sys-devel/gcc: backport C23 fix to 15.0.0_pre20241117

Backport a -std=gnu23/-std=c23 fix to 15.0.0_pre20241117 which prevented
coersion from _Bool to NULL. Note that this is still dodgy code and some
are proposing this be banned in a future C version (maybe even C2y), but
it shouldn't be rejected in this version at least.

I've added Closes tags for all bugs which, at a glance, look related,
but I haven't re-tested them all and one or two might need reopening.

Bug: https://gcc.gnu.org/PR112556
Closes: https://bugs.gentoo.org/943862
Closes: https://bugs.gentoo.org/943861
Closes: https://bugs.gentoo.org/943843
Closes: https://bugs.gentoo.org/943811
Closes: https://bugs.gentoo.org/943809
Closes: https://bugs.gentoo.org/943753
Closes: https://bugs.gentoo.org/943715
Closes: https://bugs.gentoo.org/943704
Closes: https://bugs.gentoo.org/942958
Signed-off-by: Sam James <sam@gentoo.org>

2 files changed, 298 insertions, 0 deletions

diff --git a/sys-devel/gcc/files/gcc-15.0.0_pre20241117-PR112556-c-Allow-bool-and-enum-null-pointer-constants.patch b/sys-devel/gcc/files/gcc-15.0.0_pre20241117-PR112556-c-Allow-bool-and-enum-null-pointer-constants.patch
new file mode 100644
index 000000000000..b17c1e04998c
--- /dev/null
+++ b/sys-devel/gcc/files/gcc-15.0.0_pre20241117-PR112556-c-Allow-bool-and-enum-null-pointer-constants.patch
@@ -0,0 +1,244 @@
+From 3d525fce70fa0ffa0b22af6e213643e1ceca5ab5 Mon Sep 17 00:00:00 2001
+Message-ID: <3d525fce70fa0ffa0b22af6e213643e1ceca5ab5.1731987909.git.sam@gentoo.org>
+From: Joseph Myers <josmyers@redhat.com>
+Date: Mon, 18 Nov 2024 22:24:48 +0000
+Subject: [PATCH] c: Allow bool and enum null pointer constants [PR112556]
+
+As reported in bug 112556, GCC wrongly rejects conversion of null
+pointer constants with bool or enum type to pointers in
+convert_for_assignment (assignment, initialization, argument passing,
+return).  Fix the code there to allow BOOLEAN_TYPE and ENUMERAL_TYPE;
+it already allowed INTEGER_TYPE and BITINT_TYPE.
+
+This bug (together with -std=gnu23 meaning false has type bool rather
+than int) has in turn resulted in people thinking they need to fix
+code using false as a null pointer constant for C23 compatibility.
+While such a usage is certainly questionable, it has nothing to do
+with C23 compatibility and the right place for warnings about such
+usage is -Wzero-as-null-pointer-constant.  I think it would be
+appropriate to extend -Wzero-as-null-pointer-constant to cover
+BOOLEAN_TYPE, ENUMERAL_TYPE and BITINT_TYPE (in all the various
+contexts in which that option generates warnings), though this patch
+doesn't do anything about that option.
+
+Bootstrapped with no regressions for x86-64-pc-linux-gnu.
+
+	PR c/112556
+
+gcc/c/
+	* c-typeck.cc (convert_for_assignment): Allow conversion of
+	ENUMERAL_TYPE and BOOLEAN_TYPE null pointer constants to pointers.
+
+gcc/testsuite/
+	* gcc.dg/c11-null-pointer-constant-1.c,
+	gcc.dg/c23-null-pointer-constant-1.c: New tests.
+---
+ gcc/c/c-typeck.cc                             |   2 +
+ .../gcc.dg/c11-null-pointer-constant-1.c      |  55 ++++++++
+ .../gcc.dg/c23-null-pointer-constant-1.c      | 120 ++++++++++++++++++
