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c++: redeclaring member of constrained class template [PR96830]

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An out-of-line definition of a member of a constrained class template
needs to repeat the template's constraints, but it turns out we don't
verify anywhere that the two sets of constraints match.  This patch
adds such a check to push_template_decl, nearby a similar consistency
check for the template parameter list lengths.

	PR c++/96830

gcc/cp/ChangeLog:

	* pt.cc (push_inline_template_parms_recursive): Set
	TEMPLATE_PARMS_CONSTRAINTS.
	(push_template_decl): For an out-of-line declaration, verify
	constraints for each enclosing template scope match those of the
	original template declaratation.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp2a/concepts-class5.C: New test.
	* g++.dg/cpp2a/concepts-class5a.C: New test.
This commit is contained in:
Patrick Palka 2023-03-14 19:14:29 -04:00
parent ec62dc95c4
commit cd5baeb448
3 changed files with 101 additions and 0 deletions
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26
gcc/cp/pt.cc
View file

@ -471,6 +471,8 @@ push_inline_template_parms_recursive (tree parmlist, int levels)
current_template_parms
= tree_cons (size_int (current_template_depth + 1),
parms, current_template_parms);
TEMPLATE_PARMS_CONSTRAINTS (current_template_parms)
= TEMPLATE_PARMS_CONSTRAINTS (parmlist);
TEMPLATE_PARMS_FOR_INLINE (current_template_parms) = 1;
begin_scope (TREE_VEC_LENGTH (parms) ? sk_template_parms : sk_template_spec,
@ -6134,6 +6136,30 @@ push_template_decl (tree decl, bool is_friend)
DECL_INTERFACE_KNOWN (decl) = 1;
return error_mark_node;
}
/* Check that the constraints for each enclosing template scope are
consistent with the original declarations. */
if (flag_concepts)
{
tree decl_parms = DECL_TEMPLATE_PARMS (tmpl);
tree scope_parms = current_template_parms;
if (PRIMARY_TEMPLATE_P (tmpl))
{
decl_parms = TREE_CHAIN (decl_parms);
scope_parms = TREE_CHAIN (scope_parms);
}
while (decl_parms)
{
if (!template_requirements_equivalent_p (decl_parms, scope_parms))
{
error ("redeclaration of %qD with different constraints",
TPARMS_PRIMARY_TEMPLATE (TREE_VALUE (decl_parms)));
break;
}
decl_parms = TREE_CHAIN (decl_parms);
scope_parms = TREE_CHAIN (scope_parms);
}
}
}
gcc_checking_assert (!tmpl || DECL_TEMPLATE_RESULT (tmpl) == decl);

37
gcc/testsuite/g++.dg/cpp2a/concepts-class5.C Normal file
View file

@ -0,0 +1,37 @@
// PR c++/96830
// { dg-do compile { target c++20 } }
template<class T> concept C = true;
template<C T> requires true
struct A {
void f();
template<class U> void g();
struct B;
template<class U> struct C;
static int D;
template<class U> static int E;
};
template<C T>
void A<T>::f() { } // { dg-error "different constraints" }
template<class T> requires true
template<class U>
void A<T>::g() { } // { dg-error "different constraints" }
template<C T> requires (!!true)
struct A<T>::B { }; // { dg-error "different constraints" }
template<class T> requires true
template<class U>
struct A<T>::C { }; // { dg-error "different constraints" }
template<C T>
int A<T>::D = 0; // { dg-error "different constraints" }
template<class T> requires true
template<class U>
int A<T>::E = 0; // { dg-error "different constraints" }

38
gcc/testsuite/g++.dg/cpp2a/concepts-class5a.C Normal file
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@ -0,0 +1,38 @@
// PR c++/96830
// A valid version of concepts-class5.C.
// { dg-do compile { target c++20 } }
template<class T> concept C = true;
template<C T> requires true
struct A {
void f();
template<class U> void g();
struct B;
template<class U> struct C;
static int D;
template<class U> static int E;
};
template<C T> requires true
void A<T>::f() { }
template<C T> requires true
template<class U>
void A<T>::g() { }
template<C T> requires true
struct A<T>::B { };
template<C T> requires true
template<class U>
struct A<T>::C { };
template<C T> requires true
int A<T>::D = 0;
template<C T> requires true
template<class U>
int A<T>::E = 0;