c++: trivial lambda pruning [PR120716]

In this testcase there is nothing in the lambda except a static_assert which
mentions a variable from the enclosing scope but does not odr-use it, so we
want prune_lambda_captures to remove its capture.  Since the lambda is so
empty, there's nothing in the body except the DECL_EXPR of the capture
proxy, so pop_stmt_list moves that into the enclosing STATEMENT_LIST and
passes the 'body' STATEMENT_LIST to free_stmt_list.  As a result, passing
'body' to prune_lambda_captures is wrong; we should instead pass the
enclosing scope, i.e. cur_stmt_list.

	PR c++/120716

gcc/cp/ChangeLog:

	* lambda.cc (finish_lambda_function): Pass cur_stmt_list to
	prune_lambda_captures.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/lambda/lambda-constexpr3.C: New test.
	* g++.dg/cpp0x/lambda/lambda-constexpr3a.C: New test.

diff --git a/gcc/cp/lambda.cc b/gcc/cp/lambda.cc
index ae732c3f72a62d4436fae9e2a96fb6c911a7d8bc..182cffaf8d4f5158748104f41a73b699c6b334fe 100644 (file)
--- a/gcc/cp/lambda.cc
+++ b/gcc/cp/lambda.cc
@@ -1950,7 +1950,7 @@ finish_lambda_function (tree body)
 {
   finish_function_body (body);
 
-  prune_lambda_captures (body);
+  prune_lambda_captures (cur_stmt_list);
 
   /* Finish the function and generate code for it if necessary.  */
   tree fn = finish_function (/*inline_p=*/true);

diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-constexpr3.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-constexpr3.C
new file mode 100644 (file)
index 0000000..6525213
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-constexpr3.C
@@ -0,0 +1,13 @@
+// PR c++/120716
+// { dg-do compile { target c++11 } }
+
+struct A { int *r; };
+
+void
+foo ()
+{
+  static int i;
+  constexpr A a = { &i };
+  static_assert (a.r == &i, "");
+  [&] { static_assert (a.r != nullptr, ""); } ();
+}

diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-constexpr3a.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-constexpr3a.C
new file mode 100644 (file)
index 0000000..398e079
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-constexpr3a.C
@@ -0,0 +1,12 @@
+// PR c++/120716
+// { dg-do compile { target c++11 } }
+
+struct A { int *const &r; };
+
+void
+foo (int x)
+{
+  constexpr A a = { &x };      // { dg-error "constant" }
+  static_assert (a.r == &x, "");       // { dg-error "non-constant" }
+  [&] { static_assert (a.r != nullptr, ""); } (); // { dg-error "non-constant" }
+}