On 10/12/19 2:10 PM, Bernd Edlinger wrote:
On 10/11/19 6:31 PM, Jason Merrill wrote:
On 10/10/19 2:06 PM, Bernd Edlinger wrote:
On 10/10/19 7:49 PM, Jason Merrill wrote:
On 10/10/19 10:42 AM, Bernd Edlinger wrote:
Hi,
this fixes a crash when -Wshadow=compatible-local is
enabled in the testcase g++.dg/parse/crash68.C
Why does that flag cause this crash?
gcc/cp/name-lookup.c:
if (warn_shadow)
warning_code = OPT_Wshadow;
else if (warn_shadow_local)
warning_code = OPT_Wshadow_local;
else if (warn_shadow_compatible_local
&& (same_type_p (TREE_TYPE (old), TREE_TYPE (decl))
|| (!dependent_type_p (TREE_TYPE (decl))
&& !dependent_type_p (TREE_TYPE (old))
/* If the new decl uses auto, we don't yet know
its type (the old type cannot be using auto
at this point, without also being
dependent). This is an indication we're
(now) doing the shadow checking too
early. */
&& !type_uses_auto (TREE_TYPE (decl))
&& can_convert (TREE_TYPE (old), TREE_TYPE (decl),
tf_none))))
warning_code = OPT_Wshadow_compatible_local;
if -Wshadow=compatible-local is used, the can_convert function crashes
in instantiate_class_template_1.
Right, checking can_convert is problematic here, as it can cause template
instantiations that change the semantics of the program. Or, in this case,
crash.
So I try to make C++ behave more consistently with the code in c-decl.c,
thus dependent on warn_shadow but not on warn_shadow_local and/or
warn_shadow_compatible_local:
if (warn_shadow)
warning_code = OPT_Wshadow;
else if (comptypes (TREE_TYPE (old_decl), TREE_TYPE (new_decl)))
warning_code = OPT_Wshadow_compatible_local;
else
warning_code = OPT_Wshadow_local;
warned = warning_at (DECL_SOURCE_LOCATION (new_decl), warning_code,
"declaration of %qD shadows a parameter",
new_decl);
I cannot remove the if (warn_shadow) since this breaks gcc.dg/pr48062.c
which uses:
#pragma GCC diagnostic ignored "-Wshadow"
to disable a -Wshadow=compatible-local warning, but while -Wno-shadow on the
command line disables also dependent warnings the pragma does not (always) do
that.
So instead I'd like to adjust the doc of -Wshadow to reflect the implementation
and remove the if(warn_shadow_local) to have C and C++ behave identical and
hopefully now in sync with the doc.
Bootstrapped and reg-tested on x86_64-pc-linux-gnu.
Is it OK for trunk?
OK, thanks.
Jason
