On 6/9/23 11:19, Patrick Palka wrote:
When defining a previously declared class template, we neglect to set
TPARMS_PRIMARY_TEMPLATE for the in-scope template parameters, which the
class members go on to inherit, and so the members' DECL_TEMPLATE_PARMS
will have empty TPARMS_PRIMARY_TEMPLATE at those levels as well. This
causes us to crash when diagnosing a constraint mismatch for an
out-of-line declaration of a member of a constrained class template.
This patch fixes this by walking the context to get at the corresponding
primary template instead. I spent a while trying to get us to set
TPARMS_PRIMARY_TEMPLATE for templated class definitions that are
redeclarations, but it proved to be hairy in particular for partial
specializations and nested templates.
Maybe set it a bit earlier in push_template_decl, if you're going to
figure out here what it should be anyway?
Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk/13?
PR c++/109655
gcc/cp/ChangeLog:
* pt.cc (push_template_decl): Handle TPARMS_PRIMARY_TEMPLATE
being empty when diagnosing a constraint mismatch for an
enclosing template scope. Don't bother checking constraints
if DECL_PARMS and SCOPE_PARMS are the same.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/concepts-class6.C: New test.
* g++.dg/cpp2a/concepts-class6a.C: New test.
---
gcc/cp/pt.cc | 19 +++++++--
gcc/testsuite/g++.dg/cpp2a/concepts-class6.C | 30 ++++++++++++++
gcc/testsuite/g++.dg/cpp2a/concepts-class6a.C | 40 +++++++++++++++++++
3 files changed, 86 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-class6.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-class6a.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 17bf4d24151..f913b248345 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -6155,12 +6155,25 @@ push_template_decl (tree decl, bool is_friend)
decl_parms = TREE_CHAIN (decl_parms);
scope_parms = TREE_CHAIN (scope_parms);
}
- while (decl_parms)
+ while (decl_parms && decl_parms != scope_parms)
{
if (!template_requirements_equivalent_p (decl_parms, scope_parms))
{
- error ("redeclaration of %qD with different constraints",
- TPARMS_PRIMARY_TEMPLATE (TREE_VALUE (decl_parms)));
+ tree td = TPARMS_PRIMARY_TEMPLATE (TREE_VALUE (decl_parms));
+ if (!td)
+ {
+ /* FIXME: TPARMS_PRIMARY_TEMPLATE doesn't always get
+ set for enclosing template scopes. Work around
+ this by walking the context to obtain the relevant
+ (primary) template whose constraints we mismatch. */
+ int level = TMPL_PARMS_DEPTH (decl_parms);
+ td = TYPE_TI_TEMPLATE (ctx);
+ while (!PRIMARY_TEMPLATE_P (td)
+ || (TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (td))
+ != level))
+ td = TYPE_TI_TEMPLATE (DECL_CONTEXT (td));
+ }
+ error ("redeclaration of %qD with different constraints", td);
break;
}
decl_parms = TREE_CHAIN (decl_parms);
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-class6.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-class6.C
new file mode 100644
index 00000000000..dcef6a2c9d4
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-class6.C
@@ -0,0 +1,30 @@
+// PR c++/109655
+// { dg-do compile { target c++20 } }
+
+class C {
+ template<class>
+ requires true
+ friend class D;
+
+ template<class>
+ requires true
+ class E;
+};
+
+template<class>
+requires true
+class D {
+ void f();
+};
+
+template<class T>
+void D<T>::f() { } // { dg-error "class D' with different constraints" }
+
+template<class>
+requires true
+class C::E {
+ void f();
+};
+
+template<class T>
+void C::E<T>::f() { } // { dg-error "class C::E' with different constraints" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-class6a.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-class6a.C
new file mode 100644
index 00000000000..751d13cdf6c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-class6a.C
@@ -0,0 +1,40 @@
+// PR c++/109655
+// { dg-do compile { target c++20 } }
+
+template<class T>
+requires true
+class C {
+ class D;
+
+ template<class>
+ requires (!!true)
+ class E;
+};
+
+template<class T>
+requires true
+class C<T>::D {
+ void f();
+};
+
+template<class T> // missing "requires true"
+void C<T>::D::f() { } // { dg-error "class C' with different constraints" }
+
+template<class T>
+requires true
+template<class U>
+requires (!!true)
+class C<T>::E {
+ void f();
+ void g();
+};
+
+template<class T>
+requires true
+template<class U>
+void C<T>::E<U>::f() { } // { dg-error "class C<T>::E' with different
constraints" }
+
+template<class T>
+template<class U>
+requires (!!true)
+void C<T>::E<U>::g() { } // { dg-error "class C' with different constraints" }
