style: Add ‘remove-input’ and related styling rules.

* guix/scripts/style.scm (input-matches?, package-list->string,
%field-accessors, remove-from-package-field, transform-package-field):
Add variables.
(%options): Add options --remove-input, --remove-native-input,
--remove-propagated-input, and --parameter.
(guix-style): Implement those options.  To keep ony one autoload, use
specification->package+output rather than specification->package.

* tests/style.scm ("remove-input, single input removed",
"remove-input, one of multiple inputs removed",
"remove-input, middle input removed from list",
"remove-input, non-existent input unchanged",
"remove-input, input with output specifier",
"remove-native-input, single input removed",
"remove-native-input, one of multiple inputs removed",
"remove-native-input, does not affect inputs field",
"remove-propagated-input, single input removed",
"remove-propagated-input, one of multiple inputs removed",
"remove-propagated-input, does not affect other fields",
"remove-input from all three fields independently",
"remove-input, dry-run does not modify file"): New tests.
("url-fetch->git-fetch, preserved field"): Drop the use of %patch-path
and %package-module-path, which are not necessary because of -L.
Change the mocked procedure from specification->package to
specification->package+output, as in the implementation.

* doc/guix.texi (Invoking guix style): Add description for guix style
-S remove-*input rules.

Change-Id: I449c87930310a73ad316b4cb5db72d0906ea495d
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
Merges: #5862

1 files changed, 23 insertions, 0 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 70677e24446..45edf34a78a 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -16137,6 +16137,29 @@ rebuild of the affected packages.  Furthermore, if a package definition
 happens to be using G-expressions already, @command{guix style} leaves
 it unchanged.
 
+@item remove-input
+@itemx remove-native-input
+@itemx remove-propagated-input
+These styling rules remove an input from the given package(s).
+
+Removing these packages respects the package syntax, doesn't affect
+margin comments or parentheses, and will put all remaining inputs on a
+single line if there are less than three.
+
+This is a focused styling rule for use in teams, when updating
+build-systems, or removing unwanted development inputs from
+native-inputs.
+
+To remove package @var{whatnot} from all inputs, use the
+@code{--parameter} option:
+
+@example
+guix style -S remove-input --parameter=@var{whatnot}
+@end example
+
+It is also possible to do that for a collection of packages by appending
+them to the above invocation.
+
 @item git-source
 If the @code{home-page} is a Git repository (as per
 @code{git-repository-url?}), and the actual Git repository is tagged