Add test for issue 6607

tests/source/issue-6607/fn-type.rs

diff --git a/tests/source/issue-6607/fn-type.rs b/tests/source/issue-6607/fn-type.rs
new file mode 100644
index 0000000..e85d04d
--- /dev/null
+++ b/tests/source/issue-6607/fn-type.rs
@@ -0,0 +1,3 @@
+struct Foo {
+    v: fn(#[cfg(false)] i32),
+}
\ No newline at end of file

tests/target/issue-6607/fn-type.rs

diff --git a/tests/target/issue-6607/fn-type.rs b/tests/target/issue-6607/fn-type.rs
new file mode 100644
index 0000000..7f89d12
--- /dev/null
+++ b/tests/target/issue-6607/fn-type.rs
@@ -0,0 +1,3 @@
+struct Foo {
+    v: fn(#[cfg(false)] i32),
+}