ping
https://gcc.gnu.org/pipermail/gcc-patches/2022-June/597560.html
On Thu, 30 Jun 2022 at 17:53, Jonathan Wakely <jwak...@redhat.com> wrote:
>
> Tested powerpc64le-linux, OK for trunk?
>
> -- >8 --
>
> Since C++11 relaxed the requirement for template arguments to have
> external linkage, it's possible to get -Wsubobject-linkage warnings
> without using any anonymous namespaces. This confuses users when they
> get diagnostics that refer to an anonymous namespace that doesn't exist
> in their code.
>
> This changes the diagnostic to say "has internal linkage" for C++11 and
> later, which is accurate whether internal linkage is due to the 'static'
> specifier, or due to the use of anonymous namespaces.
>
> For C++98 template arguments declared with 'static' are ill-formed
> anyway, so the only way this warning can arise is via anonymous
> namespaces. That means the existing wording is accurate for C++98 and so
> we can keep it.
>
> PR c++/86491
>
> gcc/cp/ChangeLog:
>
> * decl2.cc (constrain_class_visibility): Adjust wording of
> -Wsubobject-linkage to account for cases where anonymous
> namespaces aren't used.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/warn/Wsubobject-linkage-3.C: Adjust for new warning.
> * g++.dg/warn/anonymous-namespace-1.C: Use separate dg-warning
> directives for C++98 and everything else.
> * g++.dg/warn/anonymous-namespace-2.C: Likewise.
> * g++.dg/warn/anonymous-namespace-3.C: Likewise.
> ---
> gcc/cp/decl2.cc | 12 ++++++++++--
> gcc/testsuite/g++.dg/warn/Wsubobject-linkage-3.C | 4 ++--
> gcc/testsuite/g++.dg/warn/anonymous-namespace-1.C | 8 ++++++--
> gcc/testsuite/g++.dg/warn/anonymous-namespace-2.C | 9 ++++++---
> gcc/testsuite/g++.dg/warn/anonymous-namespace-3.C | 3 ++-
> 5 files changed, 26 insertions(+), 10 deletions(-)
>
> diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
> index 3737e5f010c..de53678715e 100644
> --- a/gcc/cp/decl2.cc
> +++ b/gcc/cp/decl2.cc
> @@ -3027,7 +3027,11 @@ constrain_class_visibility (tree type)
> %qT has a field %qD whose type depends on the type %qT which has no linkage",
> type, t, nlt);
> }
> - else
> + else if (cxx_dialect > cxx98)
> + warning (OPT_Wsubobject_linkage, "\
> +%qT has a field %qD whose type has internal linkage",
> + type, t);
> + else // In C++98 this can only happen with unnamed namespaces.
> warning (OPT_Wsubobject_linkage, "\
> %qT has a field %qD whose type uses the anonymous namespace",
> type, t);
> @@ -3062,7 +3066,11 @@ constrain_class_visibility (tree type)
> %qT has a base %qT whose type depends on the type %qT which has no linkage",
> type, TREE_TYPE (t), nlt);
> }
> - else
> + else if (cxx_dialect > cxx98)
> + warning (OPT_Wsubobject_linkage, "\
> +%qT has a base %qT whose type has internal linkage",
> + type, TREE_TYPE (t));
> + else // In C++98 this can only happen with unnamed namespaces.
