[gcc r12-10519] c++: Fix ICE with weird copy assignment operator [PR114572]

[Jakub Jelinek]

https://gcc.gnu.org/g:f33e8ee4cb44e7a6326a894a9c153557238bde03

commit r12-10519-gf33e8ee4cb44e7a6326a894a9c153557238bde03
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Apr 5 09:31:28 2024 +0200

    c++: Fix ICE with weird copy assignment operator [PR114572]
    
    While ctors/dtors don't return anything (undeclared void or this pointer
    on arm) and copy assignment operators normally return a reference to *this,
    it isn't invalid to return uselessly some class object which might need
    destructing, but the OpenMP clause handling code wasn't expecting that.
    
    The following patch fixes that.
    
    2024-04-05  Jakub Jelinek  <jakub@redhat.com>
    
            PR c++/114572
            * cp-gimplify.cc (cxx_omp_clause_apply_fn): Call build_cplus_new
            on build_call_a result if it has class type.
    
            * testsuite/libgomp.c++/pr114572.C: New test.
    
    (cherry picked from commit 592536eb3c0a97a55b1019ff0216ef77e6ca847e)

Diff:
---
 gcc/cp/cp-gimplify.cc                    |  4 ++++
 libgomp/testsuite/libgomp.c++/pr114572.C | 24 ++++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
index 7ae5327f693..4b7e5729ef1 100644
--- a/gcc/cp/cp-gimplify.cc
+++ b/gcc/cp/cp-gimplify.cc
@@ -2038,6 +2038,8 @@ cxx_omp_clause_apply_fn (tree fn, tree arg1, tree arg2)
 					   TREE_PURPOSE (parm), fn,
 					   i - is_method, tf_warning_or_error);
       t = build_call_a (fn, i, argarray);
+      if (MAYBE_CLASS_TYPE_P (TREE_TYPE (t)))
+	t = build_cplus_new (TREE_TYPE (t), t, tf_warning_or_error);
       t = fold_convert (void_type_node, t);
       t = fold_build_cleanup_point_expr (TREE_TYPE (t), t);
       append_to_statement_list (t, &ret);
@@ -2071,6 +2073,8 @@ cxx_omp_clause_apply_fn (tree fn, tree arg1, tree arg2)
 					   TREE_PURPOSE (parm), fn,
 					   i - is_method, tf_warning_or_error);
       t = build_call_a (fn, i, argarray);
+      if (MAYBE_CLASS_TYPE_P (TREE_TYPE (t)))
+	t = build_cplus_new (TREE_TYPE (t), t, tf_warning_or_error);
       t = fold_convert (void_type_node, t);
       return fold_build_cleanup_point_expr (TREE_TYPE (t), t);
     }
diff --git a/libgomp/testsuite/libgomp.c++/pr114572.C b/libgomp/testsuite/libgomp.c++/pr114572.C
new file mode 100644
index 00000000000..21d5c847f8d
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c++/pr114572.C
@@ -0,0 +1,24 @@
+// PR c++/114572
+// { dg-do run }
+// { dg-options "-fopenmp -O0" }
+
+#include <stdlib.h>
+
+struct S
+{
+  S () : s (0) {}
+  ~S () {}
+  S operator= (const S &x) { s = x.s; return *this; }
+  int s;
+};
+
+int
+main ()
+{
+  S s;
+  #pragma omp parallel for lastprivate(s)
+  for (int i = 0; i < 10; ++i)
+    s.s = i;
+  if (s.s != 9)
+    abort ();
+}