sys-devel/clang-common: add maybe-stddefs.h helper

This is needed for musl (and any non-glibc target actually) with Clang, as
GCC adds it by itself (but glibc covers for the compiler even if it doesn't),
but neither Clang nor musl include it by themselves.

See also:
- https://www.openwall.com/lists/musl/2021/04/16/8
- https://reviews.llvm.org/D34158
- https://reviews.llvm.org/D106577
- https://reviews.llvm.org/D137043

Closes: https://bugs.gentoo.org/870001
Signed-off-by: Sam James <sam@gentoo.org>

5 files changed, 230 insertions, 0 deletions

diff --git a/sys-devel/clang-common/clang-common-16.0.3-r1.ebuild b/sys-devel/clang-common/clang-common-16.0.3-r1.ebuild
new file mode 100644
index 000000000000..0d894d8b4232
--- /dev/null
+++ b/sys-devel/clang-common/clang-common-16.0.3-r1.ebuild
@@ -0,0 +1,190 @@
+# Copyright 1999-2023 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit bash-completion-r1 llvm.org
+
+DESCRIPTION="Common files shared between multiple slots of clang"
+HOMEPAGE="https://llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA"
+SLOT="0"
+KEYWORDS="~amd64 ~arm ~arm64 ~loong ~ppc ~ppc64 ~riscv ~sparc ~x86 ~amd64-linux ~ppc-macos ~x64-macos"
+IUSE="
+	default-compiler-rt default-libcxx default-lld llvm-libunwind
+	hardened stricter
+"
+
+PDEPEND="
+	sys-devel/clang:*
+	default-compiler-rt? (
+		sys-devel/clang-runtime[compiler-rt]
+		llvm-libunwind? ( sys-libs/llvm-libunwind[static-libs] )
+		!llvm-libunwind? ( sys-libs/libunwind[static-libs] )
+	)
+	!default-compiler-rt? ( sys-devel/gcc )
+	default-libcxx? ( >=sys-libs/libcxx-${PV} )
+	!default-libcxx? ( sys-devel/gcc )
+	default-lld? ( sys-devel/lld )
+	!default-lld? ( sys-devel/binutils )
+"
+IDEPEND="
+	!default-compiler-rt? ( sys-devel/gcc-config )
+	!default-libcxx? ( sys-devel/gcc-config )
+"
+
+LLVM_COMPONENTS=( clang/utils )
+llvm.org_set_globals
+
+pkg_pretend() {
+	[[ ${CLANG_IGNORE_DEFAULT_RUNTIMES} ]] && return
+
+	local flag missing_flags=()
+	for flag in default-{compiler-rt,libcxx,lld}; do
+		if ! use "${flag}" && has_version "sys-devel/clang[${flag}]"; then
+			missing_flags+=( "${flag}" )
+		fi
+	done
+
+	if [[ ${missing_flags[@]} ]]; then
+		eerror "It seems that you have the following flags set on sys-devel/clang:"
+		eerror
+		eerror "  ${missing_flags[*]}"
+		eerror
+		eerror "The default runtimes are now set via flags on sys-devel/clang-common."
+		eerror "The build is being aborted to prevent breakage.  Please either set"
+		eerror "the respective flags on this ebuild, e.g.:"
+		eerror
+		eerror "  sys-devel/clang-common ${missing_flags[*]}"
+		eerror
+		eerror "or build with CLANG_IGNORE_DEFAULT_RUNTIMES=1."
+		die "Mismatched defaults detected between sys-devel/clang and sys-devel/clang-common"
+	fi
+}
+
+src_install() {
+	newbashcomp bash-autocomplete.sh clang
+
+	insinto /etc/clang
+	newins - gentoo-runtimes.cfg <<-EOF
+		# This file is initially generated by sys-devel/clang-runtime.
+		# It is used to control the default runtimes using by clang.
+
+		--rtlib=$(usex default-compiler-rt compiler-rt libgcc)
+		--unwindlib=$(usex default-compiler-rt libunwind libgcc)
+		--stdlib=$(usex default-libcxx libc++ libstdc++)
+		-fuse-ld=$(usex default-lld lld bfd)
+	EOF
+
+	newins - gentoo-gcc-install.cfg <<-EOF
+		# This file is maintained by gcc-config.
+		# It is used to specify the selected GCC installation.
+	EOF
+
+	newins - gentoo-common.cfg <<-EOF
+		# This file contains flags common to clang, clang++ and clang-cpp.
