When we partially instantiate the constexpr if, we walk through its body to
see what it uses from the enclosing local_specializations. That walk was
overlooking the use of 'count' in the captures of the innermost lambda,
because we weren't walking into the capture list.
Tested x86_64-pc-linux-gnu, applying to trunk.
* tree.c (cp_walk_subtrees): Handle LAMBDA_EXPR.
---
gcc/cp/tree.c | 8 ++++++
gcc/testsuite/g++.dg/cpp1z/constexpr-if25.C | 27 +++++++++++++++++++++
gcc/cp/ChangeLog | 5 ++++
3 files changed, 40 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-if25.C
diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
index 50002161500..be33d4186f9 100644
--- a/gcc/cp/tree.c
+++ b/gcc/cp/tree.c
@@ -4933,6 +4933,14 @@ cp_walk_subtrees (tree *tp, int *walk_subtrees_p,
walk_tree_fn func,
}
break;
+ case LAMBDA_EXPR:
+ /* Don't walk into the body of the lambda, but the capture initializers
+ are part of the enclosing context. */
+ for (tree cap = LAMBDA_EXPR_CAPTURE_LIST (*tp); cap;
+ cap = TREE_CHAIN (cap))
+ WALK_SUBTREE (TREE_VALUE (cap));
+ break;
+
default:
return NULL_TREE;
}
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-if25.C
b/gcc/testsuite/g++.dg/cpp1z/constexpr-if25.C
new file mode 100644
index 00000000000..144139ea196
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-if25.C
@@ -0,0 +1,27 @@
+// PR c++/86740
+// { dg-do compile { target c++17 } }
+
+struct Constant
+{
+ static constexpr int value = 0;
+};
+template<typename F>
+void invokeWithConstant(F &&f)
+{
+ f(Constant{});
+}
+int foo()
+{
+ int count = 0;
+ invokeWithConstant
+ ([&] (auto id1)
+ {
+ invokeWithConstant
+ ([&] (auto id2)
+ {
+ if constexpr (id1.value == 0 && id2.value == 0)
+ [&] { count = 1; } ();
+ });
+ });
+ return count;
+}
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 05e8566e493..01a57601f4c 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2019-01-17 Jason Merrill <ja...@redhat.com>
+
+ PR c++/86740, ICE with constexpr if and nested generic lambdas.
+ * tree.c (cp_walk_subtrees): Handle LAMBDA_EXPR.
+
2019-01-17 Paolo Carlini <paolo.carl...@oracle.com>
* decl.c (grokdeclarator): Use typespec_loc in error messages
base-commit: 7e351bf905bf4b0ad84bf9dae79032f8c41f0e03
--
2.20.1
