examples: replace structopt with clap

See TeXitoi/structopt#525.

Currently codespan-reporting is the second most downloaded dependent of
structopt: https://crates.io/crates/structopt/reverse_dependencies.

codespan-reporting/Cargo.toml

@@ -22,7 +22,9 @@ insta = "1.6.3"
 lazy_static = "1.4"
 peg = "0.7"
 rustyline = "6"
-structopt = "0.3"
+# Latest is 4.4.13 but specifies MSRV in Cargo.toml which means we can't depend
+# on it (even though we won't compile it in MSRV CI).
+clap = { version = "3.2.25", features = ["derive"] }
 unindent = "0.1"
 
 [features]

codespan-reporting/examples/readme_preview.rs

@@ -7,27 +7,25 @@
 //! cargo run --example readme_preview svg > codespan-reporting/assets/readme_preview.svg
 //! ```
 
+use clap::Parser;
 use codespan_reporting::diagnostic::{Diagnostic, Label};
 use codespan_reporting::files::SimpleFile;
 use codespan_reporting::term::termcolor::{Color, ColorSpec, StandardStream, WriteColor};
 use codespan_reporting::term::{self, ColorArg};
 use std::io::{self, Write};
-use structopt::StructOpt;
 
-#[derive(Debug, StructOpt)]
-#[structopt(name = "emit")]
+#[derive(Debug, Parser)]
+#[clap(name = "emit")]
 pub enum Opts {
     /// Render SVG output
     Svg,
     /// Render Stderr output
     Stderr {
         /// Configure coloring of output
-        #[structopt(
+        #[clap(
             long = "color",
-            parse(try_from_str),
             default_value = "auto",
-            possible_values = ColorArg::VARIANTS,
-            case_insensitive = true
+            value_parser = clap::builder::PossibleValuesParser::new(ColorArg::VARIANTS),
         )]
         color: ColorArg,
     },
@@ -77,7 +75,7 @@ fn main() -> anyhow::Result<()> {
         )])];
 
     // let mut files = SimpleFiles::new();
-    match Opts::from_args() {
+    match Opts::parse() {
         Opts::Svg => {
             let mut buffer = Vec::new();
             let mut writer = HtmlEscapeWriter::new(SvgWriter::new(&mut buffer));

codespan-reporting/examples/reusable_diagnostic.rs

@@ -1,18 +1,16 @@
+use clap::Parser;
 use codespan_reporting::diagnostic::{Diagnostic, Label};
 use codespan_reporting::files::SimpleFile;
 use codespan_reporting::term::termcolor::StandardStream;
 use codespan_reporting::term::{self, ColorArg};
 use std::ops::Range;
-use structopt::StructOpt;
 
-#[derive(Debug, StructOpt)]
-#[structopt(name = "emit")]
+#[derive(Debug, Parser)]
+#[clap(name = "emit")]
 pub struct Opts {
-    #[structopt(long = "color",
-        parse(try_from_str),
+    #[clap(long = "color",
         default_value = "auto",
-        possible_values = ColorArg::VARIANTS,
-        case_insensitive = true
+        value_parser = clap::builder::PossibleValuesParser::new(ColorArg::VARIANTS),
     )]
     color: ColorArg,
 }
@@ -38,7 +36,7 @@ fn main() -> anyhow::Result<()> {
         Error::MutatingImmutable(Item::new(20..23, "foo"), Item::new(51..59, "foo += 1")),
     ];
 
-    let opts = Opts::from_args();
+    let opts = Opts::parse();
     let writer = StandardStream::stderr(opts.color.into());
     let config = codespan_reporting::term::Config::default();
     for diagnostic in errors.iter().map(Error::report) {

codespan-reporting/examples/term.rs

@@ -5,28 +5,26 @@
 //! cargo run --example term
 //! ```
 
+use clap::Parser;
 use codespan_reporting::diagnostic::{Diagnostic, Label};
 use codespan_reporting::files::SimpleFiles;
 use codespan_reporting::term::termcolor::StandardStream;
 use codespan_reporting::term::{self, ColorArg};
-use structopt::StructOpt;
 
-#[derive(Debug, StructOpt)]
-#[structopt(name = "emit")]
+#[derive(Debug, Parser)]
+#[clap(name = "emit")]
 pub struct Opts {
     /// Configure coloring of output
-    #[structopt(
+    #[clap(
         long = "color",
-        parse(try_from_str),
         default_value = "auto",
-        possible_values = ColorArg::VARIANTS,
-        case_insensitive = true
+        value_parser = clap::builder::PossibleValuesParser::new(ColorArg::VARIANTS),
     )]
     pub color: ColorArg,
 }
 
 fn main() -> anyhow::Result<()> {
-    let opts = Opts::from_args();
+    let opts = Opts::parse();
     let mut files = SimpleFiles::new();
 
     let file_id1 = files.add(

codespan-reporting/src/term.rs

@@ -16,32 +16,31 @@ pub use self::config::{Chars, Config, DisplayStyle, Styles};
 
 /// A command line argument that configures the coloring of the output.
 ///
-/// This can be used with command line argument parsers like [`clap`] or [`structopt`].
+/// This can be used with command line argument parsers like [`clap`] or [`Parser`].
 ///
 /// [`clap`]: https://crates.io/crates/clap
-/// [`structopt`]: https://crates.io/crates/structopt
+/// [`Parser`]: https://crates.io/crates/Parser
 ///
 /// # Example
 ///
 /// ```rust
 /// use codespan_reporting::term::termcolor::StandardStream;
 /// use codespan_reporting::term::ColorArg;
-/// use structopt::StructOpt;
+/// use clap::Parser;
 ///
-/// #[derive(Debug, StructOpt)]
-/// #[structopt(name = "groovey-app")]
+/// #[derive(Debug, Parser)]
+/// #[clap(name = "groovey-app")]
 /// pub struct Opts {
 ///     /// Configure coloring of output
-///     #[structopt(
+///     #[clap(
 ///         long = "color",
 ///         default_value = "auto",
-///         possible_values = ColorArg::VARIANTS,
-///         case_insensitive = true,
+///         value_parser = clap::builder::PossibleValuesParser::new(ColorArg::VARIANTS),
 ///     )]
 ///     pub color: ColorArg,
 /// }
 ///
-/// let opts = Opts::from_args();
+/// let opts = Opts::parse();
 /// let writer = StandardStream::stderr(opts.color.into());
 /// ```
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
@@ -50,11 +49,10 @@ pub struct ColorArg(pub ColorChoice);
 impl ColorArg {
     /// Allowed values the argument.
     ///
-    /// This is useful for generating documentation via [`clap`] or `structopt`'s
-    /// `possible_values` configuration.
+    /// This is useful for generating documentation via [`clap`]'s
+    /// `value_parser = clap::builder::PossibleValuesParser::new` configuration.
     ///
     /// [`clap`]: https://crates.io/crates/clap
-    /// [`structopt`]: https://crates.io/crates/structopt
     pub const VARIANTS: &'static [&'static str] = &["auto", "always", "ansi", "never"];
 }