[C++ Patch] PR 88969 ("[9 Regression] ICE in build_op_delete_call, at cp/call.c:6509")

[Paolo Carlini]

Hi,

as far as I can see this ICE on invalid points to a substantive, if 
minor, weakness of our implementation of the destroying operator delete 
facility: we aren't implementing the bits, per 7.6.2.5/(10.1), about 
destroying operator delete having precedence over any other operator 
delete. Thus the below, which is the most straightforward implementation 
I have been able to figure out given the current infrastructure. Tested 
x86_64-linux.

Thanks, Paolo.

////////////////////

/cp
2019-01-24  Paolo Carlini  <paolo.carl...@oracle.com>

        PR c++/88969
        * call.c (build_op_delete_call): Implement 7.6.2.5/(10.1).

/testsuite
2019-01-24  Paolo Carlini  <paolo.carl...@oracle.com>

        PR c++/88969
        * g++.dg/cpp2a/destroying-delete2.C: New.
Index: cp/call.c
===================================================================
--- cp/call.c   (revision 268234)
+++ cp/call.c   (working copy)
@@ -6461,6 +6461,19 @@ build_op_delete_call (enum tree_code code, tree ad
                continue;
              }
 
+           /* -- If any of the deallocation functions is a destroying
+              operator delete, all deallocation functions that are not
+              destroying operator deletes are eliminated from further
+              consideration.  */
+           bool fn_destroying = destroying_delete_p (fn);
+           bool elt_destroying = destroying_delete_p (elt);
+           if (elt_destroying != fn_destroying)
+             {
+               if (elt_destroying)
+                 fn = elt;
+               continue;
+             }
+
            /* -- If the type has new-extended alignment, a function with a
               parameter of type std::align_val_t is preferred; otherwise a
               function without such a parameter is preferred. If exactly one
Index: testsuite/g++.dg/cpp2a/destroying-delete2.C
===================================================================
--- testsuite/g++.dg/cpp2a/destroying-delete2.C (nonexistent)
+++ testsuite/g++.dg/cpp2a/destroying-delete2.C (working copy)
@@ -0,0 +1,20 @@
+// PR c++/88969
+// { dg-do compile { target c++2a } }
+
+#include <new>
+
+namespace delete_selection_d {
+  struct B {
+    void operator delete(void*) = delete;
+    void operator delete(B *, std::destroying_delete_t) = delete;  // { 
dg-message "declared here" }
+  };
+  void delete_B(B *b) { delete b; }  // { dg-error "use of deleted function" }
+}
+
+namespace delete_selection_r {
+  struct B {
+    void operator delete(B *, std::destroying_delete_t) = delete;  // { 
dg-message "declared here" }
+    void operator delete(void*) = delete;
+  };
+  void delete_B(B *b) { delete b; }  // { dg-error "use of deleted function" }
+}