re PR c++/69995 ([C++14] Invalid result when evaluating constexpr function)

	PR c++/69995

	* constexpr.c (cxx_eval_call_expression): Unshare arg.
	(cxx_eval_constant_expression) [DECL_EXPR]: Unshare init.
	[TARGET_EXPR]: Unshare init.

From-SVN: r233877

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 04e14268459818453b5732ba6f911ae2dfa49d22..3a24cc9392b8665b4e1e360bbdbe88bd58d6eb16 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,10 @@
+2016-03-01  Jason Merrill  <jason@redhat.com>
+
+       PR c++/69995
+       * constexpr.c (cxx_eval_call_expression): Unshare arg.
+       (cxx_eval_constant_expression) [DECL_EXPR]: Unshare init.
+       [TARGET_EXPR]: Unshare init.
+
 2016-03-01  Patrick Palka  <ppalka@gcc.gnu.org>
 
        PR c++/68948

diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index 5e359404c8d64462f64d0bc18fdb37b67c1dbf37..a21997ab97a3305b865e0499690dfca849ef784a 100644 (file)
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -1365,6 +1365,8 @@ cxx_eval_call_expression (const constexpr_ctx *ctx, tree t,
              tree oparm = TREE_PURPOSE (bound);
              tree arg = TREE_VALUE (bound);
              gcc_assert (DECL_NAME (remapped) == DECL_NAME (oparm));
+             /* Don't share a CONSTRUCTOR that might be changed.  */
+             arg = unshare_expr (arg);
              ctx->values->put (remapped, arg);
              bound = TREE_CHAIN (bound);
              remapped = DECL_CHAIN (remapped);
@@ -3366,6 +3368,8 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
            init = cxx_eval_constant_expression (ctx, init,
                                                 false,
                                                 non_constant_p, overflow_p);
+           /* Don't share a CONSTRUCTOR that might be changed.  */
+           init = unshare_expr (init);
            ctx->values->put (r, init);
          }
        else if (ctx == &new_ctx)
@@ -3410,6 +3414,7 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
       if (lval)
        {
          tree slot = TARGET_EXPR_SLOT (t);
+         r = unshare_expr (r);
          ctx->values->put (slot, r);
          return slot;
        }

diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-copy2.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-copy2.C
new file mode 100644 (file)
index 0000000..6707975
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-copy2.C
@@ -0,0 +1,24 @@
+// PR c++/69995
+// { dg-do compile { target c++14 } }
+
+struct A
+{
+  int i;
+};
+
+constexpr int f(A a)
+{
+  ++a.i;
+  return a.i;
+}
+
+constexpr bool g()
+{
+  A a = { 42 };
+  if (f(a) != 43) return false;
+  if (a.i != 42) return false;
+  return true;
+}
+
+#define SA(X) static_assert((X),#X)
+SA(g());

diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-copy3.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-copy3.C
new file mode 100644 (file)
index 0000000..cce4b54
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-copy3.C
@@ -0,0 +1,26 @@
+// PR c++/69995
+// { dg-do compile { target c++14 } }
+
+struct A
+{
+  int i;
+};
+
+constexpr int f(A a)
+{
+  ++a.i;
+  return a.i;
+}
+
+constexpr bool g()
+{
+  A a = { 42 };
+  A b = a;
+  ++b.i;
+  if (b.i != 43) return false;
+  if (a.i != 42) return false;
+  return true;
+}
+
+#define SA(X) static_assert((X),#X)
+SA(g());