[v3,1/2] kernel-doc: don't let V=1 change outcome

  From: Johannes Berg <johannes.berg@intel.com>

The kernel-doc script currently reports a number of issues
only in "verbose" mode, but that's initialized from V=1
(via KBUILD_VERBOSE), so if you use KDOC_WERROR=1 then
adding V=1 might actually break the build. This is rather
unexpected.

Change kernel-doc to not change its behaviour wrt. errors
(or warnings) when verbose mode is enabled, but rather add
separate warning flags (and -Wall) for it. Allow enabling
those flags via environment/make variables in the kernel's
build system for easier user use, but to not have to parse
them in the script itself.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
v2: - parse environment variables in build system rather than
      the script itself, as suggested by Masahiro Yamada
    - fix indentation
v3: - use a single KDOCFLAGS variable
---
 Documentation/kbuild/kbuild.rst |  6 ++++++
 scripts/Makefile.build          |  2 +-
 scripts/kernel-doc              | 28 +++++++++++++++++++++++-----
 3 files changed, 30 insertions(+), 6 deletions(-)
  

On Fri, Jun 9, 2023 at 5:46 PM Johannes Berg <johannes@sipsolutions.net> wrote:
>
> From: Johannes Berg <johannes.berg@intel.com>
>
> The kernel-doc script currently reports a number of issues
> only in "verbose" mode, but that's initialized from V=1
> (via KBUILD_VERBOSE), so if you use KDOC_WERROR=1 then
> adding V=1 might actually break the build. This is rather
> unexpected.
>
> Change kernel-doc to not change its behaviour wrt. errors
> (or warnings) when verbose mode is enabled, but rather add
> separate warning flags (and -Wall) for it. Allow enabling
> those flags via environment/make variables in the kernel's
> build system for easier user use, but to not have to parse
> them in the script itself.
>
> Signed-off-by: Johannes Berg <johannes.berg@intel.com>



Applied to linux-kbuild with Jon's Ack.
Thanks.




> ---
> v2: - parse environment variables in build system rather than
>       the script itself, as suggested by Masahiro Yamada
>     - fix indentation
> v3: - use a single KDOCFLAGS variable
> ---
>  Documentation/kbuild/kbuild.rst |  6 ++++++
>  scripts/Makefile.build          |  2 +-
>  scripts/kernel-doc              | 28 +++++++++++++++++++++++-----
>  3 files changed, 30 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/kbuild/kbuild.rst b/Documentation/kbuild/kbuild.rst
> index 2a22ddb1b848..bd906407e307 100644
> --- a/Documentation/kbuild/kbuild.rst
> +++ b/Documentation/kbuild/kbuild.rst
> @@ -150,6 +150,12 @@ the UTS_MACHINE variable, and on some architectures also the kernel config.
>  The value of KBUILD_DEBARCH is assumed (not checked) to be a valid Debian
>  architecture.
>
> +KDOCFLAGS
> +---------
> +Specify extra (warning/error) flags for kernel-doc checks during the build,
> +see scripts/kernel-doc for which flags are supported. Note that this doesn't
> +(currently) apply to documentation builds.
> +
>  ARCH
>  ----
>  Set ARCH to the architecture to be built.
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 9f94fc83f086..a0b4fb58201c 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -101,7 +101,7 @@ else ifeq ($(KBUILD_CHECKSRC),2)
>  endif
>
>  ifneq ($(KBUILD_EXTRA_WARN),)
> -  cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $<
> +  cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $(KDOCFLAGS) $<
>  endif
>
>  # Compile C sources (.c)
> diff --git a/scripts/kernel-doc b/scripts/kernel-doc
> index 2486689ffc7b..8f8440870a0f 100755
> --- a/scripts/kernel-doc
> +++ b/scripts/kernel-doc
> @@ -23,7 +23,7 @@ kernel-doc - Print formatted kernel documentation to stdout
>
>  =head1 SYNOPSIS
>
> - kernel-doc [-h] [-v] [-Werror]
> + kernel-doc [-h] [-v] [-Werror] [-Wall] [-Wreturn] [-Wshort-description] [-Wcontents-before-sections]
>     [ -man |
>       -rst [-sphinx-version VERSION] [-enable-lineno] |
>       -none
> @@ -133,6 +133,9 @@ my $dohighlight = "";
>
>  my $verbose = 0;
>  my $Werror = 0;
> +my $Wreturn = 0;
> +my $Wshort_desc = 0;
> +my $Wcontents_before_sections = 0;
>  my $output_mode = "rst";
>  my $output_preformatted = 0;
>  my $no_doc_sections = 0;
> @@ -187,9 +190,14 @@ if (defined($ENV{'KCFLAGS'})) {
>         }
>  }
>
> +# reading this variable is for backwards compat just in case
> +# someone was calling it with the variable from outside the
> +# kernel's build system
>  if (defined($ENV{'KDOC_WERROR'})) {
>         $Werror = "$ENV{'KDOC_WERROR'}";
>  }
> +# other environment variables are converted to command-line
> +# arguments in cmd_checkdoc in the build system
>
>  # Generated docbook code is inserted in a template at a point where
>  # docbook v3.1 requires a non-zero sequence of RefEntry's; see:
> @@ -318,6 +326,16 @@ while ($ARGV[0] =~ m/^--?(.*)/) {
>         $verbose = 1;
>      } elsif ($cmd eq "Werror") {
>         $Werror = 1;
> +    } elsif ($cmd eq "Wreturn") {
> +       $Wreturn = 1;
> +    } elsif ($cmd eq "Wshort-desc") {
> +       $Wshort_desc = 1;
> +    } elsif ($cmd eq "Wcontents-before-sections") {
> +       $Wcontents_before_sections = 1;
> +    } elsif ($cmd eq "Wall") {
> +        $Wreturn = 1;
> +        $Wshort_desc = 1;
> +        $Wcontents_before_sections = 1;
>      } elsif (($cmd eq "h") || ($cmd eq "help")) {
>                 pod2usage(-exitval => 0, -verbose => 2);
>      } elsif ($cmd eq 'no-doc-sections') {
> @@ -1748,9 +1766,9 @@ sub dump_function($$) {
>      # This check emits a lot of warnings at the moment, because many
>      # functions don't have a 'Return' doc section. So until the number
>      # of warnings goes sufficiently down, the check is only performed in
> -    # verbose mode.
> +    # -Wreturn mode.
>      # TODO: always perform the check.
> -    if ($verbose && !$noret) {
> +    if ($Wreturn && !$noret) {
>             check_return_section($file, $declaration_name, $return_type);
>      }
>
> @@ -2054,7 +2072,7 @@ sub process_name($$) {
>             $state = STATE_NORMAL;
>         }
>
> -       if (($declaration_purpose eq "") && $verbose) {
> +       if (($declaration_purpose eq "") && $Wshort_desc) {
>             emit_warning("${file}:$.", "missing initial short description on line:\n$_");
>         }
>
> @@ -2103,7 +2121,7 @@ sub process_body($$) {
>         }
>
>         if (($contents ne "") && ($contents ne "\n")) {
> -           if (!$in_doc_sect && $verbose) {
> +           if (!$in_doc_sect && $Wcontents_before_sections) {
>                 emit_warning("${file}:$.", "contents before sections\n");
>             }
>             dump_section($file, $section, $contents);
> --
> 2.40.1
>