[PATCH] Skip tests requiring "alignof (void)" when compiling using clang

[Gary Benson <gbenson@redhat.com>]

Hi all,

Clang fails to compile the generated output of gdb.cp/align.exp with
the following error: invalid application of 'alignof' to an incomplete
type 'void'.  This patch adds preprocessor conditionals to the
generated output, to avoid the offending code, and causes the tests
that require it to be skipped.

Checked on Fedora 31 x86_64, GCC and clang.  Ok to commit?

Cheers,
Gary

--
gdb/testsuite/ChangeLog:

	* gdb.cp/align.exp: Skip tests requiring "alignof (void)"
	when compiling using clang.
---
 gdb/testsuite/ChangeLog        | 5 +++++
 gdb/testsuite/gdb.cp/align.exp | 9 +++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/gdb/testsuite/gdb.cp/align.exp b/gdb/testsuite/gdb.cp/align.exp
index 0905a27..65ffb3b 100644
--- a/gdb/testsuite/gdb.cp/align.exp
+++ b/gdb/testsuite/gdb.cp/align.exp
@@ -80,7 +80,9 @@ puts $outfile {
 
     unsigned a_int3 = alignof (int[3]);
 
+#if !defined(__clang__)
     unsigned a_void = alignof (void);
+#endif
 
     struct base { char c; };
     struct derived : public virtual base { int i; };
@@ -170,5 +172,8 @@ foreach type $typelist {
 
 set expected [get_integer_valueof a_int3 0]
 gdb_test "print alignof(int\[3\])" " = $expected"
-set expected [get_integer_valueof a_void 0]
-gdb_test "print alignof(void)" " = $expected"
+
+if ![test_compiler_info clang*] {
+    set expected [get_integer_valueof a_void 0]
+    gdb_test "print alignof(void)" " = $expected"
+}
-- 
1.8.3.1