On 3/14/23 12:41, Patrick Palka wrote:
When redeclaring a member of a constrained class template, we need to
repeat the class's constraints, but it turns out we don't verify
anywhere that the repeated constraints match the class's constraints.
A safe place to do so seems to be in push_template_decl, nearby a
similar consistency check for the template parameter list length of a
redeclaration.
Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk/12?
Both patches are OK for trunk, but not 12; we tend not to backport fixes
for accepts-invalid bugs, especially if they aren't regressions. We
don't want to add new diagnostics to an active release branch.
PR c++/96830
gcc/cp/ChangeLog:
* pt.cc (push_inline_template_parms_recursive): Set
TEMPLATE_PARMS_CONSTRAINTS.
(push_template_decl): For a redeclaration, 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.
---
gcc/cp/pt.cc | 26 +++++++++++++
gcc/testsuite/g++.dg/cpp2a/concepts-class5.C | 37 ++++++++++++++++++
gcc/testsuite/g++.dg/cpp2a/concepts-class5a.C | 38 +++++++++++++++++++
3 files changed, 101 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-class5.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-class5a.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 053cc52b285..370a4f70f08 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -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 template declaration. */
+ 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);
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-class5.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-class5.C
new file mode 100644
index 00000000000..5d893d9f6a7
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-class5.C
@@ -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" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-class5a.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-class5a.C
new file mode 100644
index 00000000000..a6a3684c258
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-class5a.C
@@ -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;
