fix: Don't suggest values for boolean options

The man generation would generate suggestions for all options of
values they should take, even if the argument did not take values.
This adds a simple check to make sure only options that take values
offer a suggestion

fixes: clap-rs#4443

clap_mangen/src/render.rs

@@ -99,9 +99,11 @@ pub(crate) fn options(roff: &mut Roff, cmd: &clap::Command) {
             (None, None) => vec![],
         };
 
-        if let Some(value) = &opt.get_value_names() {
-            header.push(roman("="));
-            header.push(italic(&value.join(" ")));
+        if opt.get_action().takes_values() {
+            if let Some(value) = &opt.get_value_names() {
+                header.push(roman("="));
+                header.push(italic(&value.join(" ")));
+            }
         }
 
         if let Some(defs) = option_default_values(opt) {

clap_mangen/tests/common.rs

@@ -312,3 +312,20 @@ pub fn possible_values_command(name: &'static str) -> clap::Command {
                 ]),
         )
 }
+
+
+/// Checks to make sure boolean valued "Flag options" do not generate
+/// suggestions for a parameter. i.e:
+///     --boolean_flag=BOOLEAN_FLAG
+///
+/// This is both confusing and suggest erroneous behavior as clap will fail if you
+/// pass a value to a boolean flag
+pub fn flag_without_value(name: &'static str) -> clap::Command {
+    clap::Command::new(name)
+        .arg(
+            clap::Arg::new("is_bool")
+                .long("is_bool")
+                .action(clap::ArgAction::SetTrue)
+        )
+}
+

clap_mangen/tests/roff.rs

@@ -70,6 +70,13 @@ fn possible_values() {
     common::assert_matches_path("tests/snapshots/possible_values.bash.roff", cmd);
 }
 
+#[test]
+fn flag_without_value() {
+    let name = "my-app";
+    let cmd = common::flag_without_value(name);
+    common::assert_matches_path("tests/snapshots/flag_without_value.bash.roff", cmd);
+}
+
 #[test]
 fn sub_subcommands_help() {
     let name = "my-app";

clap_mangen/tests/snapshots/flag_without_value.bash.roff

@@ -0,0 +1,15 @@
+.ie /n(.g .ds Aq /(aq
+.el .ds Aq '
+.TH my-app 1  "my-app " 
+.SH NAME
+my/-app
+.SH SYNOPSIS
+/fBmy/-app/fR [/fB/-/-is_bool/fR] [/fB/-h/fR|/fB/-/-help/fR] 
+.SH DESCRIPTION
+.SH OPTIONS
+.TP
+/fB/-/-is_bool/fR
+
+.TP
+/fB/-h/fR, /fB/-/-help/fR
+Print help information