> warning (OPT_Wsubobject_linkage, "\
> %qT has a base %qT whose type uses the anonymous namespace",
> type, TREE_TYPE (t));
> diff --git a/gcc/testsuite/g++.dg/warn/Wsubobject-linkage-3.C
> b/gcc/testsuite/g++.dg/warn/Wsubobject-linkage-3.C
> index 95a04501441..b116fbbb186 100644
> --- a/gcc/testsuite/g++.dg/warn/Wsubobject-linkage-3.C
> +++ b/gcc/testsuite/g++.dg/warn/Wsubobject-linkage-3.C
> @@ -3,7 +3,7 @@
> namespace { struct Foo { }; }
>
> #line 6 "foo.C"
> -struct Bar { Foo foo; }; // { dg-warning "anonymous namespace" }
> +struct Bar { Foo foo; }; // { dg-warning "anonymous namespace|internal
> linkage" }
> // { dg-bogus "no linkage" "" { target *-*-* } .-1 }
> -struct Bar2 : Foo { }; // { dg-warning "anonymous namespace" }
> +struct Bar2 : Foo { }; // { dg-warning "anonymous namespace|internal
> linkage" }
> // { dg-bogus "no linkage" "" { target *-*-* } .-1 }
> diff --git a/gcc/testsuite/g++.dg/warn/anonymous-namespace-1.C
> b/gcc/testsuite/g++.dg/warn/anonymous-namespace-1.C
> index cf193e0cba5..eed3818c5cf 100644
> --- a/gcc/testsuite/g++.dg/warn/anonymous-namespace-1.C
> +++ b/gcc/testsuite/g++.dg/warn/anonymous-namespace-1.C
> @@ -14,5 +14,9 @@ class foobar1
> };
>
> #line 17 "foo.C"
> -class foobar : public bad { }; // { dg-warning "uses the anonymous
> namespace" }
> -class foobar2 { bad b; }; // { dg-warning "uses the anonymous namespace" }
> +class foobar : public bad { };
> +// { dg-warning "has internal linkage" "" { target c++11 } .-1 }
> +// { dg-warning "uses the anonymous namespace" "" { target c++98_only } .-2 }
> +class foobar2 { bad b; };
> +// { dg-warning "has internal linkage" "" { target c++11 } .-1 }
> +// { dg-warning "uses the anonymous namespace" "" { target c++98_only } .-2 }
> diff --git a/gcc/testsuite/g++.dg/warn/anonymous-namespace-2.C
> b/gcc/testsuite/g++.dg/warn/anonymous-namespace-2.C
> index 4048f3959df..f2ca5915278 100644
> --- a/gcc/testsuite/g++.dg/warn/anonymous-namespace-2.C
> +++ b/gcc/testsuite/g++.dg/warn/anonymous-namespace-2.C
> @@ -18,12 +18,15 @@ struct g3 {
> };
>
> #line 21 "foo.C"
> -struct b1 { // { dg-warning "uses the anonymous namespace" }
> +struct b1 { // { dg-warning "has internal linkage" "" { target c++11 } }
> +// { dg-warning "uses the anonymous namespace" "" { target c++98_only } .-1 }
> bad * B;
> };
> -struct b2 { // { dg-warning "uses the anonymous namespace" }
> +struct b2 { // { dg-warning "has internal linkage" "" { target c++11 } }
> +// { dg-warning "uses the anonymous namespace" "" { target c++98_only } .-1 }
> bad * B[1];
> };
> -struct b3 { // { dg-warning "uses the anonymous namespace" }
> +struct b3 { // { dg-warning "has internal linkage" "" { target c++11 } }
> +// { dg-warning "uses the anonymous namespace" "" { target c++98_only } .-1 }
> bad (*B)[1];
> };
> diff --git a/gcc/testsuite/g++.dg/warn/anonymous-namespace-3.C
> b/gcc/testsuite/g++.dg/warn/anonymous-namespace-3.C
> index 8b72abdf5d1..ce5745b25f0 100644
> --- a/gcc/testsuite/g++.dg/warn/anonymous-namespace-3.C
> +++ b/gcc/testsuite/g++.dg/warn/anonymous-namespace-3.C
> @@ -7,7 +7,8 @@
> struct B { std::auto_ptr<A> p; };
>
> #line 10 "foo.C"
> -struct C // { dg-warning "uses the anonymous namespace" }
> +struct C // { dg-warning "has internal linkage" "" { target c++11 } }
> +// { dg-warning "uses the anonymous namespace" "" { target c++98_only } .-1 }
> {
> std::auto_ptr<A> p;
> };
> --
> 2.36.1
>
