[PATCH] tree-eh: Don't crash on GIMPLE_TRY_FINALLY with empty cleanup sequence [PR117845]

[Simon Martin]

The following valid code triggers an ICE with -fsanitize=address

=== cut here ===
void l() {
    auto const ints = {0,1,2,3,4,5};
    for (auto i : { 3 } ) {
        __builtin_printf("%d ", i);
    }
}
=== cut here ===

The problem is that honor_protect_cleanup_actions does not expect the
cleanup sequence of a GIMPLE_TRY_FINALLY to be empty. It is however the
case here since r14-8681-gceb242f5302027, because lower_stmt removes the
only statement in the sequence: a ASAN_MARK statement for the array that
backs the initializer_list).

This patch simply checks that the finally block is not 0 before
accessing it in honor_protect_cleanup_actions.

Successfully tested on x86_64-pc-linux-gnu. OK for trunk and gcc-14?

        PR c++/117845

gcc/ChangeLog:

        * tree-eh.cc (honor_protect_cleanup_actions): Support empty
        finally sequences.

gcc/testsuite/ChangeLog:

        * g++.dg/asan/pr117845-2.C: New test.
        * g++.dg/asan/pr117845.C: New test.

---
 gcc/testsuite/g++.dg/asan/pr117845-2.C | 12 ++++++++++++
 gcc/testsuite/g++.dg/asan/pr117845.C   | 12 ++++++++++++
 gcc/tree-eh.cc                         |  3 ++-
 3 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/asan/pr117845-2.C
 create mode 100644 gcc/testsuite/g++.dg/asan/pr117845.C

diff --git a/gcc/testsuite/g++.dg/asan/pr117845-2.C 
b/gcc/testsuite/g++.dg/asan/pr117845-2.C
new file mode 100644
index 00000000000..c0556397009
--- /dev/null
+++ b/gcc/testsuite/g++.dg/asan/pr117845-2.C
@@ -0,0 +1,12 @@
+// PR c++/117845 - Actually valid variant
+// { dg-do "compile" }
+// { dg-options "-fsanitize=address" }
+
+#include <initializer_list>
+
+void l() {
+    auto const ints = {0,1,2,3,4,5};
+    for (auto i : { 3 } ) {
+        __builtin_printf("%d ", i);
+    }
+}
diff --git a/gcc/testsuite/g++.dg/asan/pr117845.C 
b/gcc/testsuite/g++.dg/asan/pr117845.C
new file mode 100644
index 00000000000..d90d351e270
--- /dev/null
+++ b/gcc/testsuite/g++.dg/asan/pr117845.C
@@ -0,0 +1,12 @@
+// PR c++/117845 - Initially reported case.
+// { dg-do "compile" }
+// { dg-options "-fsanitize=address" }
+
+#include <initializer_list>
+
+void l() {
+    auto const ints = {0,1,2,3,4,5};
+    for (int i : ints | h) { // { dg-error "was not declared" }
+        __builtin_printf("%d ", i);
+    }
+}
diff --git a/gcc/tree-eh.cc b/gcc/tree-eh.cc
index 769785fad2b..dc920de9b38 100644
--- a/gcc/tree-eh.cc
+++ b/gcc/tree-eh.cc
@@ -1026,7 +1026,8 @@ honor_protect_cleanup_actions (struct leh_state 
*outer_state,
         MUST_NOT_THROW filter.  */
       gimple_stmt_iterator gsi = gsi_start (finally);
       gimple *x = gsi_stmt (gsi);
-      if (gimple_code (x) == GIMPLE_TRY
+      if (x
+         && gimple_code (x) == GIMPLE_TRY
          && gimple_try_kind (x) == GIMPLE_TRY_CATCH
          && gimple_try_catch_is_cleanup (x))
        {
-- 
2.44.0