cli: update to clap 4 (#108)

Specify next_display_order = None to keep the option list sorted in
--help.

Pretend to continue supporting clap 3 in Cargo.toml so cargo < 1.60
won't fail when building with the CLI disabled.  Delete Cargo.lock in
MSRV CI jobs for the same reason.

Author: bgilbert

.github/workflows/rust.yml

@@ -22,14 +22,16 @@ jobs:
         rust:
           - stable
           - 1.46.0 # lib MSRV
-          - 1.57.0 # cli MSRV
+          - 1.60.0 # cli MSRV
         include:
           - os: ubuntu-latest
             rust: stable
             lint: 1
           - rust: stable
             rust-args: --all-features
-          - rust: 1.57.0
+          - rust: 1.46.0
+            no-lock: 1
+          - rust: 1.60.0
             rust-args: --all-features
     runs-on: ${{ matrix.os }}
     steps:
@@ -44,6 +46,15 @@ jobs:
 
       - uses: Swatinem/rust-cache@v1
 
+      # If we're testing with Rust < 1.60, cargo won't be able to find
+      # the clap version specified in Cargo.lock, so remove the lockfile.
+      # This is safe because applications that only use us as a library will
+      # also ignore our Cargo.lock.
+      # https://users.rust-lang.org/t/optional-dependencies-and-msrv/82151
+      - name: Prune Cargo.lock
+        if: matrix.no-lock
+        run: rm Cargo.lock
+
       - name: cargo test
         uses: actions-rs/cargo@v1
         with:

Cargo.lock

@@ -33,7 +33,11 @@ pad = { version = "0.1", optional = true }
 unicode-width = { version = "0.1.8", optional = true }
 linefeed = { version = "0.6.0", optional = true }
 rand = { version = "0.8", optional = true }
-clap = { version = "3.1", optional = true, features = ["derive"] }
+# We don't actually support clap 3.  But cargo < 1.60 ignores clap versions
+# >= 4, and our MSRV is lower than that when the CLI is disabled.  Ensure
+# older cargo can find _some_ clap version so it won't fail.
+# https://users.rust-lang.org/t/optional-dependencies-and-msrv/82151
+clap = { version = ">= 3, < 5", optional = true, features = ["derive", "wrap_help"] }
 count-zeroes = { version = "0.2.0", optional = true }
 
 [features]

Cargo.toml

@@ -1,7 +1,7 @@
-use clap::{ArgEnum, Parser};
+use clap::{Parser, ValueEnum};
 use std::path::PathBuf;
 
-#[derive(ArgEnum, Clone, Debug)]
+#[derive(Clone, Debug, ValueEnum)]
 pub enum Column {
     Device,
     Start,
@@ -15,36 +15,36 @@ pub enum Column {
 }
 
 #[derive(Parser, Debug)]
-#[clap(version)]
+#[command(next_display_order = None, version)]
 pub struct Opt {
     /// display partitions and exit
-    #[clap(short = 'l', long = "list")]
+    #[arg(short = 'l', long = "list")]
     pub print: bool,
 
     /// output columns
-    #[clap(
+    #[arg(
         short = 'o',
         long = "output",
-        arg_enum,
+        value_enum,
         default_value = "device,start,end,sectors,size,type,guid,attributes,name",
-        use_value_delimiter = true
+        value_delimiter = ','
     )]
     pub columns: Vec<Column>,
 
     /// device to open
-    #[clap(name = "DEVICE", parse(from_os_str))]
+    #[arg(value_name = "DEVICE")]
     pub device: PathBuf,
 
     /// initialize a new GPT on the disk
-    #[clap(short = 'i', long = "init")]
+    #[arg(short = 'i', long = "init")]
     pub init: bool,
 
     /// sector size
-    #[clap(short = 'b', long = "sector-size")]
+    #[arg(short = 'b', long = "sector-size")]
     pub sector_size: Option<u64>,
 
     /// partition alignment
-    #[clap(short = 'a', long = "align")]
+    #[arg(short = 'a', long = "align")]
     pub align: Option<u64>,
 }