sys-devel/flex: backport further macro fixes

The gist is that the original glibc-2.26 patch was incomplete
and didn't help with cross-compilation or non-glibc environments
fully.

There were a succession of further upstream commits
now backported here. Noticed when doing some more Clang 16 work.

This complements bec6a7be57fc3493dccef497b5d4b513c315f5f1 in that
more effort is taken to ensure all necessary macros are defined
so needed functions are available.

Bug: https://bugs.gentoo.org/628744
Bug: https://bugs.gentoo.org/705800
See: bec6a7be57fc3493dccef497b5d4b513c315f5f1
See: 4d77781e2db7bb8bef7f390c43efc04ba58ff7bb
See: aa6c077d00c3a21b75ae646421aefadcad527f80
Signed-off-by: Sam James <sam@gentoo.org>

3 files changed, 233 insertions, 8 deletions

diff --git a/sys-devel/flex/Manifest b/sys-devel/flex/Manifest
index 0e5c2985d561..34ccf066269d 100644
--- a/sys-devel/flex/Manifest
+++ b/sys-devel/flex/Manifest
@@ -1,2 +1,2 @@
-DIST flex-2.6.4-implicit-func-decl.patch.xz 6572 BLAKE2B 7b2eb1d240e46470c4899b667fc6fbb1d0f91d784d67bb47f351c35683bda4d3c5d59479a8a26f1d9250fd9f6ce9e8b77ee7c53183c09735e898b48cd74bcb88 SHA512 cf7e5ac35b617b40ac3ca3dcf5c5ec5e81a1a48b99348c646aa68f61f3a83cbda3c9a6e820ad275f994220a6290518c4f56bdba9c0ed303cf27e60a75f4eb88c
+DIST flex-2.6.4-autotools-regenerate.patch.xz 282588 BLAKE2B 3995b8b5e354a43b1a4ff72fae76027c904ddb24eb8e5d55fc6fbe81299f48fa70ac3c4a98b9ed39aca8a98190d6db5005cacb96ec1016d413860d84a434dcc0 SHA512 9efd3197fdf7f8435dfbf4dafbe6b99c1fafede0ec364dbeb9cca81711763d693bc5d30fc3b2af038a44f8848577d19dd737e3afe0cd3b08ab79daea64fcdefa
 DIST flex-2.6.4.tar.gz 1419096 BLAKE2B c003d4f764f7f4d41e33af7ee28c2af272a9f0aee6ba7c2494ba96722d8d0b18f7a3f745217e9a2cecb43b6863328267a810280670c04464156b3eb3d7ee9d62 SHA512 e9785f3d620a204b7d20222888917dc065c2036cae28667065bf7862dfa1b25235095a12fd04efdbd09bfd17d3452e6b9ef953a8c1137862ff671c97132a082e
diff --git a/sys-devel/flex/files/flex-2.6.4-fix-build-with-glibc2.26.patch b/sys-devel/flex/files/flex-2.6.4-fix-build-with-glibc2.26.patch
new file mode 100644
index 000000000000..9a9de8746b89
--- /dev/null
+++ b/sys-devel/flex/files/flex-2.6.4-fix-build-with-glibc2.26.patch
@@ -0,0 +1,219 @@
+https://github.com/westes/flex/issues/436
+https://bugs.gentoo.org/705800
+https://developers.redhat.com/blog/2019/04/22/implicit-function-declarations-flexs-use-of-reallocarray
+https://github.com/westes/flex/commit/4b5111d9772b5c160340ca96f08d30d7f6db5cda
+https://github.com/westes/flex/commit/24fd0551333e7eded87b64dd36062da3df2f6380
+https://github.com/westes/flex/commit/0db9f8903a446e7026874be519b8dc55a471f014
+https://github.com/westes/flex/commit/a17d79e9c722a6735b6d2a8f152287404f27df32
+https://github.com/westes/flex/commit/4081efa0831b15d7e4e4255401c225ad8262426d
+https://github.com/westes/flex/commit/1985bb3c7abed940e91ad816504ef08a18c3b7c1
+
+From 4b5111d9772b5c160340ca96f08d30d7f6db5cda Mon Sep 17 00:00:00 2001
+From: Explorer09 <explorer09@gmail.com>
+Date: Mon, 4 Sep 2017 08:28:53 +0800
+Subject: [PATCH] scanner: Include flexdef.h at %top block of scan.l
+
+config.h may define macros that alter the API of the standard library
+funtions, and so it should be included before any other standard
+header, even before the skeleton's standard header inclusion.
+
+For example: config.h may #define _GNU_SOURCE that would expose the
+reallocarray() prototype from <stdlib.h> on glibc 2.26+ systems. If we
+include <stdlib.h> before config.h, reallocarray() would not be
+available for use in lex file since the second include doesn't help
+due to header guard.
+
+For now our config.h might `#define malloc rpl_malloc` -- this
+substitution must work before including stdlib.h, or else the compiler
+will complain about missing prototypes, and may result in incorrect
+code in scan.l (gcc warning: return makes pointer from integer without
+a cast [-Wint-conversion]).
+
+Fixes #247.
