Split short summary from full help text

b3sum/Cargo.toml

@@ -16,7 +16,7 @@ pure = ["blake3/pure"]
 [dependencies]
 anyhow = "1.0.25"
 blake3 = { version = "1", path = "..", features = ["rayon"] }
-clap = { version = "4.0.8", features = ["derive"] }
+clap = { version = "4.0.8", features = ["derive", "wrap_help"] }
 hex = "0.4.0"
 memmap2 = "0.5.3"
 rayon = "1.2.1"

b3sum/README.md

@@ -8,31 +8,31 @@ Coreutils tools like `b2sum` or `md5sum`.
 Usage: b3sum [OPTIONS] [FILE]...
 
 Arguments:
-  [FILE]...  Files to hash, or checkfiles to check. When no file is given,
-             or when - is given, read standard input.
+  [FILE]...  Files to hash, or checkfiles to check
 
 Options:
-  -l, --length <LEN>          The number of output bytes, prior to hex
-                              encoding [default: 32]
-      --num-threads <NUM>     The maximum number of threads to use. By
-                              default, this is the number of logical cores.
-                              If this flag is omitted, or if its value is 0,
-                              RAYON_NUM_THREADS is also respected.
-      --keyed                 Uses the keyed mode. The secret key is read from standard
-                              input, and it must be exactly 32 raw bytes.
-      --derive-key <CONTEXT>  Uses the key derivation mode, with the given
-                              context string. Cannot be used with --keyed.
-      --no-mmap               Disables memory mapping. Currently this also disables
-                              multithreading.
-      --no-names              Omits filenames in the output
-      --raw                   Writes raw output bytes to stdout, rather than hex.
-                              --no-names is implied. In this case, only a single
-                              input is allowed.
-  -c, --check                 Reads BLAKE3 sums from the [FILE]s and checks them
-      --quiet                 Skips printing OK for each successfully verified file.
-                              Must be used with --check.
-  -h, --help                  Print help information
-  -V, --version               Print version information
+  -l, --length <LEN>
+          The number of output bytes, prior to hex encoding [default: 32]
+      --num-threads <NUM>
+          The maximum number of threads to use
+      --keyed
+          Uses the keyed mode
+      --derive-key <CONTEXT>
+          Uses the key derivation mode, with the given context string
+      --no-mmap
+          Disables memory mapping
+      --no-names
+          Omits filenames in the output
+      --raw
+          Writes raw output bytes to stdout, rather than hex
+  -c, --check
+          Reads BLAKE3 sums from the [FILE]s and checks them
+      --quiet
+          Skips printing OK for each successfully verified file
+  -h, --help
+          Print help information (use `--help` for more detail)
+  -V, --version
+          Print version information
 ```
 
 See also [this document about how the `--check` flag

b3sum/src/main.rs

@@ -20,62 +20,59 @@ const RAW_ARG: &str = "raw";
 const CHECK_ARG: &str = "check";
 
 #[derive(Parser)]
-#[command(version)]
+#[command(version, max_term_width(80))]
 struct Inner {
-    /// Files to hash, or checkfiles to check. When no file is given,
-    /// or when - is given, read standard input.
-    #[arg(verbatim_doc_comment)]
+    /// Files to hash, or checkfiles to check.
+    ///
+    /// When no file is given, or when - is given, read standard input.
     file: Vec<PathBuf>,
 
-    /// The number of output bytes, prior to hex
-    /// encoding
+    /// The number of output bytes, prior to hex encoding.
     #[arg(
-        verbatim_doc_comment,
         short,
         long,
         default_value_t = blake3::OUT_LEN as u64,
         value_name("LEN")
     )]
     length: u64,
 
-    /// The maximum number of threads to use. By
-    /// default, this is the number of logical cores.
-    /// If this flag is omitted, or if its value is 0,
-    /// RAYON_NUM_THREADS is also respected.
-    #[arg(verbatim_doc_comment, long, value_name("NUM"))]
+    /// The maximum number of threads to use.
+    ///
+    /// By default, this is the number of logical cores. If this flag is
+    /// omitted, or if its value is 0, RAYON_NUM_THREADS is also respected.
+    #[arg(long, value_name("NUM"))]
     num_threads: Option<usize>,
 
-    /// Uses the keyed mode. The secret key is read from standard
-    /// input, and it must be exactly 32 raw bytes.
-    #[arg(verbatim_doc_comment, long, requires("file"))]
+    /// Uses the keyed mode.
+    ///
+    /// The secret key is read from standard input, and it must be exactly 32
+    /// raw bytes.
+    #[arg(long, requires("file"))]
     keyed: bool,
 
-    /// Uses the key derivation mode, with the given
-    /// context string. Cannot be used with --keyed.
-    #[arg(
-        verbatim_doc_comment,
-        long,
-        value_name("CONTEXT"),
-        conflicts_with(KEYED_ARG)
-    )]
+    /// Uses the key derivation mode, with the given context string.
+    ///
+    /// Cannot be used with --keyed.
+    #[arg(long, value_name("CONTEXT"), conflicts_with(KEYED_ARG))]
     derive_key: Option<String>,
 
-    /// Disables memory mapping. Currently this also disables
-    /// multithreading.
-    #[arg(verbatim_doc_comment, long)]
+    /// Disables memory mapping.
+    ///
+    /// Currently this also disables multithreading.
+    #[arg(long)]
     no_mmap: bool,
 
-    /// Omits filenames in the output
+    /// Omits filenames in the output.
     #[arg(long)]
     no_names: bool,
 
     /// Writes raw output bytes to stdout, rather than hex.
-    /// --no-names is implied. In this case, only a single
-    /// input is allowed.
-    #[arg(verbatim_doc_comment, long)]
+    ///
+    /// --no-names is implied. In this case, only a single input is allowed.
+    #[arg(long)]
     raw: bool,
 
-    /// Reads BLAKE3 sums from the [FILE]s and checks them
+    /// Reads BLAKE3 sums from the [FILE]s and checks them.
     #[arg(
         short,
         long,
@@ -88,8 +85,9 @@ struct Inner {
     check: bool,
 
     /// Skips printing OK for each successfully verified file.
+    ///
     /// Must be used with --check.
-    #[arg(verbatim_doc_comment, long, requires(CHECK_ARG))]
+    #[arg(long, requires(CHECK_ARG))]
     quiet: bool,
 }