filled"
+
+# Check the values of VLA's.
+gdb_test "print vla_struct_object" \
+    "\\\{something = 5, vla_field = \\\{0, 2, 4, 6, 8\\\}\\\}"
+gdb_test "print vla_union_object" \
+    "\\\{vla_field = \\\{0, 2, 4, 6, 8\\\}\\\}"
+gdb_test "print vla_struct_typedef_struct_member_object" \
+    "\\\{something = 10, vla_object = \\\{something = 15, vla_field = \\\{0, 3, 6, 9, 12\\\}\\\}\\\}"
+gdb_test "print vla_struct_typedef_union_member_object" \
+    "\\\{something = 6, vla_object = \\\{something = 6, vla_field = \\\{-1, 2, 5, 8, 11\\\}\\\}\\\}"
+
+# Check whatis of VLA's.
+gdb_test "whatis vla_struct_object" "type = vla_struct_typedef"
+gdb_test "whatis vla_union_object" "type = union vla_union"
+
+# Check ptype of VLA's.
+gdb_test "ptype vla_struct_object" \
+    "type = struct vla_struct {\r\n\\s+int something;\r\n\\s+int vla_field\\\[5\\\];\r\n}"
+gdb_test "ptype vla_union_object" \
+    "type = union vla_union {\r\n\\s+int vla_field\\\[5\\\];\r\n}"
+
+# Check the size of the VLA's.
+gdb_breakpoint [gdb_get_line_number "break_end_of_vla_factory"]
+gdb_continue_to_breakpoint "break_end_of_vla_factory"
+gdb_test "print vla_struct_object_size == sizeof(vla_struct_object)" \
+    " = 1" "size of vla_struct_object"
+gdb_test "print vla_union_object_size == sizeof(vla_union_object)" \
+    " = 1" "size of vla_union_object"
+
+# Fails due to incorrect debugging information generated by GCC.
+setup_xfail "*-*-*"
+gdb_test \
+    "print inner_vla_struct_object_size == sizeof(inner_vla_struct_object)" \
+    " = 1" "size of inner_vla_struct_object"
-- 
1.8.3.1