On Fri, Jun 26, 2015 at 7:40 AM, Patrick Palka <patr...@parcs.ath.cx> wrote:
> Here is a more modest approach to fixing this PR. Instead of updating
> current_template_parms with each newly processed template parameter,
> this patch just updates it with a "dummy" parameter level once per
> parameter list. So now in tsubst(), to fix the reported ICE we just
> have to avoid substituting a template parameter if it corresponds to an
> empty "dummy" argument level.
>
> One caveat with this approach is that since template template decls will
> now have dummy parameter levels in their DECL_TEMPLATE_PARMS fields, we
> have to avoid emitting such dummy levels inside error messages when
> printing template template parameters. Otherwise the parameter B in
>
> template<template<class A> class B> struct Foo { };
>
> would get printed in error messages as
>
> template<> template <class A> class B>
>
> Two new test files are added in this version: shadow2.C, which checks
> that we emit a shadowing error for identical template parameter names
> across nested parameter lists, and error55.C, which checks that we
> correctly emit template template decls in error messages.
>
> With this approach the test case provided by Markus no longer takes
> forever to compile because the added parameter lists are always empty so
> when doing structural type comparison of a TEMPLATE_TEMPLATE_PARM there
> is nothing extra to recurse into.
>
> Does this approach seem sensible?
>
> gcc/cp/ChangeLog:
>
> PR c++/30044
> * pt.c (begin_template_parm_list): Add a dummy parameter level
> to current_template_parms.
> (end_template_parm_list): Remove the dummy parameter level
> before adding the real one.
> (tsubst): Don't attempt to substitute for template parameters
> corresponding to a dummy argument level.
> (template_parms_to_args): Remove obsolete hack for
> giving template template arguments the proper level.
> (splite_late_return_type): Remove obsolete hack for giving
> template template arguments the proper level.
> * error.c (dump_template_decl): Don't print dummy template
> levels.
>
> gcc/testsuite/ChangeLog
>
> PR c++/30044
> * g++.dg/cpp0x/auto45.C: New test.
> * g++.dg/template/pr30044.C: New test.
> * g++.dg/template/shadow2.C: New test.
> * g++.dg/template/error55.C: New test.
> * g++.dg/template/crash83.C: Accept any error string.
> * g++.dg/cpp0x/variadic18.C: Adjust to avoid shadowing template
> parameters.
> * g++.dg/cpp0x/variadic18.C: Likewise
> * g++.dg/template/canon-type-13.C: Likewise.
> * g++.old-deja/g++.pt/ttp42.C: Likewise.
> * g++.dg/torture/20070621-1.C: Likewise.
> ---
> gcc/cp/error.c | 7 ++++++
> gcc/cp/pt.c | 32
> +++++++++------------------
> gcc/testsuite/g++.dg/cpp0x/auto45.C | 5 +++++
> gcc/testsuite/g++.dg/cpp0x/variadic18.C | 2 +-
> gcc/testsuite/g++.dg/cpp0x/variadic19.C | 2 +-
> gcc/testsuite/g++.dg/template/canon-type-13.C | 2 +-
> gcc/testsuite/g++.dg/template/crash83.C | 2 +-
> gcc/testsuite/g++.dg/template/error55.C | 8 +++++++
> gcc/testsuite/g++.dg/template/pr30044.C | 14 ++++++++++++
> gcc/testsuite/g++.dg/template/shadow2.C | 3 +++
> gcc/testsuite/g++.dg/torture/20070621-1.C | 2 +-
> gcc/testsuite/g++.old-deja/g++.pt/ttp42.C | 2 +-
> 12 files changed, 54 insertions(+), 27 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/cpp0x/auto45.C
> create mode 100644 gcc/testsuite/g++.dg/template/error55.C
> create mode 100644 gcc/testsuite/g++.dg/template/pr30044.C
> create mode 100644 gcc/testsuite/g++.dg/template/shadow2.C
>
> diff --git a/gcc/cp/error.c b/gcc/cp/error.c
> index 96fa94d..b21befe 100644
> --- a/gcc/cp/error.c
> +++ b/gcc/cp/error.c
> @@ -1296,6 +1296,13 @@ dump_template_decl (cxx_pretty_printer *pp, tree t,
> int flags)
> tree inner_parms = INNERMOST_TEMPLATE_PARMS (parms);
> int len = TREE_VEC_LENGTH (inner_parms);
>
> + if (len == 0)
> + {
> + /* Skip over the dummy template levels of a template template
> parm. */
> + gcc_assert (TREE_CODE (TREE_TYPE (t)) ==
> TEMPLATE_TEMPLATE_PARM);