+		@gentoo-runtimes.cfg
+		@gentoo-gcc-install.cfg
+		@gentoo-hardened.cfg
+		# bug #870001
+		-include "${EPREFIX}/usr/include/gentoo/maybe-stddefs.h"
+	EOF
+
+	# Baseline hardening (bug #851111)
+	newins - gentoo-hardened.cfg <<-EOF
+		# Some of these options are added unconditionally, regardless of
+		# USE=hardened, for parity with sys-devel/gcc.
+		-fstack-clash-protection
+		-fstack-protector-strong
+		-fPIE
+		-include "${EPREFIX}/usr/include/gentoo/fortify.h"
+	EOF
+
+	dodir /usr/include/gentoo
+
+	cat >> "${ED}/usr/include/gentoo/maybe-stddefs.h" <<-EOF || die
+	/* __has_include is an extension, but it's fine, because this is only
+	for Clang anyway. */
+	#if defined __has_include && __has_include (<stdc-predef.h>)
+	# include <stdc-predef.h>
+	#endif
+	EOF
+
+	local fortify_level=$(usex hardened 3 2)
+	# We have to do this because glibc's headers warn if F_S is set
+	# without optimization and that would at the very least be very noisy
+	# during builds and at worst trigger many -Werror builds.
+	cat >> "${ED}/usr/include/gentoo/fortify.h" <<- EOF || die
+	#ifdef __clang__
+	# pragma clang system_header
+	#endif
+	#ifndef _FORTIFY_SOURCE
+	# if defined(__has_feature)
+	#  define __GENTOO_HAS_FEATURE(x) __has_feature(x)
+	# else
+	#  define __GENTOO_HAS_FEATURE(x) 0
+	# endif
+	#
+	# if defined(__OPTIMIZE__) && __OPTIMIZE__ > 0
+	#  if !defined(__SANITIZE_ADDRESS__) && !__GENTOO_HAS_FEATURE(address_sanitizer) && !__GENTOO_HAS_FEATURE(memory_sanitizer)
+	#   define _FORTIFY_SOURCE ${fortify_level}
+	#  endif
+	# endif
+	# undef __GENTOO_HAS_FEATURE
+	#endif
+	EOF
+
+	if use hardened ; then
+		cat >> "${ED}/etc/clang/gentoo-hardened.cfg" <<-EOF || die
+			# Options below are conditional on USE=hardened.
+			-D_GLIBCXX_ASSERTIONS
+
+			# Analogue to GLIBCXX_ASSERTIONS
+			# https://libcxx.llvm.org/UsingLibcxx.html#assertions-mode
+			-D_LIBCPP_ENABLE_ASSERTIONS=1
+		EOF
+	fi
+
+	if use stricter; then
+		newins - gentoo-stricter.cfg <<-EOF
+			# This file increases the strictness of older clang versions
+			# to match the newest upstream version.
+
+			# clang-16 defaults
+			-Werror=implicit-function-declaration
+			-Werror=implicit-int
+			-Werror=incompatible-function-pointer-types
+
+			# constructs banned by C2x
+			-Werror=deprecated-non-prototype
+
+			# deprecated but large blast radius
+			#-Werror=strict-prototypes
+		EOF
+
+		cat >> "${ED}/etc/clang/gentoo-common.cfg" <<-EOF || die
+			@gentoo-stricter.cfg
+		EOF
+	fi
+
+	local tool
+	for tool in clang{,++,-cpp}; do
+		newins - "${tool}.cfg" <<-EOF
+			# This configuration file is used by ${tool} driver.
+			@gentoo-common.cfg
+		EOF
+	done
+}
+
+pkg_preinst() {
+	if has_version -b sys-devel/gcc-config && has_version sys-devel/gcc
+	then
+		local gcc_path=$(gcc-config --get-lib-path 2>/dev/null)
+		if [[ -n ${gcc_path} ]]; then
+			cat >> "${ED}/etc/clang/gentoo-gcc-install.cfg" <<-EOF
+				--gcc-install-dir="${gcc_path%%:*}"
+			EOF
+		fi
+	fi
+}
diff --git a/sys-devel/clang-common/clang-common-16.0.4.9999.ebuild b/sys-devel/clang-common/clang-common-16.0.4.9999.ebuild
index 5b4a6647f3ca..ffae670e7202 100644
--- a/sys-devel/clang-common/clang-common-16.0.4.9999.ebuild
+++ b/sys-devel/clang-common/clang-common-16.0.4.9999.ebuild
@@ -87,6 +87,8 @@ src_install() {
 		@gentoo-runtimes.cfg
 		@gentoo-gcc-install.cfg
 		@gentoo-hardened.cfg
+		# bug #870001
+		-include "${EPREFIX}/usr/include/gentoo/maybe-stddefs.h"
 	EOF
 
