* [PATCH] c++: Relax rules for non-type arguments in partial specs [CWG1315]
@ 2021-05-26 23:36 Patrick Palka
2021-05-27 13:22 ` Jason Merrill
0 siblings, 1 reply; 2+ messages in thread
From: Patrick Palka @ 2021-05-26 23:36 UTC (permalink / raw)
To: gcc-patches
This implements the wording changes of CWG 1315, which permits non-type
template arguments in a partial specialization to use template
parameters more freely. Delightfully, it seems the only change needed
is to remove a few checks from process_partial_specialization.
But that change alone revealed a latent problem with
for_each_template_parm: it ends up looking into some non-deduced
contexts even when include_nondeduced_p is false. This causes us to
silently accept some partial specializations within the testsuite that
contain non-deducible non-type template parameters (and that were
previously rejected due to the rule that CWG 1315 removed). For now
this patch makes a minimal amount of changes to for_each_template_parm_r
so we continue to reject existing ill-formed partial specializations
within the testsuite.
Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk? Patch generated with -w to hide noisy whitespace changes.
DR 1315
PR c++/96555
PR c++/100779
gcc/cp/ChangeLog:
* pt.c (process_partial_specialization): Don't error on a
non-simple non-type template argument that involves template
parameters.
(for_each_template_parm_r): Don't walk TRAIT_EXPR, PLUS_EXPR,
MULT_EXPR, or SCOPE_REF when include_nondeduced_p is unset.
gcc/testsuite/ChangeLog:
* g++.dg/template/partial16.C: New test.
* g++.dg/template/partial17.C: New test.
* g++.dg/template/partial18.C: New test.
* g++.dg/cpp0x/pr68724.C: Adjust expected diagnostic for
ill-formed partial specialization.
* g++.dg/cpp0x/variadic38.C: Likewise.
* g++.dg/cpp1z/pr81016.C: Likewise.
* g++.dg/template/partial5.C: Likewise.
* g++.old-deja/g++.pt/spec21.C: Likewise.
---
gcc/cp/pt.c | 28 ++++++++--------------
gcc/testsuite/g++.dg/cpp0x/pr68724.C | 2 +-
gcc/testsuite/g++.dg/cpp0x/variadic38.C | 3 ++-
gcc/testsuite/g++.dg/cpp1z/pr81016.C | 2 +-
gcc/testsuite/g++.dg/template/partial16.C | 8 +++++++
gcc/testsuite/g++.dg/template/partial17.C | 14 +++++++++++
gcc/testsuite/g++.dg/template/partial18.C | 19 +++++++++++++++
gcc/testsuite/g++.dg/template/partial5.C | 2 +-
gcc/testsuite/g++.old-deja/g++.pt/spec21.C | 3 +--
9 files changed, 57 insertions(+), 24 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/template/partial16.C
create mode 100644 gcc/testsuite/g++.dg/template/partial17.C
create mode 100644 gcc/testsuite/g++.dg/template/partial18.C
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index f3fa9c192ad..6b0bc815404 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -5157,11 +5157,7 @@ process_partial_specialization (tree decl)
maintmpl);
}
- /* [temp.class.spec]
-
- A partially specialized non-type argument expression shall not
- involve template parameters of the partial specialization except
- when the argument expression is a simple identifier.
