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Workaround compilers mishandling template-template arguments
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Visual Studio 2013 Update 4 and Clang 3.4 fail to parse
valptridx_template_t related argument lists because they misinterpret
the unspecialized inner template name as a reference to the current
specialization.  This seems to be nonconforming in C++11.

All gcc versions supported by Rebirth parse this sample program
correctly, but neither Visual Studio nor clang accept it.

    template <template <typename> class>
    struct A
    {
    };

    template <typename>
    struct B
    {
	    B(A<B>);
    };

In <https://stackoverflow.com/questions/17687459/clang-not-accepting-use-of-template-template-parameter-when-using-crtp>, a user saw a similar failure and received the answer:
    Your code is legal.

    From the C++11 Standard, section 14.6.1:

	Like normal (non-template) classes, class templates have an injected-class-name (Clause 9). The injected-class-name can be used as a template-name or a type-name. When it is used with a template-argument-list, as a template-argument for a template template-parameter, or as the final identifier in the elaborated-type- specifier of a friend class template declaration, it refers to the class template itself.

    Looks like your version of clang is still implementing the old rule.

This failure was first seen with Visual Studio 2013, but ignored because
Visual Studio has so many other problems parsing Rebirth.  Now that it
has been reported to affect clang as well, a workaround is clearly
needed.  A fix was suggested by btb
<2f9543f>,
but that fix breaks gcc.

Rewrite the valptridx_template_t parameter passing to avoid mentioning
unspecialized template names as template parameters while defining the
class used as the parameter.

Reported by btb (clang): dxx-rebirth#12
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@vLKp
vLKp committed Nov 30, 2014
1 parent cf31cc4 commit 690dec3
Showing 1 changed file with 48 additions and 41 deletions.
89 changes: 48 additions & 41 deletions common/include/valptridx.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -84,10 +84,7 @@ template <typename P, typename I, template <I> class magic_constant>
class validx_t;

template <
template <typename, typename> class VP0,
template <typename, typename I, template <I> class> class VI0,
template <typename, typename> class VP1,
template <typename, typename I, template <I> class> class VI1,
bool require_valid,
typename P, typename I, template <I> class magic_constant,
typename Prc = typename tt::remove_const<P>::type>
struct valptridx_template_t;
Expand Down Expand Up @@ -117,22 +114,22 @@ class valptr_t : protected valbaseptridxutil_t<P, I>
valptr_t(vvalptr_t<Prc, I> &&) = delete;
valptr_t(std::nullptr_t) : p(nullptr) {}
template <template <I> class magic_constant>
valptr_t(valptridx_template_t<vvalptr_t, vvalidx_t, valptr_t, validx_t, const P, I, magic_constant> v) :
valptr_t(valptridx_template_t<true, const P, I, magic_constant> v) :
p(v)
{
}
template <template <I> class magic_constant>
valptr_t(valptridx_template_t<vvalptr_t, vvalidx_t, valptr_t, validx_t, Prc, I, magic_constant> v) :
valptr_t(valptridx_template_t<true, Prc, I, magic_constant> v) :
p(v)
{
}
template <template <I> class magic_constant>
valptr_t(valptridx_template_t<valptr_t, validx_t, vvalptr_t, vvalidx_t, const P, I, magic_constant> v) :
valptr_t(valptridx_template_t<false, const P, I, magic_constant> v) :
p(v)
{
}
template <template <I> class magic_constant>
valptr_t(valptridx_template_t<valptr_t, validx_t, vvalptr_t, vvalidx_t, Prc, I, magic_constant> v) :
valptr_t(valptridx_template_t<false, Prc, I, magic_constant> v) :
p(v)
{
}
Expand Down Expand Up @@ -249,21 +246,34 @@ class validx_t : protected valbaseptridxutil_t<P, I>
index_type i;
};

template <bool, typename P, typename I, template <I> class magic_constant>
struct valptridx_dispatch_require_valid
{
typedef valptr_t<P, I> vptr_type;
typedef validx_t<P, I, magic_constant> vidx_type;
};

template <typename P, typename I, template <I> class magic_constant>
struct valptridx_dispatch_require_valid<true, P, I, magic_constant>
{
typedef vvalptr_t<P, I> vptr_type;
typedef vvalidx_t<P, I, magic_constant> vidx_type;
};

