Add structopt dependency in version 0.3.7

This patch series replaces argparse with structopt in the argument
handling code. As a first step, we need structopt as a dependency.

Import subrepo structopt/:structopt at efbdda4753592e27bc430fb01f7b9650b2f3174d
Import subrepo bitflags/:bitflags at 30668016aca6bd3b02c766e8347e0b4080d4c296
Import subrepo clap/:clap at 784524f7eb193e35f81082cc69454c8c21b948f7
Import subrepo heck/:heck at 093d56fbf001e1506e56dbfa38631d99b1066df1
Import subrepo proc-macro-error/:proc-macro-error at 6c4cfe79a622c5de8ae68557993542be46eacae2
Import subrepo proc-macro2/:proc-macro2 at d5d48eddca4566e5438e8a2cbed4a74e049544de
Import subrepo quote/:quote at 727436c6c137b20f0f34dde5d8fda2679b9747ad
Import subrepo rustversion/:rustversion at 0c5663313516263059ce9059ef81fc7a1cf655ca
Import subrepo syn-mid/:syn-mid at 5d3d85414a9e6674e1857ec22a87b96e04a6851a
Import subrepo syn/:syn at e87c27e87f6f4ef8919d0372bdb056d53ef0d8f3
Import subrepo textwrap/:textwrap at abcd618beae3f74841032aa5b53c1086b0a57ca2
Import subrepo unicode-segmentation/:unicode-segmentation at 637c9874c4fe0c205ff27787faf150a40295c6c3
Import subrepo unicode-width/:unicode-width at 3033826f8bf05e82724140a981d5941e48fce393
Import subrepo unicode-xid/:unicode-xid at 4baae9fffb156ba229665b972a9cd5991787ceb7

2 files changed, 23 insertions, 0 deletions

diff --git a/syn/tests/features/error.rs b/syn/tests/features/error.rs
new file mode 100644
index 0000000..10ac889
--- /dev/null
+++ b/syn/tests/features/error.rs
@@ -0,0 +1 @@
+"Hello! You want: cargo test --release --all-features"
diff --git a/syn/tests/features/mod.rs b/syn/tests/features/mod.rs
new file mode 100644
index 0000000..83fbe13
--- /dev/null
+++ b/syn/tests/features/mod.rs
@@ -0,0 +1,22 @@
+#[allow(unused_macros)]
+macro_rules! hide_from_rustfmt {
+    ($mod:item) => {
+        $mod
+    };
+}
+
+#[cfg(not(all(
+    feature = "derive",
+    feature = "full",
+    feature = "parsing",
+    feature = "printing",
+    feature = "visit",
+    feature = "visit-mut",
+    feature = "fold",
+    feature = "clone-impls",
+    feature = "extra-traits",
+    feature = "proc-macro",
+)))]
+hide_from_rustfmt! {
+    mod error;
+}