build: Inline perl prototypes in sources

Prototypes allows us to avoid using the '&foo' invocation form when
invoking a subroutine before its definition.  Previously those
prototypes were generated to prevent them from falling out-of-sync
with actual definitions.  Now we provide a 'check-perl-protos' lint
script to ensure that this is not the case.  This has the same
benefits as generating prototypes while simplifying the
bootstrap/build process.

* bin/gen-perl-protos: Remove.
* bin/Makefile.inc: Adapt.
* bootstrap: Likewise.
* bin/aclocal.in: Inline prototypes.
* bin/automake.in: Likewise.
* maintainer/check-perl-protos: New lint script.
* maintainer/syntax-checks.mk (sc_perl_protos): New target.
(syntax_check_rules): Add it.

2 files changed, 58 insertions, 0 deletions

diff --git a/maintainer/check-perl-protos b/maintainer/check-perl-protos
new file mode 100755
index 000000000..b1d6a72b5
--- /dev/null
+++ b/maintainer/check-perl-protos
@@ -0,0 +1,50 @@
+#!/usr/bin/env perl
+#
+# Copyright (C) 2017 Free Software Foundation, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+use warnings;
+use strict;
+
+my @lines = <>;
+my %forwards = map { /^sub (\w+)\s*\((.*)\);$/ ? ("$1" => "$2") : () } @lines;
+my %subs = map { /^sub (\w+)\s*\((.*)\)$/ ? ("$1" => "$2") : () } @lines;
+my $error_count = 0;
+
+# $subs{"foo"} = "$$";
+# $subs{"bar"} = "@";
+# $forwards{"bar"} = "\$";
+
+# Check that every subroutine has a matching forward declaration with
+# the same prototype.
+foreach my $sub (keys (%subs))
+  {
+    # XXX: The location of the subroutine is not reported.
+    if (grep { $sub eq $_ } keys (%forwards))
+      {
+	if ($forwards{$sub} ne $subs{$sub})
+	  {
+	    $error_count += 1;
+	    warn ("prototype mismatch for \"$sub\" subroutine\n");
+	  }
+      }
+    else
+      {
+	$error_count += 1;
+	warn ("missing prototype for \"$sub\" subroutine\n");
+      }
+  }
+
+exit (($error_count == 0) ? 0 : 1);
diff --git a/maintainer/syntax-checks.mk b/maintainer/syntax-checks.mk
index c8b074008..07a12ab6f 100644
--- a/maintainer/syntax-checks.mk
+++ b/maintainer/syntax-checks.mk
@@ -51,6 +51,7 @@ sc_mkinstalldirs \
 sc_pre_normal_post_install_uninstall \
 sc_perl_no_undef \
 sc_perl_no_split_regex_space \
+sc_perl_protos \
 sc_cd_in_backquotes \
 sc_cd_relative_dir \
 sc_perl_at_uscore_in_scalar_context \
@@ -102,6 +103,13 @@ sc_sanity_gnu_grep:
 .PHONY: sc_sanity_gnu_grep
 $(syntax_check_rules): sc_sanity_gnu_grep
 
+# Check that every subroutine in perl scripts has a corresponding
+# prototype
+sc_perl_protos:
+	$(AM_V_GEN)$(srcdir)/maintainer/check-perl-protos \
+	  <$(srcdir)/bin/aclocal.in && \
+	$(srcdir)/maintainer/check-perl-protos <$(srcdir)/bin/automake.in
+
 # These check avoids accidental configure substitutions in the source.
 # There are exactly 8 lines that should be modified from automake.in to
 # automake, and 9 lines that should be modified from aclocal.in to