While partially instantiating a generic lambda, we can encounter pack
expansions or constexpr if where we can't actually do the substitution
immediately, and instead remember a partial instantiation context
in *_EXTRA_ARGS. This includes any local_specializations used in the
pattern or condition. In this testcase our tree walk wasn't finding the use
of i because we weren't walking into the type of a CONSTRUCTOR. Fixed by
moving the code for doing that from find_parameter_packs_r into
cp_walk_subtrees.
Tested x86_64-pc-linux-gnu, applying to trunk.
2020-02-11 Jason Merrill <ja...@redhat.com>
PR c++/92583
PR c++/92654
* tree.c (cp_walk_subtrees): Walk CONSTRUCTOR types here.
* pt.c (find_parameter_packs_r): Not here.
---
gcc/cp/pt.c | 3 ---
gcc/cp/tree.c | 5 ++++
gcc/testsuite/g++.dg/cpp0x/nondeduced7.C | 2 +-
.../g++.dg/cpp1z/constexpr-if-lambda3.C | 24 +++++++++++++++++++
4 files changed, 30 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-if-lambda3.C
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index c2d3a98b1c5..6e7f4555da8 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -3924,9 +3924,6 @@ find_parameter_packs_r (tree *tp, int *walk_subtrees,
void* data)
case TEMPLATE_DECL:
if (!DECL_TEMPLATE_TEMPLATE_PARM_P (t))
return NULL_TREE;
- gcc_fallthrough();
-
- case CONSTRUCTOR:
cp_walk_tree (&TREE_TYPE (t),
&find_parameter_packs_r, ppd, ppd->visited);
return NULL_TREE;
diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
index eb540f851ee..736ef6fe667 100644
--- a/gcc/cp/tree.c
+++ b/gcc/cp/tree.c
@@ -5024,6 +5024,11 @@ cp_walk_subtrees (tree *tp, int *walk_subtrees_p,
walk_tree_fn func,
*walk_subtrees_p = 0;
break;
+ case CONSTRUCTOR:
+ if (COMPOUND_LITERAL_P (*tp))
+ WALK_SUBTREE (TREE_TYPE (*tp));
+ break;
+
case TRAIT_EXPR:
WALK_SUBTREE (TRAIT_EXPR_TYPE1 (*tp));
WALK_SUBTREE (TRAIT_EXPR_TYPE2 (*tp));
diff --git a/gcc/testsuite/g++.dg/cpp0x/nondeduced7.C
b/gcc/testsuite/g++.dg/cpp0x/nondeduced7.C
index a8aa073c57e..eb5d5faf493 100644
--- a/gcc/testsuite/g++.dg/cpp0x/nondeduced7.C
+++ b/gcc/testsuite/g++.dg/cpp0x/nondeduced7.C
@@ -2,5 +2,5 @@
// { dg-do compile { target c++11 } }
template<typename, int> struct A;
-template<typename T> struct A<T, T{}> {}; // { dg-error "partial
specialization" }
+template<typename T> struct A<T, T{}> {}; // { dg-error "partial
specialization|involves template parameter" }
A<int, 0> a;
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-if-lambda3.C
b/gcc/testsuite/g++.dg/cpp1z/constexpr-if-lambda3.C
new file mode 100644
index 00000000000..34615f71ee2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-if-lambda3.C
@@ -0,0 +1,24 @@
+// PR c++/92583
+// { dg-do compile { target c++17 } }
+
+template <int> struct a {
+ constexpr operator int() { return 42; }
+};
+template <typename> using b = int;
+template <typename d, d> struct e {};
+template <typename d, d g> using h = e<d, __integer_pack(g)...>;
+template <typename j, typename k, k... index> void apply(j f, e<k, index...>) {
+ (f(a<index>{}), ...);
+}
+template <auto l, typename j> void m(j f) {
+ using k = b<decltype(l)>;
+ using n = h<k, l>;
+ apply(f, n{});
+}
+template <int, int c> void o() {
+ auto p = [](auto i) {
+ if constexpr (a<i>{}) ;
+ };
+ m<c>(p);
+}
+auto q() { o<0, 1>; }
base-commit: 1cd9bef89ef25b3fd506cedbc82e8bc00ff56fa8
--
2.18.1