> + continue;
> + }
> +
> pp_cxx_ws_string (pp, "template");
> pp_cxx_begin_template_argument_list (pp);
>
> diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
> index fe5fc14..e7c35d3 100644
> --- a/gcc/cp/pt.c
> +++ b/gcc/cp/pt.c
> @@ -658,6 +658,12 @@ begin_template_parm_list (void)
> ++processing_template_decl;
> ++processing_template_parmlist;
> note_template_header (0);
> +
> + /* Add a dummy parameter level while we process the parameter list. */
> + current_template_parms
> + = tree_cons (size_int (processing_template_decl),
> + make_tree_vec (0),
> + current_template_parms);
> }
>
> /* This routine is called when a specialization is declared. If it is
> @@ -3854,6 +3860,9 @@ end_template_parm_list (tree parms)
> tree parm, next;
> tree saved_parmlist = make_tree_vec (list_length (parms));
>
> + /* Pop the dummy parameter level and add the real one. */
> + current_template_parms = TREE_CHAIN (current_template_parms);
> +
> current_template_parms
> = tree_cons (size_int (processing_template_decl),
> saved_parmlist, current_template_parms);
> @@ -3989,21 +3998,6 @@ template_parms_to_args (tree parms)
> args = a;
> }
>
> - if (length > 1 && TREE_VEC_ELT (args, 0) == NULL_TREE)
> - /* This can happen for template parms of a template template
> - parameter, e.g:
> -
> - template<template<class T, class U> class TT> struct S;
> -
> - Consider the level of the parms of TT; T and U both have
> - level 2; TT has no template parm of level 1. So in this case
> - the first element of full_template_args is NULL_TREE. If we
> - leave it like this TMPL_ARGS_DEPTH on args returns 1 instead
> - of 2. This will make tsubst wrongly consider that T and U
> - have level 1. Instead, let's create a dummy vector as the
> - first element of full_template_args so that TMPL_ARGS_DEPTH
> - returns the correct depth for args. */
> - TREE_VEC_ELT (args, 0) = make_tree_vec (1);
> return args;
> }
>
> @@ -12029,7 +12023,8 @@ tsubst (tree t, tree args, tsubst_flags_t complain,
> tree in_decl)
> template_parm_level_and_index (t, &level, &idx);
>
> levels = TMPL_ARGS_DEPTH (args);
> - if (level <= levels)
> + if (level <= levels
> + && TREE_VEC_LENGTH (TMPL_ARGS_LEVEL (args, level)) > 0)
> {
> arg = TMPL_ARG (args, level, idx);
>
> @@ -22394,11 +22389,6 @@ splice_late_return_type (tree type, tree
> late_return_type)
> return type;
> argvec = make_tree_vec (1);
> TREE_VEC_ELT (argvec, 0) = late_return_type;
> - if (processing_template_parmlist)
> - /* For a late-specified return type in a template type-parameter, we
> - need to add a dummy argument level for its parmlist. */
> - argvec = add_to_template_args
> - (make_tree_vec (processing_template_parmlist), argvec);
> if (current_template_parms)
> argvec = add_to_template_args (current_template_args (), argvec);
> return tsubst (type, argvec, tf_warning_or_error, NULL_TREE);
> diff --git a/gcc/testsuite/g++.dg/cpp0x/auto45.C
> b/gcc/testsuite/g++.dg/cpp0x/auto45.C
> new file mode 100644
> index 0000000..09e9f44
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/auto45.C
> @@ -0,0 +1,5 @@
> +// Addendum to auto23.C, now with nested template parameter lists
> +// { dg-do compile { target c++11 } }
> +
> +template<template <auto f()->int> class> struct A { };
> +template<template <template <auto f()->int> class> class> struct B { };
> diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic18.C
> b/gcc/testsuite/g++.dg/cpp0x/variadic18.C
> index fc0e2dd..57fdc86 100644
> --- a/gcc/testsuite/g++.dg/cpp0x/variadic18.C
> +++ b/gcc/testsuite/g++.dg/cpp0x/variadic18.C
> @@ -1,7 +1,7 @@
> // { dg-do compile { target c++11 } }
> template<typename...> class tuple { };
>
> -template<typename T, template<typename T> class... Metafunctions>
> +template<typename T, template<typename U> class... Metafunctions>
> struct apply_all
> {
> typedef tuple<typename Metafunctions<T>::type...> type;
> diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic19.C
> b/gcc/testsuite/g++.dg/cpp0x/variadic19.C
