[PATCH] MS compatibility - explicit specializations can be declared in any namespace

[David Blaikie]

Test case? Also I think we're trying to avoid implementing every random
extension from msvc, preferring to update choose where the number of
instances of code relying on the extension is small (& not in a platform
header) - do you have a particular case where this shows up a lot (such
that it's a substaintial burden to update the code to be conforming)?

I might be wrong about this, so others may come in to correct me, that's
just my vague understanding
On Mar 12, 2015 2:07 AM, "Alexey Frolov" <alexfrolov1878 at yandex.ru> wrote:

> Hi rsmith,
>
> MS compiler emits no errors in case of explicit specializations outside
> declaration enclosing namespaces, even when language extensions are
> disabled.
> The patch is to suppress errors and emit extension warnings if explicit
> specializations are not declared in the corresponding namespaces.
>
> This fixes PR13738.
>
> REPOSITORY
>   rL LLVM
>
> http://reviews.llvm.org/D8283
>
> Files:
>   llvm/tools/clang/include/clang/Basic/DiagnosticSemaKinds.td
>   llvm/tools/clang/lib/Sema/SemaTemplate.cpp
>   llvm/tools/clang/test/SemaTemplate/ext_ms_template_spec.cpp
>
> Index: llvm/tools/clang/test/SemaTemplate/ext_ms_template_spec.cpp
> ===================================================================
> --- llvm/tools/clang/test/SemaTemplate/ext_ms_template_spec.cpp
> +++ llvm/tools/clang/test/SemaTemplate/ext_ms_template_spec.cpp
> @@ -0,0 +1,33 @@
> +// RUN: %clang_cc1 -fsyntax-only -fms-compatibility -std=c++11 -verify %s
> +
> +namespace A {
> +
> +template <class T>
> +class ClassTemplate; // expected-note {{explicitly specialized
> declaration is here}}
> +
> +template <class T1, class T2>
> +class ClassTemplatePartial; // expected-note {{explicitly specialized
> declaration is here}}
> +
> +template <typename T> struct X {
> +  struct MemberClass; // expected-note {{explicitly specialized
> declaration is here}}
> +  enum MemberEnumeration; // expected-note {{explicitly specialized
> declaration is here}}
> +};
> +
> +}
> +
> +namespace B {
> +
> +template <>
> +class A::ClassTemplate<int>; // expected-warning {{class template
> specialization of 'ClassTemplate' outside namespace enclosing 'A' is a
> Microsoft extension}}
> +
> +template <class T1>
> +class A::ClassTemplatePartial<T1, T1 *> {}; // expected-warning {{class
> template partial specialization of 'ClassTemplatePartial' outside namespace
> enclosing 'A' is a Microsoft extension}}
> +
> +template <>
> +struct A::X<int>::MemberClass; // expected-warning {{member class
> specialization of 'MemberClass' outside namespace enclosing 'A' is a
> Microsoft extension}}
> +
> +template <>
> +enum A::X<int>::MemberEnumeration; // expected-warning {{member
> enumeration specialization of 'MemberEnumeration' outside namespace
> enclosing 'A' is a Microsoft extension}}
> +
> +}
> +
> Index: llvm/tools/clang/include/clang/Basic/DiagnosticSemaKinds.td
> ===================================================================
> --- llvm/tools/clang/include/clang/Basic/DiagnosticSemaKinds.td
> +++ llvm/tools/clang/include/clang/Basic/DiagnosticSemaKinds.td
> @@ -3445,6 +3445,12 @@
>    "variable template partial|function template|member "
>    "function|static data member|member class|member enumeration}0 "
>    "specialization of %1 not in a namespace enclosing %2">;
> +def ext_ms_template_spec_redecl_out_of_scope: ExtWarn<
> +  "%select{class template|class template partial|variable template|"
> +  "variable template partial|function template|member "
> +  "function|static data member|member class|member enumeration}0 "
> +  "specialization of %1 outside namespace enclosing %2 "
> +  "is a Microsoft extension">, InGroup<Microsoft>;
>  def err_template_spec_redecl_global_scope : Error<
>    "%select{class template|class template partial|variable template|"
>    "variable template partial|function template|member "
> Index: llvm/tools/clang/lib/Sema/SemaTemplate.cpp
> ===================================================================
> --- llvm/tools/clang/lib/Sema/SemaTemplate.cpp
> +++ llvm/tools/clang/lib/Sema/SemaTemplate.cpp
> @@ -5835,11 +5835,13 @@
>      if (isa<TranslationUnitDecl>(SpecializedContext))
>        S.Diag(Loc, diag::err_template_spec_redecl_global_scope)
>          << EntityKind << Specialized;
> -    else if (isa<NamespaceDecl>(SpecializedContext))
> -      S.Diag(Loc, diag::err_template_spec_redecl_out_of_scope)
> -        << EntityKind << Specialized
> -        << cast<NamedDecl>(SpecializedContext);
> -    else
> +    else if (isa<NamespaceDecl>(SpecializedContext)) {
> +      int Diag = diag::err_template_spec_redecl_out_of_scope;
> +      if (S.getLangOpts().MSVCCompat)
> +        Diag = diag::ext_ms_template_spec_redecl_out_of_scope;
> +      S.Diag(Loc, Diag) << EntityKind << Specialized
> +                        << cast<NamedDecl>(SpecializedContext);
> +    } else
>        llvm_unreachable("unexpected namespace context for specialization");
>
>      S.Diag(Specialized->getLocation(), diag::note_specialized_entity);
>
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