Re: [PATCH] gdb/testsuite: ISO C++17 does not allow register storage class specifier.

[Simon Marchi <simark@simark.ca>]

On 2020-08-22 8:19 a.m., Mark Wielaard wrote:
> g++ enables -Wregister when defaulting to C++17. Disable it for those
> tests that explicitly use register.
> 
> gdb/testsuite/ChangeLog:
> 
> 	* gdb.cp/classes.exp (prepare_for_testing): Add
> 	additional_flags=-Wno-register.
> 	* gdb.cp/inherit.exp (prepare_for_testing): Likewise.
> 	* gdb.cp/misc.exp (prepare_for_testing): Likewise.
> ---
>  gdb/testsuite/ChangeLog          | 7 +++++++
>  gdb/testsuite/gdb.cp/classes.exp | 2 +-
>  gdb/testsuite/gdb.cp/inherit.exp | 2 +-
>  gdb/testsuite/gdb.cp/misc.exp    | 2 +-
>  4 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
> index 7976dd76306..c55c9a71415 100644
> --- a/gdb/testsuite/ChangeLog
> +++ b/gdb/testsuite/ChangeLog
> @@ -1,3 +1,10 @@
> +2020-08-22  Mark Wielaard  <mark@klomp.org>
> +
> +	* gdb.cp/classes.exp (prepare_for_testing): Add
> +	additional_flags=-Wno-register.
> +	* gdb.cp/inherit.exp (prepare_for_testing): Likewise.
> +	* gdb.cp/misc.exp (prepare_for_testing): Likewise.
> +
>  2020-08-20  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>
>  
>  	* gdb.base/print-file-var.exp: Fix typo "breapoint".
> diff --git a/gdb/testsuite/gdb.cp/classes.exp b/gdb/testsuite/gdb.cp/classes.exp
> index 4a2287a8704..89e64c47cf9 100644
> --- a/gdb/testsuite/gdb.cp/classes.exp
> +++ b/gdb/testsuite/gdb.cp/classes.exp
> @@ -25,7 +25,7 @@ load_lib "cp-support.exp"
>  standard_testfile .cc
>  
>  if {[prepare_for_testing "failed to prepare" $testfile $srcfile \
> -	 {debug c++ additional_flags=-Wno-deprecated-register}]} {
> +	{debug c++ additional_flags=-Wno-deprecated-register additional_flags=-Wno-register}]} {
>      return -1
>  }

The register keyword in this test is used here:

  629   /* We don't call any methods for v, so gcc version cygnus-2.3.3-930220
  630      might put this variable in a register.  This is a lose, though, because
  631      it means that GDB can't call any methods for that variable.  */
  632   register small v;

Can we first check if we can simply remove the register keyword from the test?

I don't understand the comment above: do we want v to be in a register or not?  It sounds
like we don't, we want it to be in memory so we can call a method on it, from GDB.  So why
use the register keyword?

>  
> diff --git a/gdb/testsuite/gdb.cp/inherit.exp b/gdb/testsuite/gdb.cp/inherit.exp
> index 2d4635c96ad..677d9ee5476 100644
> --- a/gdb/testsuite/gdb.cp/inherit.exp
> +++ b/gdb/testsuite/gdb.cp/inherit.exp
> @@ -27,7 +27,7 @@ load_lib "cp-support.exp"
>  standard_testfile misc.cc
>  
>  if {[prepare_for_testing "failed to prepare" $testfile $srcfile \
> -	 {debug c++ additional_flags=-Wno-deprecated-register}]} {
> +	{debug c++ additional_flags=-Wno-deprecated-register additional_flags=-Wno-register}]} {
>      return -1
>  }
>  
> diff --git a/gdb/testsuite/gdb.cp/misc.exp b/gdb/testsuite/gdb.cp/misc.exp
> index 61034bf8088..94acbd0b493 100644
> --- a/gdb/testsuite/gdb.cp/misc.exp
> +++ b/gdb/testsuite/gdb.cp/misc.exp
> @@ -20,7 +20,7 @@ if { [skip_cplus_tests] } { continue }
>  standard_testfile .cc
>  
>  if {[prepare_for_testing "failed to prepare" $testfile $srcfile \
> -	 {debug c++ additional_flags=-Wno-deprecated-register}]} {
> +	{debug c++ additional_flags=-Wno-deprecated-register additional_flags=-Wno-register}]} {
>      return -1
>  }

These last two tests use misc.cc, from which classes.cc was copied.  So can we first check if it
would make sense to just drop the register keyword?

Simon