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* [gcc r12-1093] c++: Relax rule for non-type arguments in partial specs [CWG1315]
@ 2021-05-27 16:37 Patrick Palka
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From: Patrick Palka @ 2021-05-27 16:37 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:9b94785dedb08b006419bec1a402614d9241317a
commit r12-1093-g9b94785dedb08b006419bec1a402614d9241317a
Author: Patrick Palka <ppalka@redhat.com>
Date: Thu May 27 12:36:39 2021 -0400
c++: Relax rule for non-type arguments in partial specs [CWG1315]
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 single check from process_partial_specialization (amidst
a bunch of whitespace changes).
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 relaxed). For now this patch makes a minimal
amount of changes to for_each_template_parm_r so that we continue to
reject existing ill-formed partial specializations within the testsuite.
I opened PR c++/100779 to track this issue.
DR 1315
PR c++/67593
PR c++/96555
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 false.
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/template/partial19.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.
Diff:
---
gcc/cp/pt.c | 122 ++++++++++++++---------------
gcc/testsuite/g++.dg/cpp0x/pr68724.C | 2 +-
gcc/testsuite/g++.dg/cpp0x/variadic38.C | 2 +-
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/partial19.C | 11 +++
gcc/testsuite/g++.dg/template/partial5.C | 2 +-
gcc/testsuite/g++.old-deja/g++.pt/spec21.C | 3 +-
10 files changed, 114 insertions(+), 71 deletions(-)
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index f3fa9c192ad..e4950aa448a 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
@@ -5222,63 +5218,55 @@ process_partial_specialization (tree decl)
|| 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
- upon. */
- tree type = TREE_TYPE (parm);
+ /* Look at the corresponding template parameter,
+ marking which template parameters its type depends
+ upon. */
+ tree type = TREE_TYPE (parm);
- if (!tpd2.parms)
- {
- /* We haven't yet initialized TPD2. Do so now. */
- tpd2.arg_uses_template_parms = XALLOCAVEC (int, nargs);
- /* The number of parameters here is the number in the
- main template, which, as checked in the assertion
- above, is NARGS. */
- tpd2.parms = XALLOCAVEC (int, nargs);
- tpd2.level =
- TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (maintmpl));
- }
+ if (!tpd2.parms)
+ {
+ /* We haven't yet initialized TPD2. Do so now. */
+ tpd2.arg_uses_template_parms = XALLOCAVEC (int, nargs);
+ /* The number of parameters here is the number in the
+ main template, which, as checked in the assertion
+ above, is NARGS. */
+ tpd2.parms = XALLOCAVEC (int, nargs);
+ tpd2.level =
+ TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (maintmpl));
+ }
- /* Mark the template parameters. But this time, we're
- looking for the template parameters of the main
- template, not in the specialization. */
- tpd2.current_arg = i;
- tpd2.arg_uses_template_parms[i] = 0;
- memset (tpd2.parms, 0, sizeof (int) * nargs);
- for_each_template_parm (type,
- &mark_template_parm,
- &tpd2,
- NULL,
- /*include_nondeduced_p=*/false);
-
- if (tpd2.arg_uses_template_parms [i])
- {
- /* The type depended on some template parameters.
- If they are fully specialized in the
- specialization, that's OK. */
- int j;
- int count = 0;
- for (j = 0; j < nargs; ++j)
- if (tpd2.parms[j] != 0
- && tpd.arg_uses_template_parms [j])
- ++count;
- if (count != 0)
- error_n (input_location, count,
- "type %qT of template argument %qE depends "
- "on a template parameter",
- "type %qT of template argument %qE depends "
- "on template parameters",
- type,
- arg);
- }
- }
+ /* Mark the template parameters. But this time, we're
+ looking for the template parameters of the main
+ template, not in the specialization. */
+ tpd2.current_arg = i;
+ tpd2.arg_uses_template_parms[i] = 0;
+ memset (tpd2.parms, 0, sizeof (int) * nargs);
+ for_each_template_parm (type,
+ &mark_template_parm,
+ &tpd2,
+ NULL,
+ /*include_nondeduced_p=*/false);
+
+ if (tpd2.arg_uses_template_parms [i])
+ {
+ /* The type depended on some template parameters.
+ If they are fully specialized in the
+ specialization, that's OK. */
+ int j;
+ int count = 0;
+ for (j = 0; j < nargs; ++j)
+ if (tpd2.parms[j] != 0
+ && tpd.arg_uses_template_parms [j])
+ ++count;
+ if (count != 0)
+ error_n (input_location, count,
+ "type %qT of template argument %qE depends "
+ "on a template parameter",
+ "type %qT of template argument %qE depends "
+ "on template parameters",
+ type,
+ arg);
+ }
}
}
}
@@ -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 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..49fa48c3bd2 100644
--- a/gcc/testsuite/g++.dg/cpp0x/variadic38.C
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic38.C
@@ -3,4 +3,4 @@ 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/partial19.C b/gcc/testsuite/g++.dg/template/partial19.C
new file mode 100644
index 00000000000..39149d220b4
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/partial19.C
@@ -0,0 +1,11 @@
+// PR c++/67593
+// { dg-do compile { target c++11 } }
+
+template<class T>
+struct outer {
+ template<T...> struct inner;
+ template<T... Vs> struct inner<T{}, Vs...> {};
+};
+
+outer<int>::inner<0, 0> x1;
+outer<int>::inner<1, 0> x2; // { 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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