> index 0ae2672..3be9bb0 100644
> --- a/gcc/testsuite/g++.dg/cpp0x/variadic19.C
> +++ b/gcc/testsuite/g++.dg/cpp0x/variadic19.C
> @@ -4,7 +4,7 @@ struct tuple {
> static const int value = 0;
> };
>
> -template<typename T, template<class T> class... Metafunctions>
> +template<typename T, template<class U> class... Metafunctions>
> struct tuple<Metafunctions<T>...> {
> static const int value = 1;
> };
> diff --git a/gcc/testsuite/g++.dg/template/canon-type-13.C
> b/gcc/testsuite/g++.dg/template/canon-type-13.C
> index 4f3702b..5a8d37d 100644
> --- a/gcc/testsuite/g++.dg/template/canon-type-13.C
> +++ b/gcc/testsuite/g++.dg/template/canon-type-13.C
> @@ -11,7 +11,7 @@ struct S1
> {
> };
>
> -template<class T, template<class T> class A, template<class T> class B = A>
> +template<class T, template<class U> class A, template<class U> class B = A>
> struct C
> {
> B<T> m;
> diff --git a/gcc/testsuite/g++.dg/template/crash83.C
> b/gcc/testsuite/g++.dg/template/crash83.C
> index b83dd21..7dcbed9 100644
> --- a/gcc/testsuite/g++.dg/template/crash83.C
> +++ b/gcc/testsuite/g++.dg/template/crash83.C
> @@ -2,4 +2,4 @@
>
> template<int> struct A {};
>
> -template<typename = class A<0>: > struct B {}; // { dg-error "explicit
> specialization|expected" }
> +template<typename = class A<0>: > struct B {}; // { dg-error "" }
> diff --git a/gcc/testsuite/g++.dg/template/error55.C
> b/gcc/testsuite/g++.dg/template/error55.C
> new file mode 100644
> index 0000000..41f9595
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/template/error55.C
> @@ -0,0 +1,8 @@
> +// Check that template template parameters get printed properly in error
> +// messages.
> +
> +template <template <class A> class B>
> +struct Y
> +{
> + B<5> y; // { dg-error "for 'template<class A> class B'" }
> +};
> diff --git a/gcc/testsuite/g++.dg/template/pr30044.C
> b/gcc/testsuite/g++.dg/template/pr30044.C
> new file mode 100644
> index 0000000..415e6f0
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/template/pr30044.C
> @@ -0,0 +1,14 @@
> +// PR c++/30044
> +
> +template <typename T1, typename T2, template <T2> class Comp, class Result =
> Comp<1> >
> +struct sort { };
> +
> +
> +template <typename Type, template <Type, Type> class Comp, class Result =
> Comp<1, 2> >
> +struct sort2 { };
> +
> +template <typename Type, template <int, Type> class Comp, class Result =
> Comp<1, 2> >
> +struct sort3 { };
> +
> +template <template <typename T1, typename T2, template <T2> class Comp,
> class Result = Comp<1> > class Foo>
> +struct sort4 { };
> diff --git a/gcc/testsuite/g++.dg/template/shadow2.C
> b/gcc/testsuite/g++.dg/template/shadow2.C
> new file mode 100644
> index 0000000..7f6a6dc
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/template/shadow2.C
> @@ -0,0 +1,3 @@
> +template <class A, // { dg-error "shadows template parm 'class A'" }
> + template <class A> class B> // { dg-error "declaration of 'class
> A'" }
> +class X;
> diff --git a/gcc/testsuite/g++.dg/torture/20070621-1.C
> b/gcc/testsuite/g++.dg/torture/20070621-1.C
> index 15d1ac7..9bd8cc3 100644
> --- a/gcc/testsuite/g++.dg/torture/20070621-1.C
> +++ b/gcc/testsuite/g++.dg/torture/20070621-1.C
> @@ -89,7 +89,7 @@ namespace __gnu_test {
> SharedInfo->first=ptr;
> }
> };
> - template <class T, template<class T> class ItType> struct
> test_container {
> + template <class T, template<class U> class ItType> struct
> test_container {
> typename ItType<T>::ContainerType bounds;
> test_container(T* _first, T* _last):bounds(_first, _last) {
> }
> diff --git a/gcc/testsuite/g++.old-deja/g++.pt/ttp42.C
> b/gcc/testsuite/g++.old-deja/g++.pt/ttp42.C
> index 53bdae1..a2ac239 100644
> --- a/gcc/testsuite/g++.old-deja/g++.pt/ttp42.C
> +++ b/gcc/testsuite/g++.old-deja/g++.pt/ttp42.C
> @@ -1,5 +1,5 @@
> // { dg-do run }
> -template <class T, template <class T> class C>
> +template <class T, template <class U> class C>
> struct X
> {};
>
> --
> 2.5.0.rc0.5.g91e10c5.dirty
>
Ping.