+ /* [temp.spec.partial]
The type of a template parameter corresponding to a specialized
non-type argument shall not be dependent on a parameter of the
@@ -5221,13 +5217,6 @@ process_partial_specialization (tree decl)
&& !((REFERENCE_REF_P (arg)
|| TREE_CODE (arg) == VIEW_CONVERT_EXPR)
&& TREE_CODE (TREE_OPERAND (arg, 0)) == TEMPLATE_PARM_INDEX))
- {
- if ((!packed_args && tpd.arg_uses_template_parms[i])
- || (packed_args && uses_template_parms (arg)))
- error_at (cp_expr_loc_or_input_loc (arg),
- "template argument %qE involves template "
- "parameter(s)", arg);
- else
{
/* Look at the corresponding template parameter,
marking which template parameters its type depends
@@ -5281,7 +5270,6 @@ process_partial_specialization (tree decl)
}
}
}
- }
/* We should only get here once. */
if (TREE_CODE (decl) == TYPE_DECL)
@@ -10502,6 +10490,15 @@ for_each_template_parm_r (tree *tp, int *walk_subtrees, void *d)
return error_mark_node;
break;
+ case TRAIT_EXPR:
+ case PLUS_EXPR:
+ case MULT_EXPR:
+ case SCOPE_REF:
+ /* These are always non-deduced contexts. */
+ if (!pfd->include_nondeduced_p)
+ *walk_subtrees = 0;
+ break;
+
case MODOP_EXPR:
case CAST_EXPR:
case IMPLICIT_CONV_EXPR:
@@ -10517,11 +10514,6 @@ for_each_template_parm_r (tree *tp, int *walk_subtrees, void *d)
return error_mark_node;
break;
- case SCOPE_REF:
- if (pfd->include_nondeduced_p)
- WALK_SUBTREE (TREE_OPERAND (t, 0));
- break;
-
case REQUIRES_EXPR:
{
if (!fn)
diff --git a/gcc/testsuite/g++.dg/cpp0x/pr68724.C b/gcc/testsuite/g++.dg/cpp0x/pr68724.C
index 4e99d53d5a9..6df7f718a7e 100644
--- a/gcc/testsuite/g++.dg/cpp0x/pr68724.C
+++ b/gcc/testsuite/g++.dg/cpp0x/pr68724.C
@@ -9,7 +9,7 @@ struct integral_constant
integral_constant<bool, true> inst;
template <typename _Tp>
-struct integral_constant<bool, __is_enum(_Tp)> // { dg-error "32:template argument" }
+struct integral_constant<bool, __is_enum(_Tp)> // { dg-error "not deducible" }
{
};
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic38.C b/gcc/testsuite/g++.dg/cpp0x/variadic38.C
index b569404cdf2..9155445dce1 100644
--- a/gcc/testsuite/g++.dg/cpp0x/variadic38.C
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic38.C
@@ -3,4 +3,5 @@ template<int... Values>
struct int_vec {};
template<int... Values>
-struct int_vec<0, (Values+1)...> {}; // { dg-error "26:template argument" }
+struct int_vec<0, (Values+1)...> {}; // { dg-error "not deducible" }
+
diff --git a/gcc/testsuite/g++.dg/cpp1z/pr81016.C b/gcc/testsuite/g++.dg/cpp1z/pr81016.C
index 358b12056c0..a17afcc6b65 100644
--- a/gcc/testsuite/g++.dg/cpp1z/pr81016.C
+++ b/gcc/testsuite/g++.dg/cpp1z/pr81016.C
@@ -1,4 +1,4 @@
// { dg-do compile { target c++17 } }
template <typename a, a> struct b;
-template <typename c> struct b<bool, c::d>; // { dg-error "template parameter" }
+template <typename c> struct b<bool, c::d>; // { dg-error "not deducible" }
diff --git a/gcc/testsuite/g++.dg/template/partial16.C b/gcc/testsuite/g++.dg/template/partial16.C
new file mode 100644
index 00000000000..30c34c3e0d9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/partial16.C
@@ -0,0 +1,8 @@
+// [temp.spec.partial.general]/9
+
+template <class T, T t> struct C {};
+template <class T> struct C<T, 1>; // { dg-error "depends on a template parameter" }
+
+template< int X, int (*array_ptr)[X] > class A {};
+int array[5];
+template< int X > class A<X,&array> { }; // { dg-error "depends on a template parameter" }
diff --git a/gcc/testsuite/g++.dg/template/partial17.C b/gcc/testsuite/g++.dg/template/partial17.C
new file mode 100644
index 00000000000..d5c82d26db3
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/partial17.C
@@ -0,0 +1,14 @@
+// [temp.spec.partial.match]/3
+
+template <int I, int J> struct A;
+template <int I> struct A<I+5, I*2> {}; // { dg-error "not deducible" }
+
+template <int I> struct A<I, I> {}; // OK
+
+template <int I, int J, int K> struct B;
+template <int I> struct B<I, I*2, I> {}; // OK
+template <int I> struct B<I, I*2, 2> { typedef int type; }; // OK
+
+B<1, 2, 1> b1;
+B<1, 2, 2>::type b2;
