Fix -Z minimal-versions

Cargo.toml

@@ -30,7 +30,7 @@ docmatic = "^0.1.2"
 
 [build-dependencies]
 regex = "1.0"
-version_check = "0.1"
+version_check = "0.1.3"
 
 [features]
 default = []
@@ -41,9 +41,6 @@ python2 = []
 # Use this feature when building python3 binding.
 python3 = []
 
-# Enable additional features that require nightly rust
-#nightly = []
-
 # Use this feature when building an extension module.
 # It tells the linker to keep the python symbols unresolved,
 # so that the module can also be used with statically linked python interpreters.

pyo3-derive-backend/Cargo.toml

@@ -13,7 +13,9 @@ license = "Apache-2.0"
 [dependencies]
 log="0.4"
 quote="0.5"
+# proc-macro2 is pinned to -Z minimal-versions pass (until the next syn upgrade)
+proc-macro2="0.3.8"
 
 [dependencies.syn]
-version="0.13"
+version="0.13.11"
 features=["full", "parsing", "printing", "extra-traits"]

src/objects/num3.rs

@@ -136,14 +136,12 @@ int_convert_bignum!(u128, 16, IS_LITTLE_ENDIAN, 0);
 
 #[cfg(test)]
 mod test {
-    use python::Python;
-    use conversion::ToPyObject;
-
     macro_rules! test_common (
         ($test_mod_name:ident, $t:ty) => (
             mod $test_mod_name {
-                use super::*;
                 use objects::exc;
+                use conversion::ToPyObject;
+                use python::Python;
 
                 #[test]
                 fn from_py_string_type_error() {