c++: Fix decltype of empty pack expansion of parm.
In unevaluated context, we only substitute a single PARM_DECL, not the
entire chain, but the handling of an empty pack expansion was missing that
check.
gcc/cp/ChangeLog
2020-02-26 Jason Merrill <jason@redhat.com>
PR c++/93140
* pt.c (tsubst_decl) [PARM_DECL]: Check cp_unevaluated_operand in
handling of TREE_CHAIN for empty pack.
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index ca4bc4c..8c4d662 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,11 @@
2020-02-26 Jason Merrill <jason@redhat.com>
+ PR c++/93140
+ * pt.c (tsubst_decl) [PARM_DECL]: Check cp_unevaluated_operand in
+ handling of TREE_CHAIN for empty pack.
+
+2020-02-26 Jason Merrill <jason@redhat.com>
+
PR c++/92852
* constexpr.c (maybe_constant_value): Don't unshare if the cached
value is the same as the argument.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index c7245ef..c7ca7e4 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -13495,7 +13495,7 @@
/* Zero-length parameter packs are boring. Just substitute
into the chain. */
- if (len == 0)
+ if (len == 0 && !cp_unevaluated_operand)
RETURN (tsubst (TREE_CHAIN (t), args, complain,
TREE_CHAIN (t)));
}
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic-parm1.C b/gcc/testsuite/g++.dg/cpp0x/variadic-parm1.C
new file mode 100644
index 0000000..4300c78
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic-parm1.C
@@ -0,0 +1,17 @@
+// PR c++/93140
+// { dg-do compile { target c++11 } }
+
+int
+bar ()
+{
+ return 42;
+}
+
+template <typename... R>
+void foo (R... r, decltype (bar (r...)) x = 0) {}
+
+int
+main ()
+{
+ foo (3);
+}