+B<1, 2, 3> b3; // { dg-error "incomplete" }
diff --git a/gcc/testsuite/g++.dg/template/partial18.C b/gcc/testsuite/g++.dg/template/partial18.C
new file mode 100644
index 00000000000..7b7614ebc6b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/partial18.C
@@ -0,0 +1,19 @@
+// PR c++/96555
+
+template<class T, int i>
+struct X;
+
+template<class T>
+struct X<T, sizeof(T)> {};
+
+X<int, sizeof(int)> x1;
+X<int, sizeof(int)+1> x2; // { dg-error "incomplete" }
+
+
+struct A { int x; } a;
+template<int, int> struct B;
+template<int y>
+struct B<y, sizeof(a.x)> { };
+
+B<0, sizeof(int)> b1;
+B<0, sizeof(int)+1> b2; // { dg-error "incomplete" }
diff --git a/gcc/testsuite/g++.dg/template/partial5.C b/gcc/testsuite/g++.dg/template/partial5.C
index 40d8c45b087..037f684cbd2 100644
--- a/gcc/testsuite/g++.dg/template/partial5.C
+++ b/gcc/testsuite/g++.dg/template/partial5.C
@@ -21,4 +21,4 @@ template<typename T, T V>
struct Z { };
template<typename T>
-struct Z<T, (T)0> { }; // { dg-error "13:template argument" }
+struct Z<T, (T)0> { }; // { dg-error "depends on a template parameter" }
diff --git a/gcc/testsuite/g++.old-deja/g++.pt/spec21.C b/gcc/testsuite/g++.old-deja/g++.pt/spec21.C
index cf89d6b325a..bf25c0ebb39 100644
--- a/gcc/testsuite/g++.old-deja/g++.pt/spec21.C
+++ b/gcc/testsuite/g++.old-deja/g++.pt/spec21.C
@@ -4,8 +4,7 @@ template <class T> struct S {};
template <class T = int> struct S<T*> {}; // { dg-error "" } default argument
template <int I, int J> struct A {};
-template <int I> struct A<I+5, I*2> {}; // { dg-error "28:template argument" }
-// { dg-error "33:template argument" "" { target *-*-* } .-1 }
+template <int I> struct A<I+5, I*2> {}; // { dg-error "not deducible" }
template <class T, T t> struct C {};
template <class T> struct C<T, 1>; // { dg-error "" } type depends on parameter
int i;
--
2.32.0.rc0
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] c++: Relax rules for non-type arguments in partial specs [CWG1315]
2021-05-26 23:36 [PATCH] c++: Relax rules for non-type arguments in partial specs [CWG1315] Patrick Palka
@ 2021-05-27 13:22 ` Jason Merrill
0 siblings, 0 replies; 2+ messages in thread
From: Jason Merrill @ 2021-05-27 13:22 UTC (permalink / raw)
To: Patrick Palka, gcc-patches
On 5/26/21 7:36 PM, Patrick Palka wrote:
> This implements the wording changes of CWG 1315, which permits non-type
> template arguments in a partial specialization to use template
> parameters more freely. Delightfully, it seems the only change needed
> is to remove a few checks from process_partial_specialization.
>
> But that change alone revealed a latent problem with
> for_each_template_parm: it ends up looking into some non-deduced
> contexts even when include_nondeduced_p is false. This causes us to
> silently accept some partial specializations within the testsuite that
> contain non-deducible non-type template parameters (and that were
> previously rejected due to the rule that CWG 1315 removed). For now
> this patch makes a minimal amount of changes to for_each_template_parm_r
> so we continue to reject existing ill-formed partial specializations
> within the testsuite.
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> trunk? Patch generated with -w to hide noisy whitespace changes.
OK.
> DR 1315
> PR c++/96555
> PR c++/100779
>
> gcc/cp/ChangeLog:
>
> * pt.c (process_partial_specialization): Don't error on a
> non-simple non-type template argument that involves template
> parameters.
> (for_each_template_parm_r): Don't walk TRAIT_EXPR, PLUS_EXPR,
> MULT_EXPR, or SCOPE_REF when include_nondeduced_p is unset.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/template/partial16.C: New test.
> * g++.dg/template/partial17.C: New test.
> * g++.dg/template/partial18.C: New test.
> * g++.dg/cpp0x/pr68724.C: Adjust expected diagnostic for
> ill-formed partial specialization.
> * g++.dg/cpp0x/variadic38.C: Likewise.
> * g++.dg/cpp1z/pr81016.C: Likewise.
> * g++.dg/template/partial5.C: Likewise.
> * g++.old-deja/g++.pt/spec21.C: Likewise.