/*
* A data type for passing both a pointer and its offset in an
* agreed-upon array. Useful for Segments, Objects.
*/
template <
template <typename, typename> class VP0,
template <typename, typename I, template <I> class> class VI0,
template <typename, typename> class VP1,
template <typename, typename I, template <I> class> class VI1,
bool require_valid,
typename P, typename I, template <I> class magic_constant,
typename Prc>
struct valptridx_template_t : VP0<P, I>, VI0<P, I, magic_constant>
struct valptridx_template_t :
valptridx_dispatch_require_valid<require_valid, P, I, magic_constant>::vptr_type,
valptridx_dispatch_require_valid<require_valid, P, I, magic_constant>::vidx_type
{
typedef VP0<P, I> vptr_type;
typedef VI0<P, I, magic_constant> vidx_type;
typedef typename valptridx_dispatch_require_valid<require_valid, P, I, magic_constant>::vptr_type vptr_type;
typedef typename valptridx_dispatch_require_valid<require_valid, P, I, magic_constant>::vidx_type vidx_type;
typedef valptridx_template_t valptridx_type;
protected:
using vidx_type::get_array;
Expand All @@ -280,30 +290,30 @@ struct valptridx_template_t : VP0<P, I>, VI0<P, I, magic_constant>
valptridx_template_t() = delete;
valptridx_template_t(std::nullptr_t) = delete;
/* Swapped V0/V1 matches rvalue construction to/from always-valid type */
valptridx_template_t(valptridx_template_t<VP1, VI1, VP0, VI0, const P, I, magic_constant> &&) = delete;
valptridx_template_t(valptridx_template_t<VP1, VI1, VP0, VI0, Prc, I, magic_constant> &&) = delete;
valptridx_template_t(valptridx_template_t<!require_valid, const P, I, magic_constant> &&) = delete;
valptridx_template_t(valptridx_template_t<!require_valid, Prc, I, magic_constant> &&) = delete;
/* Convenience conversion to/from always-valid. Throws on attempt
* to make an always-valid from an invalid maybe-valid.
*/
valptridx_template_t(const valptridx_template_t<VP1, VI1, VP0, VI0, const P, I, magic_constant> &t) :
vptr_type(t.operator const VP1<const P, I> &()),
vidx_type(t.operator const VI1<const P, I, magic_constant> &())
valptridx_template_t(const valptridx_template_t<!require_valid, const P, I, magic_constant> &t) :
vptr_type(t.operator const typename valptridx_dispatch_require_valid<!require_valid, const P, I, magic_constant>::vptr_type &()),
vidx_type(t.operator const typename valptridx_dispatch_require_valid<!require_valid, const P, I, magic_constant>::vidx_type &())
{
}
valptridx_template_t(const valptridx_template_t<VP1, VI1, VP0, VI0, Prc, I, magic_constant> &t) :
vptr_type(t.operator const VP1<Prc, I> &()),
vidx_type(t.operator const VI1<Prc, I, magic_constant> &())
valptridx_template_t(const valptridx_template_t<!require_valid, Prc, I, magic_constant> &t) :
vptr_type(t.operator const typename valptridx_dispatch_require_valid<!require_valid, Prc, I, magic_constant>::vptr_type &()),
vidx_type(t.operator const typename valptridx_dispatch_require_valid<!require_valid, Prc, I, magic_constant>::vidx_type &())
{
}
/* Copy construction from like type, possibly const-qualified */
valptridx_template_t(const valptridx_template_t<VP0, VI0, VP1, VI1, const P, I, magic_constant> &t) :
vptr_type(t.operator const VP0<const P, I> &()),
vidx_type(t.operator const VI0<const P, I, magic_constant> &())
valptridx_template_t(const valptridx_template_t<require_valid, const P, I, magic_constant> &t) :
vptr_type(t.operator const typename valptridx_dispatch_require_valid<require_valid, const P, I, magic_constant>::vptr_type &()),
