feat(derive): Start unstable-v4 feature flag

.github/workflows/ci.yml

@@ -112,6 +112,10 @@ jobs:
   ui:
     name: UI Tests
     runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        features: [default, next]
     steps:
     - name: Checkout repository
       uses: actions/checkout@v3
@@ -123,7 +127,7 @@ jobs:
         override: true
     - uses: Swatinem/rust-cache@v1
     - name: UI Tests
-      run: make test-ui
+      run: make test-ui-${{ matrix.features }}
   docs:
     name: Docs
     runs-on: ubuntu-latest

Cargo.toml

@@ -82,7 +82,8 @@ unicode = ["textwrap/unicode-width", "unicase"]  # Support for unicode character
 unstable-replace = []
 unstable-multicall = []
 unstable-grouped = []
-unstable-v4 = []
+# note: this will always enable clap_derive, change this to `clap_derive?/unstable-v4` when MSRV is bigger than 1.60
+unstable-v4 = ["clap_derive/unstable-v4"]
 
 [lib]
 bench = false

Makefile

@@ -33,5 +33,5 @@ test-%:
 clippy-%:
 	cargo clippy ${_FEATURES_${@:clippy-%=%}} ${ARGS} --all-targets -- -D warnings -A deprecated
 
-test-ui:
-	cargo +${MSRV} test --test derive_ui --features derive
+test-ui-%:
+	cargo +${MSRV} test --test derive_ui --features derive ${_FEATURES_${@:test-ui-%=%}}

clap_derive/Cargo.toml

@@ -44,6 +44,7 @@ proc-macro-error = "1"
 [features]
 default = []
 debug = []
+unstable-v4 = []
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]

tests/derive_ui.rs

@@ -11,4 +11,8 @@
 fn ui() {
     let t = trybuild::TestCases::new();
     t.compile_fail("tests/derive_ui/*.rs");
+    #[cfg(feature = "unstable-v4")]
+    t.compile_fail("tests/derive_ui/next/*.rs");
+    #[cfg(not(feature = "unstable-v4"))]
+    t.compile_fail("tests/derive_ui/stable/*.rs");
 }

tests/derive_ui/next/tuple_struct.stderr

@@ -0,0 +1,20 @@
+error: `#[derive(Parser)]` only supports non-tuple structs and enums
+  --> tests/derive_ui/next/tuple_struct.rs:11:10
+   |
+11 | #[derive(Parser, Debug)]
+   |          ^^^^^^
+   |
+   = note: this error originates in the derive macro `Parser` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0599]: no function or associated item named `parse` found for struct `Opt` in the current scope
+  --> tests/derive_ui/next/tuple_struct.rs:16:20
+   |
+13 | struct Opt(u32);
+   | ---------------- function or associated item `parse` not found for this
+...
+16 |     let opt = Opt::parse();
+   |                    ^^^^^ function or associated item not found in `Opt`
+   |
+   = help: items from traits can only be used if the trait is implemented and in scope
+   = note: the following trait defines an item `parse`, perhaps you need to implement it:
+           candidate #1: `StructOpt`

tests/derive_ui/stable/tuple_struct.rs

@@ -0,0 +1,18 @@
+// Copyright 2018 Guillaume Pinot (@TeXitoi) <texitoi@texitoi.eu>
+//
+// 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.
+
+use clap::Parser;
+
+#[derive(Parser, Debug)]
+#[clap(name = "basic")]
+struct Opt(u32);
+
+fn main() {
+    let opt = Opt::parse();
+    println!("{:?}", opt);
+}