Hi!
The assert there assumes we never evaluate a statement list to
DEBUG_BEGIN_STMT, but it breaks appart when a BIND_EXPR with a typedef in it
has some DEBUG_BEGIN_STMTs in it and nothing else (without -g it is just
empty STATEMENT_LIST inside of the BIND_EXPR). We want to return void_node
in that case.
THere is nothing interesting about DEBUG_BEGIN_STMT for constexpr
evaluation, it doesn't change any values, so let's just ignore them
and the assert is then unnecessary.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2018-01-09 Jakub Jelinek <ja...@redhat.com>
PR c++/83734
* constexpr.c (cxx_eval_statement_list): Ignore DEBUG_BEGIN_STMTs
in STATEMENT_LIST. Remove unneeded assert.
* g++.dg/cpp0x/pr83734.C: New test.
--- gcc/cp/constexpr.c.jj 2018-01-04 00:43:16.108702767 +0100
+++ gcc/cp/constexpr.c 2018-01-08 13:38:22.531365873 +0100
@@ -3851,6 +3851,8 @@ cxx_eval_statement_list (const constexpr
for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
{
tree stmt = tsi_stmt (i);
+ if (TREE_CODE (stmt) == DEBUG_BEGIN_STMT)
+ continue;
r = cxx_eval_constant_expression (ctx, stmt, false,
non_constant_p, overflow_p,
jump_target);
@@ -3859,14 +3861,6 @@ cxx_eval_statement_list (const constexpr
if (returns (jump_target) || breaks (jump_target))
break;
}
- /* Make sure we don't use the "result" of a debug-only marker. That
- would be wrong. We should be using the result of the previous
- statement, or NULL if there isn't one. In practice, this should
- never happen: the statement after the marker should override the
- result of the marker, so its value shouldn't survive in R. Now,
- should that ever change, we'll need some fixing here to stop
- markers from modifying the generated executable code. */
- gcc_checking_assert (!r || TREE_CODE (r) != DEBUG_BEGIN_STMT);
return r;
}
--- gcc/testsuite/g++.dg/cpp0x/pr83734.C.jj 2018-01-08 13:40:00.843390108
+0100
+++ gcc/testsuite/g++.dg/cpp0x/pr83734.C 2018-01-08 13:39:19.278379863
+0100
@@ -0,0 +1,6 @@
+// PR c++/83734
+// { dg-do compile { target c++11 } }
+// { dg-options "-g -O2" }
+
+struct A { constexpr A () { typedef int T; } };
+A a;
Jakub