 	# Baseline hardening (bug #851111)
@@ -101,6 +103,14 @@ src_install() {
 
 	dodir /usr/include/gentoo
 
+	cat >> "${ED}/usr/include/gentoo/maybe-stddefs.h" <<-EOF || die
+	/* __has_include is an extension, but it's fine, because this is only
+	for Clang anyway. */
+	#if defined __has_include && __has_include (<stdc-predef.h>)
+	# include <stdc-predef.h>
+	#endif
+	EOF
+
 	local fortify_level=$(usex hardened 3 2)
 	# We have to do this because glibc's headers warn if F_S is set
 	# without optimization and that would at the very least be very noisy
diff --git a/sys-devel/clang-common/clang-common-17.0.0.9999.ebuild b/sys-devel/clang-common/clang-common-17.0.0.9999.ebuild
index 5b4a6647f3ca..ffae670e7202 100644
--- a/sys-devel/clang-common/clang-common-17.0.0.9999.ebuild
+++ b/sys-devel/clang-common/clang-common-17.0.0.9999.ebuild
@@ -87,6 +87,8 @@ src_install() {
 		@gentoo-runtimes.cfg
 		@gentoo-gcc-install.cfg
 		@gentoo-hardened.cfg
+		# bug #870001
+		-include "${EPREFIX}/usr/include/gentoo/maybe-stddefs.h"
 	EOF
 
 	# Baseline hardening (bug #851111)
@@ -101,6 +103,14 @@ src_install() {
 
 	dodir /usr/include/gentoo
 
+	cat >> "${ED}/usr/include/gentoo/maybe-stddefs.h" <<-EOF || die
+	/* __has_include is an extension, but it's fine, because this is only
+	for Clang anyway. */
+	#if defined __has_include && __has_include (<stdc-predef.h>)
+	# include <stdc-predef.h>
+	#endif
+	EOF
+
 	local fortify_level=$(usex hardened 3 2)
 	# We have to do this because glibc's headers warn if F_S is set
 	# without optimization and that would at the very least be very noisy
diff --git a/sys-devel/clang-common/clang-common-17.0.0_pre20230502.ebuild b/sys-devel/clang-common/clang-common-17.0.0_pre20230502.ebuild
index 5b4a6647f3ca..ffae670e7202 100644
--- a/sys-devel/clang-common/clang-common-17.0.0_pre20230502.ebuild
+++ b/sys-devel/clang-common/clang-common-17.0.0_pre20230502.ebuild
@@ -87,6 +87,8 @@ src_install() {
 		@gentoo-runtimes.cfg
 		@gentoo-gcc-install.cfg
 		@gentoo-hardened.cfg
+		# bug #870001
+		-include "${EPREFIX}/usr/include/gentoo/maybe-stddefs.h"
 	EOF
 
 	# Baseline hardening (bug #851111)
@@ -101,6 +103,14 @@ src_install() {
 
 	dodir /usr/include/gentoo
 
+	cat >> "${ED}/usr/include/gentoo/maybe-stddefs.h" <<-EOF || die
+	/* __has_include is an extension, but it's fine, because this is only
+	for Clang anyway. */
+	#if defined __has_include && __has_include (<stdc-predef.h>)
+	# include <stdc-predef.h>
+	#endif
+	EOF
+
 	local fortify_level=$(usex hardened 3 2)
 	# We have to do this because glibc's headers warn if F_S is set
 	# without optimization and that would at the very least be very noisy
diff --git a/sys-devel/clang-common/clang-common-17.0.0_pre20230512.ebuild b/sys-devel/clang-common/clang-common-17.0.0_pre20230512.ebuild
index 5b4a6647f3ca..ffae670e7202 100644
--- a/sys-devel/clang-common/clang-common-17.0.0_pre20230512.ebuild
+++ b/sys-devel/clang-common/clang-common-17.0.0_pre20230512.ebuild
@@ -87,6 +87,8 @@ src_install() {
 		@gentoo-runtimes.cfg
 		@gentoo-gcc-install.cfg
 		@gentoo-hardened.cfg
+		# bug #870001
+		-include "${EPREFIX}/usr/include/gentoo/maybe-stddefs.h"
 	EOF
 
 	# Baseline hardening (bug #851111)
@@ -101,6 +103,14 @@ src_install() {
 
 	dodir /usr/include/gentoo
 
+	cat >> "${ED}/usr/include/gentoo/maybe-stddefs.h" <<-EOF || die
+	/* __has_include is an extension, but it's fine, because this is only
+	for Clang anyway. */
+	#if defined __has_include && __has_include (<stdc-predef.h>)
+	# include <stdc-predef.h>
+	#endif
+	EOF
+
 	local fortify_level=$(usex hardened 3 2)
 	# We have to do this because glibc's headers warn if F_S is set
 	# without optimization and that would at the very least be very noisy