vidx_type(t.operator const typename valptridx_dispatch_require_valid<require_valid, const P, I, magic_constant>::vidx_type &())
{
}
valptridx_template_t(const valptridx_template_t<VP0, VI0, VP1, VI1, Prc, I, magic_constant> &t) :
vptr_type(t.operator const VP0<Prc, I> &()),
vidx_type(t.operator const VI0<Prc, I, magic_constant> &())
valptridx_template_t(const valptridx_template_t<require_valid, Prc, I, magic_constant> &t) :
vptr_type(t.operator const typename valptridx_dispatch_require_valid<require_valid, Prc, I, magic_constant>::vptr_type &()),
vidx_type(t.operator const typename valptridx_dispatch_require_valid<require_valid, Prc, I, magic_constant>::vidx_type &())
{
}
template <integral_type v>
Expand Down Expand Up @@ -341,17 +351,14 @@ struct valptridx_template_t : VP0<P, I>, VI0<P, I, magic_constant>
{
}
template <
template <typename, typename> class EP0,
template <typename, typename EI, template <EI> class> class EI0,
template <typename, typename> class EP1,
template <typename, typename EI, template <EI> class> class EI1,
bool erv,
typename EP>
/* Reuse Prc to enforce is_same<remove_const<EP>::type,
* remove_const<P>::type>.
*/
bool operator==(const valptridx_template_t<EP0, EI0, EP1, EI1, EP, I, magic_constant, Prc> &rhs) const
bool operator==(const valptridx_template_t<erv, EP, I, magic_constant, Prc> &rhs) const
{
typedef valptridx_template_t<EP0, EI0, EP1, EI1, EP, I, magic_constant, Prc> rhs_t;
typedef valptridx_template_t<erv, EP, I, magic_constant, Prc> rhs_t;
return vptr_type::operator==(rhs.operator const typename rhs_t::vptr_type &()) &&
vidx_type::operator==(rhs.operator const typename rhs_t::vidx_type &());
}
Expand Down Expand Up @@ -429,22 +436,22 @@ class vvalptr_t : public valptr_t<P, I>
{
}
template <template <I> class magic_constant>
vvalptr_t(valptridx_template_t<vvalptr_t, vvalidx_t, valptr_t, validx_t, const P, I, magic_constant> v) :
vvalptr_t(valptridx_template_t<true, const P, I, magic_constant> v) :
base_t(v)
{
}
template <template <I> class magic_constant>
vvalptr_t(valptridx_template_t<vvalptr_t, vvalidx_t, valptr_t, validx_t, Prc, I, magic_constant> v) :
vvalptr_t(valptridx_template_t<true, Prc, I, magic_constant> v) :
base_t(v)
{
}
template <template <I> class magic_constant>
vvalptr_t(valptridx_template_t<valptr_t, validx_t, vvalptr_t, vvalidx_t, const P, I, magic_constant> v) :
vvalptr_t(valptridx_template_t<false, const P, I, magic_constant> v) :
base_t(check_null_pointer(static_cast<const P *>(v)))
{
}
template <template <I> class magic_constant>
vvalptr_t(valptridx_template_t<valptr_t, validx_t, vvalptr_t, vvalidx_t, Prc, I, magic_constant> v) :
vvalptr_t(valptridx_template_t<false, Prc, I, magic_constant> v) :
base_t(check_null_pointer(static_cast<Prc *>(v)))
{
}
Expand Down Expand Up @@ -575,11 +582,11 @@ struct vvalptridx_functions : valptridx_functions<A, a, vptridx>
DXX_INHERIT_CONSTRUCTORS(v##prefix##ptr_t, valptr_type); \
}; \
\
struct prefix##ptridx_t : valptridx_template_t<valptr_t, validx_t, vvalptr_t, vvalidx_t, P Pconst, I, P##_magic_constant_t> { \
struct prefix##ptridx_t : valptridx_template_t<false, P Pconst, I, P##_magic_constant_t> { \
DXX_INHERIT_CONSTRUCTORS(prefix##ptridx_t, valptridx_type); \
}; \
\
struct v##prefix##ptridx_t : valptridx_template_t<vvalptr_t, vvalidx_t, valptr_t, validx_t, P Pconst, I, P##_magic_constant_t> { \
struct v##prefix##ptridx_t : valptridx_template_t<true, P Pconst, I, P##_magic_constant_t> { \
DXX_INHERIT_CONSTRUCTORS(v##prefix##ptridx_t, valptridx_type); \
}; \
\
Expand Down

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