> ---
> gcc/cp/pt.c | 28 ++++++++--------------
> gcc/testsuite/g++.dg/cpp0x/pr68724.C | 2 +-
> gcc/testsuite/g++.dg/cpp0x/variadic38.C | 3 ++-
> gcc/testsuite/g++.dg/cpp1z/pr81016.C | 2 +-
> gcc/testsuite/g++.dg/template/partial16.C | 8 +++++++
> gcc/testsuite/g++.dg/template/partial17.C | 14 +++++++++++
> gcc/testsuite/g++.dg/template/partial18.C | 19 +++++++++++++++
> gcc/testsuite/g++.dg/template/partial5.C | 2 +-
> gcc/testsuite/g++.old-deja/g++.pt/spec21.C | 3 +--
> 9 files changed, 57 insertions(+), 24 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/template/partial16.C
> create mode 100644 gcc/testsuite/g++.dg/template/partial17.C
> create mode 100644 gcc/testsuite/g++.dg/template/partial18.C
>
> diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
> index f3fa9c192ad..6b0bc815404 100644
> --- a/gcc/cp/pt.c
> +++ b/gcc/cp/pt.c
> @@ -5157,11 +5157,7 @@ process_partial_specialization (tree decl)
> maintmpl);
> }
>
> - /* [temp.class.spec]
> -
> - A partially specialized non-type argument expression shall not
> - involve template parameters of the partial specialization except
> - when the argument expression is a simple identifier.
> + /* [temp.spec.partial]
>
> The type of a template parameter corresponding to a specialized
> non-type argument shall not be dependent on a parameter of the
> @@ -5221,13 +5217,6 @@ process_partial_specialization (tree decl)
> && !((REFERENCE_REF_P (arg)
> || TREE_CODE (arg) == VIEW_CONVERT_EXPR)
> && TREE_CODE (TREE_OPERAND (arg, 0)) == TEMPLATE_PARM_INDEX))
> - {
> - if ((!packed_args && tpd.arg_uses_template_parms[i])
> - || (packed_args && uses_template_parms (arg)))
> - error_at (cp_expr_loc_or_input_loc (arg),
> - "template argument %qE involves template "
> - "parameter(s)", arg);
> - else
> {
> /* Look at the corresponding template parameter,
> marking which template parameters its type depends
> @@ -5281,7 +5270,6 @@ process_partial_specialization (tree decl)
> }
> }
> }
> - }
>
> /* We should only get here once. */
> if (TREE_CODE (decl) == TYPE_DECL)
> @@ -10502,6 +10490,15 @@ for_each_template_parm_r (tree *tp, int *walk_subtrees, void *d)
> return error_mark_node;
> break;
>
> + case TRAIT_EXPR:
> + case PLUS_EXPR:
> + case MULT_EXPR:
> + case SCOPE_REF:
> + /* These are always non-deduced contexts. */
> + if (!pfd->include_nondeduced_p)
> + *walk_subtrees = 0;
> + break;
> +
> case MODOP_EXPR:
> case CAST_EXPR:
> case IMPLICIT_CONV_EXPR:
> @@ -10517,11 +10514,6 @@ for_each_template_parm_r (tree *tp, int *walk_subtrees, void *d)
> return error_mark_node;
> break;
>
> - case SCOPE_REF:
> - if (pfd->include_nondeduced_p)
> - WALK_SUBTREE (TREE_OPERAND (t, 0));
> - break;
> -
> case REQUIRES_EXPR:
> {
> if (!fn)
> diff --git a/gcc/testsuite/g++.dg/cpp0x/pr68724.C b/gcc/testsuite/g++.dg/cpp0x/pr68724.C
> index 4e99d53d5a9..6df7f718a7e 100644
> --- a/gcc/testsuite/g++.dg/cpp0x/pr68724.C
> +++ b/gcc/testsuite/g++.dg/cpp0x/pr68724.C
> @@ -9,7 +9,7 @@ struct integral_constant
> integral_constant<bool, true> inst;
>
> template <typename _Tp>
> -struct integral_constant<bool, __is_enum(_Tp)> // { dg-error "32:template argument" }
> +struct integral_constant<bool, __is_enum(_Tp)> // { dg-error "not deducible" }
> {
> };
>
> diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic38.C b/gcc/testsuite/g++.dg/cpp0x/variadic38.C
> index b569404cdf2..9155445dce1 100644
> --- a/gcc/testsuite/g++.dg/cpp0x/variadic38.C
> +++ b/gcc/testsuite/g++.dg/cpp0x/variadic38.C
> @@ -3,4 +3,5 @@ template<int... Values>
> struct int_vec {};
>
> template<int... Values>
> -struct int_vec<0, (Values+1)...> {}; // { dg-error "26:template argument" }
> +struct int_vec<0, (Values+1)...> {}; // { dg-error "not deducible" }
> +