+ 3 files changed, 177 insertions(+)
+ create mode 100644 gcc/testsuite/gcc.dg/c11-null-pointer-constant-1.c
+ create mode 100644 gcc/testsuite/gcc.dg/c23-null-pointer-constant-1.c
+
+diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
+index 26ee0ebf91f0..a701dd090fb8 100644
+--- a/gcc/c/c-typeck.cc
++++ b/gcc/c/c-typeck.cc
+@@ -8457,6 +8457,8 @@ convert_for_assignment (location_t location, location_t expr_loc, tree type,
+     }
+   else if (codel == POINTER_TYPE
+ 	   && (coder == INTEGER_TYPE
++	       || coder == ENUMERAL_TYPE
++	       || coder == BOOLEAN_TYPE
+ 	       || coder == NULLPTR_TYPE
+ 	       || coder == BITINT_TYPE))
+     {
+diff --git a/gcc/testsuite/gcc.dg/c11-null-pointer-constant-1.c b/gcc/testsuite/gcc.dg/c11-null-pointer-constant-1.c
+new file mode 100644
+index 000000000000..f463a1a59da3
+--- /dev/null
++++ b/gcc/testsuite/gcc.dg/c11-null-pointer-constant-1.c
+@@ -0,0 +1,55 @@
++/* Test zero with different types as null pointer constant: bug 112556.  */
++/* { dg-do compile } */
++/* { dg-options "-std=c11 -pedantic-errors -Wno-pointer-compare" } */
++
++enum e { ZERO };
++
++void *p1 = 0;
++void *p2 = 0LL;
++void *p3 = (char) 0;
++void *p4 = 0UL;
++void *p5 = (_Bool) 0;
++void *p6 = (enum e) ZERO;
++
++void f (void *);
++
++void *
++g (void)
++{
++  p1 = 0;
++  p2 = 0LL;
++  p3 = (char) 0;
++  p4 = 0UL;
++  p5 = (_Bool) 0;
++  p6 = (enum e) ZERO;
++  f (0);
++  f (0ULL);
++  f (0L);
++  f ((char) 0);
++  f ((_Bool) 0);
++  f ((enum e) ZERO);
++  (1 ? p1 : 0);
++  (1 ? p1 : 0L);
++  (1 ? p1 : 0ULL);
++  (1 ? p1 : (char) 0);
++  (1 ? p1 : (_Bool) 0);
++  (1 ? p1 : (enum e) 0);
++  p1 == 0;
++  p1 == 0LL;
++  p1 == 0U;
++  p1 == (char) 0;
++  p1 == (_Bool) 0;
++  p1 == (enum e) 0;
++  p1 != 0;
++  p1 != 0LL;
++  p1 != 0U;
++  p1 != (char) 0;
++  p1 != (_Bool) 0;
++  p1 != (enum e) 0;
++  return 0;
++  return 0UL;
++  return 0LL;
++  return (char) 0;
++  return (_Bool) 0;
++  return (enum e) 0;
++}
+diff --git a/gcc/testsuite/gcc.dg/c23-null-pointer-constant-1.c b/gcc/testsuite/gcc.dg/c23-null-pointer-constant-1.c
+new file mode 100644
+index 000000000000..71b66cc35d6b
+--- /dev/null
++++ b/gcc/testsuite/gcc.dg/c23-null-pointer-constant-1.c
+@@ -0,0 +1,120 @@
++/* Test zero with different types as null pointer constant: bug 112556.  */
++/* { dg-do compile } */
++/* { dg-options "-std=c23 -pedantic-errors -Wno-pointer-compare" } */
++
++enum e { ZERO };
++enum e2 : bool { BZERO };
++enum e3 : long { LZERO };
++
++void *p1 = 0;
++void *p2 = 0LL;
++void *p3 = (char) 0;
++void *p4 = 0UL;
++void *p5 = (bool) 0;
++void *p6 = (enum e) ZERO;
++void *p7 = false;
++void *p8 = BZERO;
++void *p9 = (enum e2) 0;
++void *p10 = LZERO;
++void *p11 = (enum e3) 0;
++#ifdef __BITINT_MAXWIDTH__
++void *p12 = 0wb;
++void *p13 = 0uwb;
++#endif
++
++void f (void *);
++
++void *
++g (void)
++{
++  p1 = 0;
++  p2 = 0LL;
++  p3 = (char) 0;
++  p4 = 0UL;
++  p5 = (bool) 0;
++  p6 = (enum e) ZERO;
++  p7 = false;
++  p8 = BZERO;
++  p9 = (enum e2) 0;
++  p10 = LZERO;
++  p11 = (enum e3) 0;
++#ifdef __BITINT_MAXWIDTH__
++  p12 = 0wb;
