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C++ PATCH for c++/69842 (wrong error with generic lambda)
- From: Jason Merrill <jason at redhat dot com>
- To: gcc-patches List <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 17 Feb 2016 15:44:43 -0500
- Subject: C++ PATCH for c++/69842 (wrong error with generic lambda)
- Authentication-results: sourceware.org; auth=none
The problem here was that the call from the stub returned by the
conversion function to the op() was changing an xvalue to an lvalue,
leading to a parameter of the wrong type in the op().
Tested x86_64-pc-linux-gnu, applying to trunk.
commit 54448906d76dd9df2523e6c3950ed368cb63b4de
Author: Jason Merrill <jason@redhat.com>
Date: Wed Feb 17 15:20:02 2016 -0500
PR c++/69842
* method.c (forward_parm): Split out from...
(add_one_base_init): ...here.
* lambda.c (maybe_add_lambda_conv_op): Use it.
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 3b91089..7800ae8 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -6013,6 +6013,7 @@ extern tree make_thunk (tree, bool, tree, tree);
extern void finish_thunk (tree);
extern void use_thunk (tree, bool);
extern bool trivial_fn_p (tree);
+extern tree forward_parm (tree);
extern bool is_trivially_xible (enum tree_code, tree, tree);
extern tree get_defaulted_eh_spec (tree);
extern tree unevaluated_noexcept_spec (void);
diff --git a/gcc/cp/lambda.c b/gcc/cp/lambda.c
index 93b192c..296c6f7 100644
--- a/gcc/cp/lambda.c
+++ b/gcc/cp/lambda.c
@@ -962,7 +962,9 @@ maybe_add_lambda_conv_op (tree type)
}
else
{
- tree a = convert_from_reference (tgt);
+ ++processing_template_decl;
+ tree a = forward_parm (tgt);
+ --processing_template_decl;
CALL_EXPR_ARG (call, ix) = a;
if (decltype_call)
CALL_EXPR_ARG (decltype_call, ix) = copy_node (a);
diff --git a/gcc/cp/method.c b/gcc/cp/method.c
index e358ebd..f455b32 100644
--- a/gcc/cp/method.c
+++ b/gcc/cp/method.c
@@ -474,6 +474,19 @@ trivial_fn_p (tree fn)
return type_has_trivial_fn (DECL_CONTEXT (fn), special_function_p (fn));
}
+/* PARM is a PARM_DECL for a function which we want to forward to another
+ function without changing its value category, a la std::forward. */
+
+tree
+forward_parm (tree parm)
+{
+ tree exp = convert_from_reference (parm);
+ if (TREE_CODE (TREE_TYPE (parm)) != REFERENCE_TYPE
+ || TYPE_REF_IS_RVALUE (TREE_TYPE (parm)))
+ exp = move (exp);
+ return exp;
+}
+
/* Subroutine of do_build_copy_constructor: Add a mem-initializer for BINFO
given the parameter or parameters PARM, possibly inherited constructor
base INH, or move flag MOVE_P. */
@@ -494,10 +507,7 @@ add_one_base_init (tree binfo, tree parm, bool move_p, tree inh,
init = NULL_TREE;
for (; parm; parm = DECL_CHAIN (parm))
{
- tree exp = convert_from_reference (parm);
- if (TREE_CODE (TREE_TYPE (parm)) != REFERENCE_TYPE
- || TYPE_REF_IS_RVALUE (TREE_TYPE (parm)))
- exp = move (exp);
+ tree exp = forward_parm (parm);
*p = build_tree_list (NULL_TREE, exp);
p = &TREE_CHAIN (*p);
}
diff --git a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-conv1.C b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-conv1.C
new file mode 100644
index 0000000..6569af4
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-conv1.C
@@ -0,0 +1,14 @@
+// PR c++/69842
+// { dg-do compile { target c++14 } }
+
+template <class T, class U> struct same;
+template <class T> struct same<T,T> {};
+
+int main()
+{
+ auto g = [](auto && _var) {
+ same<int&&,decltype(_var)>();
+ };
+
+ g(0);
+}