On Thu, 2020-11-05 at 11:03 -0500, Marek Polacek via Gcc-patches wrote:
> This PR asks that we add a warning option for an existing (very old)
> warning, so that it can be disabled selectively. clang++ uses
> -Wexceptions for this, so I added this new option rather than using
> e.g. -Wnoexcept.
>
> gcc/c-family/ChangeLog:
>
> PR c++/97675
> * c.opt (Wexceptions): New option.
>
> gcc/cp/ChangeLog:
>
> PR c++/97675
> * except.c (check_handlers_1): Use OPT_Wexceptions for the
> warning. Use inform for the second part of the warning.
>
> gcc/ChangeLog:
>
> PR c++/97675
> * doc/invoke.texi: Document -Wexceptions.
>
> gcc/testsuite/ChangeLog:
>
> PR c++/97675
> * g++.old-deja/g++.eh/catch10.C: Adjust dg-warning.
> * g++.dg/warn/Wexceptions1.C: New test.
> * g++.dg/warn/Wexceptions2.C: New test.
> ---
> gcc/c-family/c.opt | 4 ++++
> gcc/cp/except.c | 9 ++++-----
> gcc/doc/invoke.texi | 8 +++++++-
> gcc/testsuite/g++.dg/warn/Wexceptions1.C | 9 +++++++++
> gcc/testsuite/g++.dg/warn/Wexceptions2.C | 10 ++++++++++
> gcc/testsuite/g++.old-deja/g++.eh/catch10.C | 4 ++--
> 6 files changed, 36 insertions(+), 8 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/warn/Wexceptions1.C
> create mode 100644 gcc/testsuite/g++.dg/warn/Wexceptions2.C
>
> diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
> index 426636be839..9493acb82ff 100644
> --- a/gcc/c-family/c.opt
> +++ b/gcc/c-family/c.opt
> @@ -579,6 +579,10 @@ Werror-implicit-function-declaration
> C ObjC RejectNegative Warning Alias(Werror=, implicit-function-
> declaration)
> This switch is deprecated; use -Werror=implicit-function-declaration
> instead.
>
> +Wexceptions
> +C++ ObjC++ Var(warn_exceptions) Init(1)
> +Warn when an exception handler is shadowed by another handler.
> +
> Wextra
> C ObjC C++ ObjC++ Warning
> ; in common.opt
> diff --git a/gcc/cp/except.c b/gcc/cp/except.c
> index cb1a4105dae..985206f6a64 100644
> --- a/gcc/cp/except.c
> +++ b/gcc/cp/except.c
> @@ -975,11 +975,10 @@ check_handlers_1 (tree master,
> tree_stmt_iterator i)
> tree handler = tsi_stmt (i);
> if (TREE_TYPE (handler) && can_convert_eh (type, TREE_TYPE
> (handler)))
> {
Can you add an auto_diagnostic_group here please.
> - warning_at (EXPR_LOCATION (handler), 0,
> - "exception of type %qT will be caught",
> - TREE_TYPE (handler));
> - warning_at (EXPR_LOCATION (master), 0,
> - " by earlier handler for %qT", type);
> + if (warning_at (EXPR_LOCATION (handler), OPT_Wexceptions,
> + "exception of type %qT will be caught by
> earlier "
> + "handler", TREE_TYPE (handler)))
> + inform (EXPR_LOCATION (master), "for type %qT", type);
> break;
> }
> }
Thanks
Dave
