style: Add '--styling' option.

* guix/scripts/style.scm (format-package-definition): New procedure.
(%options, show-help): Add "--styling".
(%default-options): Add 'styling-procedure'.
(guix-style): Honor it.
* tests/style.scm (with-test-package)
("input labels, 'safe' policy")
("input labels, 'safe' policy, nothing changed")
("input labels, margin comment")
("input labels, margin comment on long list")
("input labels, line comment")
("input labels, modify-inputs and margin comment"): Pass "-S inputs".
* etc/indent-code.el: Remove.
* doc/contributing.texi (Formatting Code): Mention "guix style" instead
of "etc/indent-code.el".
(Submitting Patches): Add item for "guix style".
* doc/guix.texi (Invoking guix style): Document "-S" and update.

2 files changed, 59 insertions, 19 deletions

diff --git a/doc/contributing.texi b/doc/contributing.texi
index 72f5ce1e0e..9f97788c0b 100644
--- a/doc/contributing.texi
+++ b/doc/contributing.texi
@@ -959,17 +959,11 @@ If you do not use Emacs, please make sure to let your editor knows these
 rules.  To automatically indent a package definition, you can also run:
 
 @example
-./etc/indent-code.el gnu/packages/@var{file}.scm @var{package}
+./pre-inst-env guix style @var{package}
 @end example
 
 @noindent
-This automatically indents the definition of @var{package} in
-@file{gnu/packages/@var{file}.scm} by running Emacs in batch mode.  To
-indent a whole file, omit the second argument:
-
-@example
-./etc/indent-code.el gnu/services/@var{file}.scm
-@end example
+@xref{Invoking guix style}, for more information.
 
 @cindex Vim, Scheme code editing
 If you are editing code with Vim, we recommend that you run @code{:set
@@ -1039,6 +1033,10 @@ name of the new or modified package, and fix any errors it reports
 (@pxref{Invoking guix lint}).
 
 @item
+Run @code{guix style @var{package}} to format the new package definition
+according to the project's conventions (@pxref{Invoking guix style}).
+
+@item
 Make sure the package builds on your platform, using @code{guix build
 @var{package}}.
 
@@ -1175,8 +1173,8 @@ Examples of unrelated changes include the addition of several packages,
 or a package update along with fixes to that package.
 
 @item
-Please follow our code formatting rules, possibly running the
-@command{etc/indent-code.el} script to do that automatically for you
+Please follow our code formatting rules, possibly running
+@command{guix style} script to do that automatically for you
 (@pxref{Formatting Code}).
 
 @item
diff --git a/doc/guix.texi b/doc/guix.texi
index 601212fb45..7ffb0d738c 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -12785,8 +12785,16 @@ otherwise.
 
 The @command{guix style} command helps packagers style their package
 definitions according to the latest fashionable trends.  The command
-currently focuses on one aspect: the style of package inputs.  It may
-eventually be extended to handle other stylistic matters.
+currently provides the providing styling rules:
+
+@itemize
+@item
+formatting package definitions according to the project's conventions
+(@pxref{Formatting Code});
+
+@item
+rewriting package inputs to the ``new style'', as explained below.
+@end itemize
 
 The way package inputs are written is going through a transition
 (@pxref{package Reference}, for more on package inputs).  Until version
@@ -12817,7 +12825,7 @@ Package Variants}, for more info on @code{modify-inputs}).
 
 In the vast majority of cases, this is a purely mechanical change on the
 surface syntax that does not even incur a package rebuild.  Running
-@command{guix style} can do that for you, whether you're working on
+@command{guix style -S inputs} can do that for you, whether you're working on
 packages in Guix proper or in an external channel.
 
 The general syntax is:
@@ -12827,15 +12835,48 @@ guix style [@var{options}] @var{package}@dots{}
 @end example
 
 This causes @command{guix style} to analyze and rewrite the definition
-of @var{package}@dots{}.  It does so in a conservative way: preserving
-comments and bailing out if it cannot make sense of the code that
-appears in an inputs field.  The available options are listed below.
+of @var{package}@dots{} or, when @var{package} is omitted, of @emph{all}
+the packages.  The @option{--styling} or @option{-S} option allows you
+to select the style rule, the default rule being @code{format}---see
+below.
+
+The available options are listed below.
 
 @table @code
 @item --dry-run
 @itemx -n
 Show source file locations that would be edited but do not modify them.
 
+@item --styling=@var{rule}
+@itemx -S @var{rule}
+Apply @var{rule}, one of the following styling rules:
+
+@table @code
+@item format
+Format the given package definition(s)---this is the default styling
+rule.  For example, a packager running Guix on a checkout
+(@pxref{Running Guix Before It Is Installed}) might want to reformat the
+definition of the Coreutils package like so:
+
+@example
+./pre-inst-env guix style coreutils
+@end example
+
+@item inputs
+Rewrite package inputs to the ``new style'', as described above.  This
+is how you would rewrite inputs of package @code{whatnot} in your own
+channel:
+
+@example
+guix style -L ~/my/channel -S inputs whatnot
+@end example
+
+Rewriting is done in a conservative way: preserving comments and bailing
+out if it cannot make sense of the code that appears in an inputs field.
+The @option{--input-simplification} option described below provides
+fine-grain control over when inputs should be simplified.
+@end table
+
 @item --load-path=@var{directory}
 @itemx -L @var{directory}
 Add @var{directory} to the front of the package module search path
@@ -12854,9 +12895,10 @@ guix style -e '(@@ (gnu packages gcc) gcc-5)'
 styles the @code{gcc-5} package definition.
 
 @item --input-simplification=@var{policy}
-Specify the package input simplification policy for cases where an input
-label does not match the corresponding package name.  @var{policy} may
-be one of the following:
+When using the @code{inputs} styling rule, with @samp{-S inputs}, this
+option specifies the package input simplification policy for cases where
+an input label does not match the corresponding package name.
+@var{policy} may be one of the following:
 
 @table @code
 @item silent