Re: [PATCH] Enable gdb.cp/ambiguous.exp with GCC >= 10.1 and clang

[Pedro Alves <pedro@palves.net>]

On 7/27/20 2:09 PM, Gary Benson via Gdb-patches wrote:
> Hi all,
> 
> gdb.cp/ambiguous.exp failed to build using clang with the following
> error:
> 
>  gdb compile failed, /gdbtest/src/gdb/testsuite/gdb.cp/ambiguous.cc:70:36:
>    warning: direct base 'A1' is inaccessible due to ambiguity:
>      class JVA1 -> class KV -> class A1
>      class JVA1 -> class A1 [-Winaccessible-base]
>  class JVA1 : public KV, public LV, public A1 {
>                                    ^~~~~~~~~
> 
> This commit builds this testcase with -Wno-inaccessible-base when
> using clang, to avoid this failure.
> 
> Furthermore, gdb.cp/ambiguous.exp has been disabled when using GCC
> since 1998.  

Curious you reference the year, do you know it because you found the
commit that disabled it?

> This commit enables this testcase when compiling with
> GCC >= 10.1, the first version with -Wno-inaccessible-base.
> 
> Checked on Fedora 31 x86_64, GCC and clang.  Ok to commit?
> 
> Cheers,
> Gary
> 
> --
> gdb/testsuite/ChangeLog:
> 
> 	* gdb.cp/ambiguous.exp: Enable test when compiling with GCC >=
> 	10.1.  Add additional_flags=-Wno-inaccessible-base when compiling
> 	with GCC or clang.
> ---
>  gdb/testsuite/ChangeLog            |  6 ++++++
>  gdb/testsuite/gdb.cp/ambiguous.exp | 17 +++++++++++++++--
>  2 files changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/gdb/testsuite/gdb.cp/ambiguous.exp b/gdb/testsuite/gdb.cp/ambiguous.exp
> index fffe20a..26f96a9 100644
> --- a/gdb/testsuite/gdb.cp/ambiguous.exp
> +++ b/gdb/testsuite/gdb.cp/ambiguous.exp
> @@ -30,12 +30,25 @@ if { [skip_cplus_tests] } { continue }
>  standard_testfile .cc
>  
>  if [get_compiler_info "c++"] {
> +    unsupported "couldn't find a valid c++ compiler"
>      return -1
>  }
>  
> -if { [test_compiler_info gcc-*] } then { continue }
> +# GCCs prior to 10.1 do not support -Wno-inaccessible-base.
> +if { [test_compiler_info {gcc-[0-9]-*}]
> +     || [test_compiler_info {gcc-10-0-*}] } {

Given the first release of GCC 10 is 10.1, do we really
need the second check?

> +    unsupported "compiler does not support -Wno-inaccessible-base"

How about instead of bailing out, use "-Wno-inaccessible-base"
with GCC >= 10, and use "-w" with older GCCs?