> diff --git a/gcc/testsuite/g++.dg/cpp1z/pr81016.C b/gcc/testsuite/g++.dg/cpp1z/pr81016.C
> index 358b12056c0..a17afcc6b65 100644
> --- a/gcc/testsuite/g++.dg/cpp1z/pr81016.C
> +++ b/gcc/testsuite/g++.dg/cpp1z/pr81016.C
> @@ -1,4 +1,4 @@
> // { dg-do compile { target c++17 } }
>
> template <typename a, a> struct b;
> -template <typename c> struct b<bool, c::d>; // { dg-error "template parameter" }
> +template <typename c> struct b<bool, c::d>; // { dg-error "not deducible" }
> diff --git a/gcc/testsuite/g++.dg/template/partial16.C b/gcc/testsuite/g++.dg/template/partial16.C
> new file mode 100644
> index 00000000000..30c34c3e0d9
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/template/partial16.C
> @@ -0,0 +1,8 @@
> +// [temp.spec.partial.general]/9
> +
> +template <class T, T t> struct C {};
> +template <class T> struct C<T, 1>; // { dg-error "depends on a template parameter" }
> +
> +template< int X, int (*array_ptr)[X] > class A {};
> +int array[5];
> +template< int X > class A<X,&array> { }; // { dg-error "depends on a template parameter" }
> diff --git a/gcc/testsuite/g++.dg/template/partial17.C b/gcc/testsuite/g++.dg/template/partial17.C
> new file mode 100644
> index 00000000000..d5c82d26db3
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/template/partial17.C
> @@ -0,0 +1,14 @@
> +// [temp.spec.partial.match]/3
> +
> +template <int I, int J> struct A;
> +template <int I> struct A<I+5, I*2> {}; // { dg-error "not deducible" }
> +
> +template <int I> struct A<I, I> {}; // OK
> +
> +template <int I, int J, int K> struct B;
> +template <int I> struct B<I, I*2, I> {}; // OK
> +template <int I> struct B<I, I*2, 2> { typedef int type; }; // OK
> +
> +B<1, 2, 1> b1;
> +B<1, 2, 2>::type b2;
> +B<1, 2, 3> b3; // { dg-error "incomplete" }
> diff --git a/gcc/testsuite/g++.dg/template/partial18.C b/gcc/testsuite/g++.dg/template/partial18.C
> new file mode 100644
> index 00000000000..7b7614ebc6b
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/template/partial18.C
> @@ -0,0 +1,19 @@
> +// PR c++/96555
> +
> +template<class T, int i>
> +struct X;
> +
> +template<class T>
> +struct X<T, sizeof(T)> {};
> +
> +X<int, sizeof(int)> x1;
> +X<int, sizeof(int)+1> x2; // { dg-error "incomplete" }
> +
> +
> +struct A { int x; } a;
> +template<int, int> struct B;
> +template<int y>
> +struct B<y, sizeof(a.x)> { };
> +
> +B<0, sizeof(int)> b1;
> +B<0, sizeof(int)+1> b2; // { dg-error "incomplete" }
> diff --git a/gcc/testsuite/g++.dg/template/partial5.C b/gcc/testsuite/g++.dg/template/partial5.C
> index 40d8c45b087..037f684cbd2 100644
> --- a/gcc/testsuite/g++.dg/template/partial5.C
> +++ b/gcc/testsuite/g++.dg/template/partial5.C
> @@ -21,4 +21,4 @@ template<typename T, T V>
> struct Z { };
>
> template<typename T>
> -struct Z<T, (T)0> { }; // { dg-error "13:template argument" }
> +struct Z<T, (T)0> { }; // { dg-error "depends on a template parameter" }
> diff --git a/gcc/testsuite/g++.old-deja/g++.pt/spec21.C b/gcc/testsuite/g++.old-deja/g++.pt/spec21.C
> index cf89d6b325a..bf25c0ebb39 100644
> --- a/gcc/testsuite/g++.old-deja/g++.pt/spec21.C
> +++ b/gcc/testsuite/g++.old-deja/g++.pt/spec21.C
> @@ -4,8 +4,7 @@ template <class T> struct S {};
> template <class T = int> struct S<T*> {}; // { dg-error "" } default argument
>
> template <int I, int J> struct A {};
> -template <int I> struct A<I+5, I*2> {}; // { dg-error "28:template argument" }
> -// { dg-error "33:template argument" "" { target *-*-* } .-1 }
> +template <int I> struct A<I+5, I*2> {}; // { dg-error "not deducible" }
> template <class T, T t> struct C {};
> template <class T> struct C<T, 1>; // { dg-error "" } type depends on parameter
> int i;
>
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