[pushed] c++: local class in nested generic lambda [PR109241]

[pushed] c++: local class in nested generic lambda [PR109241]

[Jason Merrill]

Tested x86_64-pc-linux-gnu, applying to trunk.

-- 8< --

In this testcase, the tree walk to look for bare parameter packs was
confused by finding a type with no TREE_BINFO.  But it should be fine that
it's unset; we already checked for unexpanded packs at parse time.

I also tried doing the partial instantiation of the local class, which is
probably the long-term direction we want to go, but for stage 4 let's go
with this safer change.

	PR c++/109241

gcc/cp/ChangeLog:

	* pt.cc (find_parameter_packs_r): Handle null TREE_BINFO.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp1y/lambda-generic-local-class2.C: New test.
---
 gcc/cp/pt.cc                                        | 12 ++++++++----
 .../g++.dg/cpp1y/lambda-generic-local-class2.C      | 13 +++++++++++++
 2 files changed, 21 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp1y/lambda-generic-local-class2.C

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 90bcaa78701..40deedc9ba9 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -4069,10 +4069,14 @@ find_parameter_packs_r (tree *tp, int *walk_subtrees, void* data)
     case TAG_DEFN:
       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);
+	{
+	  /* Local class, need to look through the whole definition.
+	     TYPE_BINFO might be unset for a partial instantiation.  */
+	  if (TYPE_BINFO (t))
+	    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))
diff --git a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-local-class2.C b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-local-class2.C
new file mode 100644
index 00000000000..83856de1f41
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-local-class2.C
@@ -0,0 +1,13 @@
+// PR c++/109241
+// { dg-do compile { target c++14 } }
+// { dg-options "" } no pedantic
+
+void g() {
+  [](auto) {
+    [](auto) {
+      ({
+        struct A {};
+      });
+    };
+  }(1);
+}

base-commit: cd0c433e5faba9a18f64881cd761a53a530aa798
-- 
2.31.1

[pushed] c++: local class in nested generic lambda [PR109241]

[Jason Merrill]

Tested x86_64-pc-linux-gnu, applying to trunk.

-- 8< --

The earlier fix for PR109241 avoided the crash by handling a type with no
TREE_BINFO.  But we want to move toward doing the partial substitution of
classes in generic lambdas, so let's take a step in that direction.

	PR c++/109241

gcc/cp/ChangeLog:

	* pt.cc (instantiate_class_template): Do partially instantiate.
	(tsubst_expr): Do call complete_type for partial instantiations.
---
 gcc/cp/pt.cc | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index e1c272b9817..93a055c66a1 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -12086,7 +12086,8 @@ instantiate_class_template (tree type)
     return error_mark_node;
 
   if (COMPLETE_OR_OPEN_TYPE_P (type)
-      || uses_template_parms (type))
+      || (uses_template_parms (type)
+	  && !TYPE_FUNCTION_SCOPE_P (type)))
     return type;
 
   /* Figure out which template is being instantiated.  */
@@ -19356,10 +19357,7 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 
     case TAG_DEFN:
       tmp = tsubst (TREE_TYPE (t), args, complain, NULL_TREE);
-      if (dependent_type_p (tmp))
-	/* This is a partial instantiation, try again when full.  */
-	add_stmt (build_min (TAG_DEFN, tmp));
-      else if (CLASS_TYPE_P (tmp))
+      if (CLASS_TYPE_P (tmp))
 	{
 	  /* Local classes are not independent templates; they are
 	     instantiated along with their containing function.  And this
@@ -19368,6 +19366,12 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 	  /* Closures are handled by the LAMBDA_EXPR.  */
 	  gcc_assert (!LAMBDA_TYPE_P (TREE_TYPE (t)));
 	  complete_type (tmp);
+	  if (dependent_type_p (tmp))
+	    {
+	      /* This is a partial instantiation, try again when full.  */
+	      add_stmt (build_min (TAG_DEFN, tmp));
+	      break;
+	    }
 	  tree save_ccp = current_class_ptr;
 	  tree save_ccr = current_class_ref;
 	  for (tree fld = TYPE_FIELDS (tmp); fld; fld = DECL_CHAIN (fld))

base-commit: 50d866038a910ceb9075b97295a12d77a8d09a3a
prerequisite-patch-id: 4ed1b4e9cbee2ce090bd119cbf47056c35aaeb57
prerequisite-patch-id: cd3a881f1b6cd3bca0064002d9a96f2f52c85a79
-- 
2.31.1