[gcc r12-10110] c++: throwing dtor and empty try [PR113088]

[Jason Merrill <jason@gcc.gnu.org>]

https://gcc.gnu.org/g:b0605cd4a12e9162cc56abc69ca1048947c72689

commit r12-10110-gb0605cd4a12e9162cc56abc69ca1048947c72689
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Dec 20 11:06:27 2023 -0500

    c++: throwing dtor and empty try [PR113088]
    
    maybe_splice_retval_cleanup assumed that the function body can't be empty if
    there's a throwing cleanup, but when I added cleanups to try blocks in
    r12-6333-gb10e031458d541 I didn't adjust that assumption.
    
            PR c++/113088
            PR c++/33799
    
    gcc/cp/ChangeLog:
    
            * except.cc (maybe_splice_retval_cleanup): Handle an empty block.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/eh/return2.C: New test.
    
    (cherry picked from commit 02c0b49798228d777610f898cd9d63ebec43656d)

Diff:
---
 gcc/cp/except.cc                  |  8 ++++++--
 gcc/testsuite/g++.dg/eh/return2.C | 26 ++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/gcc/cp/except.cc b/gcc/cp/except.cc
index b9f49d1bfc6..96e19b18a71 100644
--- a/gcc/cp/except.cc
+++ b/gcc/cp/except.cc
@@ -1345,9 +1345,13 @@ maybe_splice_retval_cleanup (tree compound_stmt, bool is_try)
 	}
 
       /* Skip past other decls, they can't contain a return.  */
-      while (TREE_CODE (tsi_stmt (iter)) == DECL_EXPR)
+      while (!tsi_end_p (iter)
+	     && TREE_CODE (tsi_stmt (iter)) == DECL_EXPR)
 	tsi_next (&iter);
-      gcc_assert (!tsi_end_p (iter));
+
+      if (tsi_end_p (iter))
+	/* Nothing to wrap.  */
+	return;
 
       /* Wrap the rest of the STATEMENT_LIST in a CLEANUP_STMT.  */
       tree stmts = NULL_TREE;
diff --git a/gcc/testsuite/g++.dg/eh/return2.C b/gcc/testsuite/g++.dg/eh/return2.C
new file mode 100644
index 00000000000..b467d7494af
--- /dev/null
+++ b/gcc/testsuite/g++.dg/eh/return2.C
@@ -0,0 +1,26 @@
+// PR c++/113088
+
+#if __cplusplus >= 201103L
+#define THROWS noexcept(false)
+#else
+#define THROWS
+#endif
+
+struct X {
+  ~X() {}
+};
+
+struct Y {
+  ~Y() THROWS {}
+};
+
+X foo() {
+  try {
+    return X();
+  } catch (...) {
+    Y();
+    return X();
+  }
+
+  try { } catch (...) { }
+}