[gcc r12-7] c++: unexpanded pack in enum in lambda [PR100109]

[gcc r12-7] c++: unexpanded pack in enum in lambda [PR100109]

[Jason Merrill]

https://gcc.gnu.org/g:7f5deba1c21888aacedae93e9f324827073a1d1e

commit r12-7-g7f5deba1c21888aacedae93e9f324827073a1d1e
Author: Jason Merrill <jason@redhat.com>
Date:   Tue Apr 20 00:50:49 2021 -0400

    c++: unexpanded pack in enum in lambda [PR100109]
    
    Another construct we need to look inside.
    
    gcc/cp/ChangeLog:
    
            PR c++/100109
            * pt.c (find_parameter_packs_r): Look into enum initializers.
    
    gcc/testsuite/ChangeLog:
    
            PR c++/100109
            * g++.dg/cpp0x/lambda/lambda-variadic14.C: New test.

Diff:
---
 gcc/cp/pt.c                                           | 8 +++++++-
 gcc/testsuite/g++.dg/cpp0x/lambda/lambda-variadic14.C | 8 ++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 19fdafa4c43..7bcbe6dc3ce 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -4066,12 +4066,18 @@ find_parameter_packs_r (tree *tp, int *walk_subtrees, void* data)
       return NULL_TREE;
 
     case TAG_DEFN:
-      /* Local class, need to look through the whole definition.  */
       t = TREE_TYPE (t);
       if (CLASS_TYPE_P (t))
+	/* Local class, need to look through the whole definition.  */
 	for (tree bb : BINFO_BASE_BINFOS (TYPE_BINFO (t)))
 	  cp_walk_tree (&BINFO_TYPE (bb), &find_parameter_packs_r,
 			ppd, ppd->visited);
+      else
+	/* Enum, look at the values.  */
+	for (tree l = TYPE_VALUES (t); l; l = TREE_CHAIN (l))
+	  cp_walk_tree (&DECL_INITIAL (TREE_VALUE (l)),
+			&find_parameter_packs_r,
+			ppd, ppd->visited);
       return NULL_TREE;
 
     case FUNCTION_TYPE:
diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-variadic14.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-variadic14.C
new file mode 100644
index 00000000000..185aa0332e7
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-variadic14.C
@@ -0,0 +1,8 @@
+// PR c++/100109
+// { dg-do compile { target c++11 } }
+
+template <int... E>
+void f() {
+  [] { enum e { e = E }; };	// { dg-error "not expanded" }
+}
+template void f<>();