+--- a/src/scan.l
++++ b/src/scan.l
+@@ -1,5 +1,11 @@
+ /* scan.l - scanner for flex input -*-C-*- */
+ 
++%top{
++/* flexdef.h includes config.h, which may contain macros that alter the API */
++/* of libc functions. Must include first before any libc header. */
++#include "flexdef.h"
++}
++
+ %{
+ /*  Copyright (c) 1990 The Regents of the University of California. */
+ /*  All rights reserved. */
+@@ -32,7 +38,6 @@
+ /*  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR */
+ /*  PURPOSE. */
+ 
+-#include "flexdef.h"
+ #include "parse.h"
+ extern bool tablesverify, tablesext;
+ extern int trlcontxt; /* Set in  parse.y for each rule. */
+
+From 24fd0551333e7eded87b64dd36062da3df2f6380 Mon Sep 17 00:00:00 2001
+From: Explorer09 <explorer09@gmail.com>
+Date: Mon, 4 Sep 2017 10:47:33 +0800
+Subject: [PATCH] build: AC_USE_SYSTEM_EXTENSIONS in configure.ac.
+
+This would, e.g. define _GNU_SOURCE in config.h, enabling the
+reallocarray() prototype in glibc 2.26+ on Linux systems with that
+version of glibc.
+
+Fixes #241.
+--- a/configure.ac
++++ b/configure.ac
+@@ -25,8 +25,10 @@
+ # autoconf requirements and initialization
+ 
+ AC_INIT([the fast lexical analyser generator],[2.6.4],[flex-help@lists.sourceforge.net],[flex])
++AC_PREREQ([2.60])
+ AC_CONFIG_SRCDIR([src/scan.l])
+ AC_CONFIG_AUX_DIR([build-aux])
++AC_USE_SYSTEM_EXTENSIONS
+ LT_INIT
+ AM_INIT_AUTOMAKE([1.15 -Wno-portability foreign std-options dist-lzip parallel-tests subdir-objects])
+ AC_CONFIG_HEADER([src/config.h])
+
+
+From 0db9f8903a446e7026874be519b8dc55a471f014 Mon Sep 17 00:00:00 2001
+From: Lukasz Baj <l.baj@radytek.com>
+Date: Fri, 22 Sep 2017 10:24:46 +0200
+Subject: [PATCH] build: Remove custom reallocarray() declaration.
+
+Use one from <stdlib.h> instead because that is more portable.
+--- a/src/flexdef.h
++++ b/src/flexdef.h
+@@ -631,10 +631,6 @@ extern int sectnum, nummt, hshcol, dfaeql, numeps, eps2, num_reallocs;
+ extern int tmpuses, totnst, peakpairs, numuniq, numdup, hshsave;
+ extern int num_backing_up, bol_needed;
+ 
+-#ifndef HAVE_REALLOCARRAY
+-void *reallocarray(void *, size_t, size_t);
+-#endif
+-
+ void   *allocate_array(int, size_t);
+ void   *reallocate_array(void *, int, size_t);
+ 
+
+From a17d79e9c722a6735b6d2a8f152287404f27df32 Mon Sep 17 00:00:00 2001
+From: Explorer09 <explorer09@gmail.com>
+Date: Sat, 14 Oct 2017 00:36:54 +0800
+Subject: [PATCH] scanner: Define _POSIX_C_SOURCE when needed in skeleton.
+
+The function fileno() is defined by POSIX. When flex would otherwise not provide that feature macro, we define it.
+
+Fixes #263
+--- a/src/flex.skl
++++ b/src/flex.skl
+@@ -218,6 +218,14 @@ m4_ifdef( [[M4_YY_TABLES_EXTERNAL]],
+ 
+ /* begin standard C headers. */
+ %if-c-only
++m4_ifdef( [[M4_YY_ALWAYS_INTERACTIVE]], ,
++[[m4_ifdef( [[M4_YY_NEVER_INTERACTIVE]], ,
++[[#ifndef _POSIX_C_SOURCE
++#define _POSIX_C_SOURCE 1 /* for fileno() */
++#ifndef _POSIX_SOURCE
++#define _POSIX_SOURCE 1
++#endif
++#endif]])]])
+ #include <stdio.h>
+ #include <string.h>
+ #include <errno.h>
+
+From 4081efa0831b15d7e4e4255401c225ad8262426d Mon Sep 17 00:00:00 2001
+From: Explorer09 <explorer09@gmail.com>
+Date: Thu, 8 Mar 2018 10:04:36 +0800
+Subject: [PATCH] scanner: Fix glibc features.h dependency in skeleton.
+
+Commit a17d79e9c722a6735b6d2a8f152287404f27df32 defines _POSIX_C_SOURCE
+to the minimum of 1 if it's not defined in the user's scanner code or
+the compiling environment. However in glibc the macros are not yet set
+up until one of the libc headers is included. This unfortunately have
+made us overwrite the default _POSIX_C_SOURCE value that would be
+defined by glibc (200809L at the time of writing), causing regressions
+in user code.
+
+Now in this patch:
+1. Ensure feature test macros have been set up in glibc before checking
+or defining any of them in our skeleton code.
+2. Have a more conservative logic when determining the need to define
