[pushed] c++: throwing cleanup after return [PR113347]

[Jason Merrill]

Tested x86_64-pc-linux-gnu, applying to 12/13.

-- 8< --

Here we were assuming that current_retval_sentinel would be set if we have
seen a throwing cleanup, but that's not the case if the cleanup is after all
returns.

This change isn't needed on trunk, where current_retval_sentinel is set for
all NRV functions.

        PR c++/113347

gcc/cp/ChangeLog:

        * semantics.cc (finalize_nrv_r): Handle null
        current_retval_sentinel.

gcc/testsuite/ChangeLog:

        * g++.dg/eh/return3.C: New test.
---
 gcc/cp/semantics.cc               |  3 ++-
 gcc/testsuite/g++.dg/eh/return3.C | 17 +++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/eh/return3.C

diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 02838775003..ff5252905fe 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -4953,7 +4953,8 @@ finalize_nrv_r (tree* tp, int* walk_subtrees, void* data)
       /* If a cleanup might throw, we need to clear current_retval_sentinel on
         the exception path so an outer cleanup added by
         maybe_splice_retval_cleanup doesn't run.  */
-      if (cp_function_chain->throwing_cleanup)
+      if (current_retval_sentinel
+         && cp_function_chain->throwing_cleanup)
        {
          tree clear = build2 (MODIFY_EXPR, boolean_type_node,
                               current_retval_sentinel,
diff --git a/gcc/testsuite/g++.dg/eh/return3.C 
b/gcc/testsuite/g++.dg/eh/return3.C
new file mode 100644
index 00000000000..76aa50d523d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/eh/return3.C
@@ -0,0 +1,17 @@
+// PR c++/113347
+
+#if __cplusplus < 201103L
+#define THROWS
+#else
+#define THROWS noexcept(false)
+#endif
+
+struct A { ~A(); };
+struct B { ~B() THROWS; };
+
+A f()
+{
+  A a;
+  return a;
+  B();
+}

base-commit: 46874833290ee5fcd94c6e184fcd51fcd2c74e28
-- 
2.39.3