++  p13 = 0uwb;
++#endif
++  f (0);
++  f (0ULL);
++  f (0L);
++  f ((char) 0);
++  f ((bool) 0);
++  f ((enum e) ZERO);
++  f (false);
++  f (BZERO);
++  f ((enum e2) 0);
++  f (LZERO);
++  f ((enum e3) 0);
++#ifdef __BITINT_MAXWIDTH__
++  f (0wb);
++  f (0uwb);
++#endif
++  (1 ? p1 : 0);
++  (1 ? p1 : 0L);
++  (1 ? p1 : 0ULL);
++  (1 ? p1 : (char) 0);
++  (1 ? p1 : (bool) 0);
++  (1 ? p1 : (enum e) 0);
++  (1 ? p1 : false);
++  (1 ? p1 : BZERO);
++  (1 ? p1 : (enum e2) 0);
++  (1 ? p1 : LZERO);
++  (1 ? p1 : (enum e3) 0);
++#ifdef __BITINT_MAXWIDTH__
++  (1 ? p1 : 0wb);
++  (1 ? p1 : 0uwb);
++#endif
++  p1 == 0;
++  p1 == 0LL;
++  p1 == 0U;
++  p1 == (char) 0;
++  p1 == (bool) 0;
++  p1 == (enum e) 0;
++  p1 == false;
++  p1 == BZERO;
++  p1 == (enum e2) 0;
++  p1 == LZERO;
++  p1 == (enum e3) 0;
++#ifdef __BITINT_MAXWIDTH__
++  p1 == 0wb;
++  p1 == 0uwb;
++#endif
++  p1 != 0;
++  p1 != 0LL;
++  p1 != 0U;
++  p1 != (char) 0;
++  p1 != (bool) 0;
++  p1 != (enum e) 0;
++  p1 != false;
++  p1 != BZERO;
++  p1 != (enum e2) 0;
++  p1 != LZERO;
++  p1 != (enum e3) 0;
++#ifdef __BITINT_MAXWIDTH__
++  p1 != 0wb;
++  p1 != 0uwb;
++#endif
++  return 0;
++  return 0UL;
++  return 0LL;
++  return (char) 0;
++  return (bool) 0;
++  return (enum e) 0;
++  return false;
++  return BZERO;
++  return (enum e2) 0;
++  return LZERO;
++  return (enum e3) 0;
++#ifdef __BITINT_MAXWIDTH__
++  return 0wb;
++  return 0uwb;
++#endif
++}
+-- 
+2.47.0
diff --git a/sys-devel/gcc/gcc-15.0.0_pre20241117-r2.ebuild b/sys-devel/gcc/gcc-15.0.0_pre20241117-r2.ebuild
new file mode 100644
index 000000000000..ee327823124e
--- /dev/null
+++ b/sys-devel/gcc/gcc-15.0.0_pre20241117-r2.ebuild
@@ -0,0 +1,54 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+TOOLCHAIN_PATCH_DEV="sam"
+TOOLCHAIN_HAS_TESTS=1
+PATCH_GCC_VER="15.0.0"
+PATCH_VER="26"
+MUSL_VER="2"
+MUSL_GCC_VER="15.0.0"
+PYTHON_COMPAT=( python3_{10..12} )
+
+if [[ -n ${TOOLCHAIN_GCC_RC} ]] ; then
+	# Cheesy hack for RCs
+	MY_PV=$(ver_cut 1).$((($(ver_cut 2) + 1))).$((($(ver_cut 3) - 1)))-RC-$(ver_cut 5)
+	MY_P=${PN}-${MY_PV}
+	GCC_TARBALL_SRC_URI="mirror://gcc/snapshots/${MY_PV}/${MY_P}.tar.xz"
+	TOOLCHAIN_SET_S=no
+	S="${WORKDIR}"/${MY_P}
+fi
+
+inherit toolchain
+
+if tc_is_live ; then
+	# Needs to be after inherit (for now?), bug #830908
+	EGIT_BRANCH=master
+elif [[ -z ${TOOLCHAIN_USE_GIT_PATCHES} ]] ; then
+	# Don't keyword live ebuilds
+	#KEYWORDS="~alpha ~amd64 ~arm ~arm64 ~hppa ~loong ~m68k ~mips ~ppc ~ppc64 ~riscv ~s390 ~sparc ~x86"
+	:;
+fi
+
+if [[ ${CATEGORY} != cross-* ]] ; then
+	# Technically only if USE=hardened *too* right now, but no point in complicating it further.
+	# If GCC is enabling CET by default, we need glibc to be built with support for it.
+	# bug #830454
+	RDEPEND="elibc_glibc? ( sys-libs/glibc[cet(-)?] )"
+	DEPEND="${RDEPEND}"
+fi
+
+src_prepare() {
+	local p upstreamed_patches=(
+		# add them here
+	)
+	for p in "${upstreamed_patches[@]}"; do
+		rm -v "${WORKDIR}/patch/${p}" || die
+	done
+
+	toolchain_src_prepare
+
+	eapply "${FILESDIR}"/${P}-PR112556-c-Allow-bool-and-enum-null-pointer-constants.patch
+	eapply_user
+}