+_POSIX_C_SOURCE (required for fileno()).
+
+Fixes: #313
+
+Note:
+It could be tricky for application code to ensure feature test macros
+have been set up in glibc, since <features.h> is no portable header and
+not meant to be included directly by applications. The way to do it is
+to include a libc header which in turn includes <features.h>. However,
+many of the glibc headers check __USE_POSIX (a glibc internal macro
+defined if _POSIX_C_SOURCE is defined) and determine which interfaces
+to expose already, making the headers inappropriate for our goal.
+Those which don't depend on _POSIX_C_SOURCE, and are also available
+since ANSI C89, are only <assert.h>, <errno.h> and <math.h>.
+
+<assert.h> is finally favored due to other considerations:
+- <math.h> check for __USE_XOPEN in glibc, making a dependency on
+_XOPEN_SOURCE, besides it exposes much more interfaces than we need.
+- In djgpp, <errno.h> depends on _POSIX_SOURCE to hide definitions of
+some errno values when it's defined.
+- <assert.h> exposes the fewest interfaces among the 3 headers and, at
+the time of writing, checks for only C99 (for __func__), C11 (for
+_Static_assert), and _GNU_SOURCE when needed.
+
+Signed-off-by: Kang-Che Sung <explorer09@gmail.com>
+--- a/src/flex.skl
++++ b/src/flex.skl
+@@ -220,11 +220,21 @@ m4_ifdef( [[M4_YY_TABLES_EXTERNAL]],
+ %if-c-only
+ m4_ifdef( [[M4_YY_ALWAYS_INTERACTIVE]], ,
+ [[m4_ifdef( [[M4_YY_NEVER_INTERACTIVE]], ,
+-[[#ifndef _POSIX_C_SOURCE
+-#define _POSIX_C_SOURCE 1 /* for fileno() */
+-#ifndef _POSIX_SOURCE
+-#define _POSIX_SOURCE 1
++[[/* Feature test macros. Flex uses functions that require a minimum set of
++ * macros defined. As defining some macros may hide function declarations that
++ * user code might use, be conservative and respect user's definitions as much
++ * as possible. In glibc, feature test macros may not be all set up until one
++ * of the libc header (that includes <features.h>) is included. This creates
++ * a circular dependency when we check the macros. <assert.h> is the safest
++ * header we can include and does not declare too many functions we don't need.
++ */
++#if !defined(__GNU_LIBRARY__) && defined(__STDC__)
++#include <assert.h>
+ #endif
++#if !(defined(_POSIX_C_SOURCE) || defined(_XOPEN_SOURCE) || \
++    defined(_POSIX_SOURCE))
++# define _POSIX_C_SOURCE 1 /* Required for fileno() */
++# define _POSIX_SOURCE 1
+ #endif]])]])
+ #include <stdio.h>
+ #include <string.h>
+
+From 1985bb3c7abed940e91ad816504ef08a18c3b7c1 Mon Sep 17 00:00:00 2001
+From: Explorer09 <explorer09@gmail.com>
+Date: Thu, 8 Mar 2018 09:53:24 +0800
+Subject: [PATCH] scanner: correct comments about __STDC_LIMIT_MACROS.
+
+No code changes.
+
+Signed-off-by: Kang-Che Sung <explorer09@gmail.com>
+--- a/src/flexint.h
++++ b/src/flexint.h
+@@ -7,8 +7,8 @@
+ 
+ #if defined (__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
+ 
+-/* C99 says to define __STDC_LIMIT_MACROS before including stdint.h,
+- * if you want the limit (max/min) macros for int types. 
++/* C++ systems might need __STDC_LIMIT_MACROS defined before including
++ * <stdint.h>, if you want the limit (max/min) macros for int types.
+  */
+ #ifndef __STDC_LIMIT_MACROS
+ #define __STDC_LIMIT_MACROS 1
+
diff --git a/sys-devel/flex/flex-2.6.4-r3.ebuild b/sys-devel/flex/flex-2.6.4-r4.ebuild
index 1fe2eb9549ec..0fb0e60d9372 100644
--- a/sys-devel/flex/flex-2.6.4-r3.ebuild
+++ b/sys-devel/flex/flex-2.6.4-r4.ebuild
@@ -8,7 +8,7 @@ inherit flag-o-matic libtool multilib-minimal toolchain-funcs
 DESCRIPTION="The Fast Lexical Analyzer"
 HOMEPAGE="https://github.com/westes/flex"
 SRC_URI="https://github.com/westes/${PN}/releases/download/v${PV}/${P}.tar.gz"
-SRC_URI+=" https://dev.gentoo.org/~sam/distfiles/${CATEGORY}/${PN}/${P}-implicit-func-decl.patch.xz"
+SRC_URI+=" https://dev.gentoo.org/~sam/distfiles/${CATEGORY}/${PN}/${P}-autotools-regenerate.patch.xz"
 
