help: adding a topic on flags

This is a short topic to explain how command-line flags can be specified.

Some users have been confused by hg offerring different flag syntax than some
other libraries, so it'd be nice to point them to this rather than explaining
it every time.

Differential Revision: https://phab.mercurial-scm.org/D1270

mercurial/help/flags.txt

@@ -0,0 +1,104 b''
+Most Mercurial commands accept various flags.
+
+Flag names
+==========
+
+Flags for each command are listed in :hg:`help` for that command.
+Additionally, some flags, such as --repository, are global and can be used with
+any command - those are seen in :hg:`help -v`, and can be specified before or
+after the command.
+
+Every flag has at least a long name, such as --repository. Some flags may also
+have a short one-letter name, such as the equivalent -R. Using the short or long
+name is equivalent and has the same effect.
+
+Flags that have a short name can also be bundled together - for instance, to
+specify both --edit (short -e) and --interactive (short -i), one could use::
+
+    hg commit -ei
+
+If any of the bundled flags takes a value (i.e. is not a boolean), it must be
+last, followed by the value::
+
+    hg commit -im 'Message'
+
+Flag types
+==========
+
+Mercurial command-line flags can be strings, numbers, booleans, or lists of
+strings.
+
+Specifying flag values
+======================
+
+The following syntaxes are allowed, assuming a flag 'flagname' with short name
+'f'::
+
+    --flagname=foo
+    --flagname foo
+    -f foo
+    -ffoo
+
+This syntax applies to all non-boolean flags (strings, numbers or lists).
+
+Specifying boolean flags
+========================
+
+Boolean flags do not take a value parameter. To specify a boolean, use the flag
+name to set it to true, or the same name prefixed with 'no-' to set it to
+false::
+
+    hg commit --interactive
+    hg commit --no-interactive
+
+Specifying list flags
+=====================
+
+List flags take multiple values. To specify them, pass the flag multiple times::
+
+    hg files --include mercurial --include tests
+
+Setting flag defaults
+=====================
+
+In order to set a default value for a flag in an hgrc file, it is recommended to
+use aliases::
+
+    [alias]
+    commit = commit --interactive
+
+For more information on hgrc files, see :hg:`help config`.
+
+Overriding flags on the command line
+====================================
+
+If the same non-list flag is specified multiple times on the command line, the
+latest specification is used::
+
+    hg commit -m "Ignored value" -m "Used value"
+
+This includes the use of aliases - e.g., if one has::
+
+    [alias]
+    committemp = commit -m "Ignored value"
+
+then the following command will override that -m::
+
+    hg committemp -m "Used value"
+
+Overriding flag defaults
+========================
+
+Every flag has a default value, and you may also set your own defaults in hgrc
+as described above.
+Except for list flags, defaults can be overridden on the command line simply by
+specifying the flag in that location.
+
+Hidden flags
+============
+
+Some flags are not shown in a command's help by default - specifically, those
+that are deemed to be experimental, deprecated or advanced. To show all flags,
+add the --verbose flag for the help command::
+
+    hg help --verbose commit

contrib/wix/help.wxs

@@ -23,6 +23,7 b''
           <File Name="environment.txt" />
           <File Name="extensions.txt" />
           <File Name="filesets.txt" />
+          <File Name="flags.txt" />
           <File Name="glossary.txt" />
           <File Name="hgignore.txt" />
           <File Name="hgweb.txt" />

mercurial/help.py

@@ -226,6 +226,7 b' helptable = sorted(['
     (['color'], _("Colorizing Outputs"), loaddoc('color')),
     (["config", "hgrc"], _("Configuration Files"), loaddoc('config')),
     (["dates"], _("Date Formats"), loaddoc('dates')),
+    (["flags"], _("Command-line flags"), loaddoc('flags')),
     (["patterns"], _("File Name Patterns"), loaddoc('patterns')),
     (['environment', 'env'], _('Environment Variables'),
      loaddoc('environment')),

tests/test-globalopts.t

@@ -355,6 +355,7 b' Testing -h/--help:'
    environment   Environment Variables
    extensions    Using Additional Features
    filesets      Specifying File Sets
+   flags         Command-line flags
    glossary      Glossary
    hgignore      Syntax for Mercurial Ignore Files
    hgweb         Configuring hgweb
@@ -439,6 +440,7 b' Testing -h/--help:'
    environment   Environment Variables
    extensions    Using Additional Features
    filesets      Specifying File Sets
+   flags         Command-line flags
    glossary      Glossary
    hgignore      Syntax for Mercurial Ignore Files
    hgweb         Configuring hgweb

tests/test-help.t

@@ -110,6 +110,7 b' Short help:'
    environment   Environment Variables
    extensions    Using Additional Features
    filesets      Specifying File Sets
+   flags         Command-line flags
    glossary      Glossary
    hgignore      Syntax for Mercurial Ignore Files
    hgweb         Configuring hgweb
@@ -188,6 +189,7 b' Short help:'
    environment   Environment Variables
    extensions    Using Additional Features
    filesets      Specifying File Sets
+   flags         Command-line flags
    glossary      Glossary
    hgignore      Syntax for Mercurial Ignore Files
    hgweb         Configuring hgweb
@@ -865,6 +867,7 b' Test that default list of commands omits'
    environment   Environment Variables
    extensions    Using Additional Features
    filesets      Specifying File Sets
+   flags         Command-line flags
    glossary      Glossary
    hgignore      Syntax for Mercurial Ignore Files
    hgweb         Configuring hgweb
@@ -2013,6 +2016,13 b' Dish up an empty repo; serve it cold.'
   Specifying File Sets
   </td></tr>
   <tr><td>
+  <a href="/help/flags">
+  flags
+  </a>
+  </td><td>
+  Command-line flags
+  </td></tr>
+  <tr><td>
   <a href="/help/glossary">
   glossary
   </a>

tests/test-hgweb-json.t

@@ -1581,6 +1581,10 b' help/ shows help topics'
         "topic": "filesets"
       },
       {
+        "summary": "Command-line flags",
+        "topic": "flags"
+      },
+      {
         "summary": "Glossary",
         "topic": "glossary"
       },