c++: SFINAE for invalid delete-expression [PR79706]

This fixes SFINAE when substitution yields an invalid delete-expression
due to the pertinent deallocation function being marked deleted or
otherwise inaccessible.

We need to check for an erroneous result from build_op_delete_call and
exit early in that case, so that we don't build a COND_EXPR around the
erroneous result which finish_decltype_type would then quietly accept.

gcc/cp/ChangeLog:

	PR c++/79706
	* init.c (build_vec_delete_1): Just return error_mark_node if
	deallocate_expr is error_mark_node.
	(build_delete): Just return error_mark_node if do_delete is
	error_mark_node.

gcc/testsuite/ChangeLog:

	PR c++/79706
	* g++.dg/template/sfinae30.C: New test.

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 73a6500..a45657d 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,13 @@
 2020-05-13  Patrick Palka  <ppalka@redhat.com>
 
+       PR c++/79706
+       * init.c (build_vec_delete_1): Just return error_mark_node if
+       deallocate_expr is error_mark_node.
+       (build_delete): Just return error_mark_node if do_delete is
+       error_mark_node.
+
+2020-05-13  Patrick Palka  <ppalka@redhat.com>
+
        PR c++/95020
        * constraint.c (tsubst_requires_expr): Produce a new
        requires-expression when processing_template_decl, even if

diff --git a/gcc/cp/init.c b/gcc/cp/init.c
index 56715d6..d4c883b 100644 (file)
--- a/gcc/cp/init.c
+++ b/gcc/cp/init.c
@@ -4076,7 +4076,9 @@ build_vec_delete_1 (location_t loc, tree base, tree maxindex, tree type,
     }
 
   body = loop;
-  if (!deallocate_expr)
+  if (deallocate_expr == error_mark_node)
+    return error_mark_node;
+  else if (!deallocate_expr)
     ;
   else if (!body)
     body = deallocate_expr;
@@ -4993,7 +4995,9 @@ build_delete (location_t loc, tree otype, tree addr,
       return expr;
     }
 
-  if (do_delete)
+  if (do_delete == error_mark_node)
+    return error_mark_node;
+  else if (do_delete)
     {
       tree do_delete_call_expr = extract_call_expr (do_delete);
       if (TREE_CODE (do_delete_call_expr) == CALL_EXPR)

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b88e182..858fd64 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,10 @@
 2020-05-13  Patrick Palka  <ppalka@redhat.com>
 
+       PR c++/79706
+       * g++.dg/template/sfinae30.C: New test.
+
+2020-05-13  Patrick Palka  <ppalka@redhat.com>
+
        PR c++/95020
        * g++/cpp2a/concepts-lambda7.C: New test.
 

diff --git a/gcc/testsuite/g++.dg/template/sfinae30.C b/gcc/testsuite/g++.dg/template/sfinae30.C
new file mode 100644 (file)
index 0000000..82f31aa
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/sfinae30.C
@@ -0,0 +1,21 @@
+// PR c++/79706
+// { dg-do compile { target c++11 } }
+
+struct A {
+  void operator delete(void*) = delete;
+private:
+  void operator delete[](void*);
+};
+
+extern A *p;
+
+template<typename T>
+auto foo(T *t) -> decltype(delete t); // { dg-error "use of deleted function" }
+
+template<typename T>
+auto bar(T *t) -> decltype(delete[] t); // { dg-error "private within this context" }
+
+void baz() {
+  foo<A>(p); // { dg-error "no match" }
+  bar<A>(p); // { dg-error "no match" }
+}