 LICENSE="FLEX"
 SLOT="0"
@@ -16,21 +16,27 @@ KEYWORDS="~alpha ~amd64 ~arm ~arm64 ~hppa ~ia64 ~loong ~m68k ~mips ~ppc ~ppc64 ~
 IUSE="nls static test"
 RESTRICT="!test? ( test )"
 
-# We want bison explicitly and not yacc in general, bug #381273
 RDEPEND="sys-devel/m4"
-BDEPEND="${RDEPEND}
+# We want bison explicitly and not yacc in general, bug #381273
+BDEPEND="
+	${RDEPEND}
 	nls? ( sys-devel/gettext )
-	test? ( sys-devel/bison )"
+	test? ( sys-devel/bison )
+"
 
 PATCHES=(
-	"${FILESDIR}"/${PN}-2.6.4-libobjdir.patch
-	"${FILESDIR}"/${PN}-2.6.4-fix-build-with-glibc2.6+.patch
-	"${WORKDIR}"/${P}-implicit-func-decl.patch
+	"${FILESDIR}"/${P}-libobjdir.patch
+	"${FILESDIR}"/${P}-fix-build-with-glibc2.26.patch
+
+	"${WORKDIR}"/${P}-autotools-regenerate.patch
 )
 
 src_prepare() {
 	default
 
+	# Drop on next release when we can remove ${P}-autotools-regenerate.patch
+	touch configure.ac aclocal.m4 Makefile.in configure src/config.h.in || die
+
 	# Disable running in the tests/ subdir as it has a bunch of built sources
 	# that cannot be made conditional (automake limitation). bug #568842
 	if ! use test ; then