Apply upstream patches to fix C99 compatibility issue

Related to:

  <https://fedoraproject.org/wiki/Changes/PortingToModernC>
  <https://fedoraproject.org/wiki/Toolchain/PortingToModernC>

radvd-c99-1.patch

@@ -0,0 +1,31 @@
+commit ff7ab0cf445236f30e58531175ba912614fed952
+Author: Sam James <sam@gentoo.org>
+Date:   Thu Nov 17 22:03:25 2022 +0000
+
+    Makefile.am: drop -Wno-implicit-function-declaration
+    
+    1. Clang 16 makes -Wimplicit-function-declaration error by default
+       (and it's planned that GCC 14 will do the same) so we need to fix
+       the real problem. This is papering over it.
+    
+    2. It's not true that there's nothing we can do about it. Fix in a follow-up
+       commit.
+    
+    Bug: https://bugs.gentoo.org/880823
+    Fixes: b5e6b09cf914a960ac3b1676b77d3ea9f91821c7
+    Signed-off-by: Sam James <sam@gentoo.org>
+
+diff --git a/Makefile.am b/Makefile.am
+index 3a52e3a4abab088b..88b0c3514d265524 100644
+--- a/Makefile.am
++++ b/Makefile.am
+@@ -66,9 +66,6 @@ radvd_LDADD = \
+ scanner.c: gram.h
+ gram.h: gram.c
+ 
+-libradvd_parser_a_CFLAGS = \
+-	-Wno-implicit-function-declaration
+-
+ libradvd_parser_a_SOURCES = \
+ 	gram.h \
+ 	gram.y \

radvd-c99-2.patch

@@ -0,0 +1,34 @@
+commit e0f5bcd9091a5f7abd423fce9f372c8079849a64
+Author: Sam James <sam@gentoo.org>
+Date:   Thu Nov 17 22:03:25 2022 +0000
+
+    gram.y: Fix -Wimplicit-function-declaration
+    
+    Clang 16 makes -Wimplicit-function-declaration an error by default.
+    
+    For more information, see LWN.net [0] or LLVM's Discourse [1], the Gentoo wiki [2],
+    or the (new) c-std-porting mailing list [3].
+    
+    [0] https://lwn.net/Articles/913505/
+    [1] https://discourse.llvm.org/t/configure-script-breakage-with-the-new-werror-implicit-function-declaration/65213
+    [2] https://wiki.gentoo.org/wiki/Modern_C_porting
+    [3] hosted at lists.linux.dev.
+    
+    Bug: https://bugs.gentoo.org/880823
+    Signed-off-by: Sam James <sam@gentoo.org>
+
+diff --git a/gram.y b/gram.y
+index 4115390c249ab62b..2b142125e9dd05ae 100644
+--- a/gram.y
++++ b/gram.y
+@@ -20,6 +20,10 @@
+ 
+ #define YYERROR_VERBOSE 1
+ 
++int yylex (void);
++void yyset_in (FILE * _in_str);
++int yylex_destroy (void);
++
+ #if 0 /* no longer necessary? */
+ #ifndef HAVE_IN6_ADDR_S6_ADDR
+ # ifdef __FreeBSD__

radvd.spec

@@ -1,13 +1,15 @@
 Summary: A Router Advertisement daemon
 Name: radvd
 Version: 2.19
-Release: 7%{?dist}
+Release: 8%{?dist}
 
 # The code includes the advertising clause, so it's GPL-incompatible
 License: BSD with advertising
 URL: http://www.litech.org/radvd/
 Source0: %{url}dist/%{name}-%{version}.tar.xz
 Source1: radvd.sysusers
+Patch0: radvd-c99-1.patch
+Patch1: radvd-c99-2.patch
 
 BuildRequires: make
 BuildRequires: gcc
@@ -20,6 +22,8 @@ BuildRequires: systemd
 BuildRequires: systemd-rpm-macros
 %{?systemd_requires}
 %{?sysusers_requires_compat}
+BuildRequires: autoconf
+BuildRequires: automake
 
 %description
 radvd is the router advertisement daemon for IPv6.  It listens to router
@@ -42,6 +46,7 @@ for F in CHANGES; do
 done
 
 %build
+autoreconf -iv
 export CFLAGS="$RPM_OPT_FLAGS -fPIE " 
 export LDFLAGS='-pie -Wl,-z,relro,-z,now,-z,noexecstack,-z,nodlopen'
 %configure \
@@ -94,6 +99,10 @@ make check
 %{_sbindir}/radvdump
 
 %changelog
+* Thu Dec 22 2022 Florian Weimer <fweimer@redhat.com> - 2.19-8
+- Apply upstream patches to fix C99 compatibility issue
+- Run autoconf/automake during the build
+
 * Thu Nov 03 2022 Martin Osvald <mosvald@redhat.com> - 2.19-7
 - Use systemd-sysusers for radvd user and group (rhbz#2139755)