re PR c++/86767 (continue statements in constexpr functions causes unbounded looping)

	PR c++/86767
	* constexpr.c (cxx_eval_statement_list): Handle continue.

	* g++.dg/cpp1y/constexpr-86767.C: New test.

From-SVN: r263340

4 files changed, 139 insertions, 0 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 90af73d..7cf87f8 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2018-08-06  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/86767
+	* constexpr.c (cxx_eval_statement_list): Handle continue.
+
 2018-08-03  David Malcolm  <dmalcolm@redhat.com>
 	    Jonathan Wakely  <jwakely@redhat.com>
 
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index 365296d..79039ff 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -3950,6 +3950,16 @@ cxx_eval_statement_list (const constexpr_ctx *ctx, tree t,
   for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
     {
       tree stmt = tsi_stmt (i);
+      /* We've found a continue, so skip everything until we reach
+	 the label its jumping to.  */
+      if (continues (jump_target))
+	{
+	  if (label_matches (ctx, jump_target, stmt))
+	    /* Found it.  */
+	    *jump_target = NULL_TREE;
+	  else
+	    continue;
+	}
       if (TREE_CODE (stmt) == DEBUG_BEGIN_STMT)
 	continue;
       r = cxx_eval_constant_expression (ctx, stmt, false,
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 71e3ad7..eec7461 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-08-06  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/86767
+	* g++.dg/cpp1y/constexpr-86767.C: New test.
+
 2018-08-06  Uros Bizjak  <ubizjak@gmail.com>
 
 	* g++.dg/torture/pr86763.C (dg-additional-options): Add -lrt
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-86767.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-86767.C
new file mode 100644
index 0000000..2ad71d5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-86767.C
@@ -0,0 +1,119 @@
+// PR c++/86767
+// { dg-do compile { target c++14 } }
+
+constexpr int
+fn0 () noexcept
+{
+  int r = 0;
+  for (int i = 0; i < 10; ++i)
+    {
+      continue;
+      r++;
+      for (int j = 0; j < 10; ++j )
+	{
+	}
+    }
+  return r;
+}
+static_assert (fn0 () == 0, "");
+
+constexpr int
+fn1 () noexcept
+{
+  int r = 0;
+  for (int i = 0; i < 10; ++i)
+    for (int j = 0; j < 10; ++j)
+      {
+	continue;
+	r++;
+      }
+  return r;
+}
+static_assert (fn1 () == 0, "");
+
+constexpr int
+fn2 () noexcept
+{
+  int r = 0;
+  for (int i = 0; i < 10; ++i)
+    {
+      continue;
+      r++;
+    }
+  return r;
+}
+static_assert (fn2 () == 0, "");
+
+constexpr int
+fn3 () noexcept
+{
+  int r = 0;
+  for (int i = 0; i < 10; ++i)
+    {
+      continue;
+      r++;
+      while (1)
+	{
+	}
+    }
+  return r;
+}
+static_assert (fn3 () == 0, "");
+
+constexpr int
+fn4 () noexcept
+{
+  for (int i = 0; i < 10; ++i)
+    {
+      switch (i)
+	{
+	case 5:
+	  return i;
+	default:
+	  continue;
+	}
+      while (1)
+	{
+	}
+    }
+  return 0;
+}
+static_assert (fn4 () == 5, "");
+
+constexpr int
+fn5 () noexcept
+{
+  for (int i = 0; i < 10; ++i)
+    {
+      switch (i)
+	{
+	case 0:
+	case 1:
+	case 2:
+	case 3:
+	case 4:
+	  continue;
+	default:
+	  return i;
+	}
+      while (1)
+	{
+	}
+    }
+  return 0;
+}
+static_assert (fn5 () == 5, "");
+
+constexpr int
+fn6 () noexcept
+{
+  int r = 0;
+  for (int i = 0; i < 10; ++i)
+    {
+      continue;
+      for (int j = 0; j < 10; ++j )
+	r++;
+    }
+  return r;
+}
+static_assert (fn6 () == 0, "");