Fix compilation with #[deny(warnings)] with the ! type

rust-lang/rust#49039 (comment)

Author: TeXitoi

.travis.yml

@@ -7,9 +7,7 @@ rust:
 matrix:
   include:
     - rust: nightly
-      env: FEATURES="--features testing_only_proc_macro2_nightly"
-  allow_failures:
-    - rust: nightly
+      env: FEATURES="--features nightly"
 
 script:
   - cargo test $FEATURES

CHANGELOG.md

@@ -1,4 +1,6 @@
-# v0.2.5 (2018-XX-XX)
+# v0.2.6 (2018-XX-XX)
+
+* Fix compilation with `#[deny(warnings)]` with the `!` type (https://github.com/rust-lang/rust/pull/49039#issuecomment-376420816) by [@TeXitoi](https://github.com/TeXitoi)
 
 * Improve first example in the documentation ([#82](https://github.com/TeXitoi/structopt/issues/82)) by [@TeXitoi](https://github.com/TeXitoi)
 

Cargo.toml

@@ -12,7 +12,7 @@ readme = "README.md"
 
 [features]
 default = ["clap/default"]
-testing_only_proc_macro2_nightly = ["structopt-derive/testing_only_proc_macro2_nightly"]
+nightly = ["structopt-derive/nightly"]
 
 [badges]
 travis-ci = { repository = "TeXitoi/structopt" }

structopt-derive/Cargo.toml

@@ -18,7 +18,7 @@ quote = "0.4"
 proc-macro2 = "0.2"
 
 [features]
-testing_only_proc_macro2_nightly = ["proc-macro2/nightly"]
+nightly = ["proc-macro2/nightly"]
 
 [lib]
 proc-macro = true

structopt-derive/src/lib.rs

@@ -381,7 +381,7 @@ fn impl_structopt_for_struct(
             #from_clap
         }
 
-        #[allow(dead_code)]
+        #[allow(dead_code, unreachable_code)]
         #[doc(hidden)]
         impl #name {
             #augment_clap
@@ -406,7 +406,7 @@ fn impl_structopt_for_enum(
             #from_clap
         }
 
-        #[allow(unused_variables, dead_code)]
+        #[allow(unused_variables, dead_code, unreachable_code)]
         #[doc(hidden)]
         impl #name {
             #augment_clap

tests/deny-warnings.rs

@@ -0,0 +1,46 @@
+// Copyright 2018 Guillaume Pinot (@TeXitoi) <[email protected]>
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![deny(warnings)]
+#![cfg(feature = "nightly")]// TODO: remove that when never is stable
+
+#[macro_use]
+extern crate structopt;
+
+use structopt::StructOpt;
+
+fn try_str(s: &str) -> Result<String, !> {
+    Ok(s.into())
+}
+
+#[test]
+fn warning_never_struct() {
+    #[derive(Debug, PartialEq, StructOpt)]
+    struct Opt {
+        #[structopt(parse(try_from_str = "try_str"))]
+        s: String,
+    }
+    assert_eq!(Opt { s: "foo".to_string() },
+               Opt::from_iter(&["test", "foo"]));
+
+}
+
+#[test]
+fn warning_never_enum() {
+    #[derive(Debug, PartialEq, StructOpt)]
+    enum Opt {
+        Foo {
+            #[structopt(parse(try_from_str = "try_str"))]
+            s: String,
+        }
+    }
+    assert_eq!(Opt::Foo { s: "foo".to_string() },
+               Opt::from_iter(&["test", "Foo", "foo"]));
+
+}
+