[gcc r14-10221] c++: aggregate CTAD w/ paren init and bases [PR115114]

[Patrick Palka via Gcc-cvs]

https://gcc.gnu.org/g:a9837934203d41c96b5cf05e34f68c0d3311c973

commit r14-10221-ga9837934203d41c96b5cf05e34f68c0d3311c973
Author: Patrick Palka <ppa...@redhat.com>
Date:   Fri May 17 09:02:52 2024 -0400

    c++: aggregate CTAD w/ paren init and bases [PR115114]
    
    During aggregate CTAD with paren init, we're accidentally overlooking
    base classes since TYPE_FIELDS of a template type doesn't contain
    corresponding base fields.  So we need to consider them separately.
    
            PR c++/115114
    
    gcc/cp/ChangeLog:
    
            * pt.cc (maybe_aggr_guide): Consider bases in the paren init case.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/cpp2a/class-deduction-aggr15.C: New test.
    
    Reviewed-by: Jason Merrill <ja...@redhat.com>
    (cherry picked from commit 5aaf47cb1987bbc5508c4b9b7dad5ea7d69af2c2)

Diff:
---
 gcc/cp/pt.cc                                       |  7 +++++++
 .../g++.dg/cpp2a/class-deduction-aggr15.C          | 23 ++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index b5c494e8d15e..e9882f2a3e0a 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -30205,6 +30205,13 @@ maybe_aggr_guide (tree tmpl, tree init, 
vec<tree,va_gc> *args)
   else if (TREE_CODE (init) == TREE_LIST)
     {
       int len = list_length (init);
+      for (tree binfo : BINFO_BASE_BINFOS (TYPE_BINFO (template_type)))
+       {
+         if (!len)
+           break;
+         parms = tree_cons (NULL_TREE, BINFO_TYPE (binfo), parms);
+         --len;
+       }
       for (tree field = TYPE_FIELDS (template_type);
           len;
           --len, field = DECL_CHAIN (field))
diff --git a/gcc/testsuite/g++.dg/cpp2a/class-deduction-aggr15.C 
b/gcc/testsuite/g++.dg/cpp2a/class-deduction-aggr15.C
new file mode 100644
index 000000000000..16dc0f52b64c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/class-deduction-aggr15.C
@@ -0,0 +1,23 @@
+// PR c++/115114
+// { dg-do compile { target c++20 } }
+
+struct X {} x;
+struct Y {} y;
+
+template<class T, class U>
+struct A : T {
+  U m;
+};
+
+using ty1 = decltype(A{x, 42}); // OK
+using ty1 = decltype(A(x, 42)); // OK, used to fail
+using ty1 = A<X, int>;
+
+template<class T, class U = int, class V = int>
+struct B : T, V {
+  U m = 42;
+};
+
+using ty2 = decltype(B{x, y}); // OK
+using ty2 = decltype(B(x, y)); // OK, used to fail
+using ty2 = B<X, int, Y>;