[PATCH 2/4] common: implement CC_IS_GCC and CC_IS_CLANG symbols

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

As preparation for support LLVM+clang, we need barebox to be able to
detect what compiler is being used and its version.

Import the necessary infrastructure from Linux.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 common/Kconfig          | 16 +++++++++++++
 scripts/Kconfig.include |  6 +++++
 scripts/cc-version.sh   | 52 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 74 insertions(+)
 create mode 100755 scripts/cc-version.sh

diff --git a/common/Kconfig b/common/Kconfig
index 859356038386..498d219b4de3 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -2,6 +2,22 @@
 
 source "common/boards/Kconfig"
 
+config CC_IS_GCC
+	def_bool $(success,test "$(cc-name)" = GCC)
+
+config GCC_VERSION
+	int
+	default $(cc-version) if CC_IS_GCC
+	default 0
+
+config CC_IS_CLANG
+	def_bool $(success,test "$(cc-name)" = Clang)
+
+config CLANG_VERSION
+	int
+	default $(cc-version) if CC_IS_CLANG
+	default 0
+
 config GREGORIAN_CALENDER
 	bool
 
diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
index a5fe72c504ff..55ec8737d0db 100644
--- a/scripts/Kconfig.include
+++ b/scripts/Kconfig.include
@@ -23,6 +23,12 @@ success = $(if-success,$(1),y,n)
 # Return n if <command> exits with 0, y otherwise
 failure = $(if-success,$(1),n,y)
 
+# Get the C compiler name, version, and error out if it is not supported.
+cc-info := $(shell,$(srctree)/scripts/cc-version.sh $(CC))
+$(error-if,$(success,test -z "$(cc-info)"),Sorry$(comma) this C compiler is not supported.)
+cc-name := $(shell,set -- $(cc-info) && echo $1)
+cc-version := $(shell,set -- $(cc-info) && echo $2)
+
 # $(cc-option,<flag>)
 # Return y if the compiler supports <flag>, n otherwise
 cc-option = $(success,mkdir .tmp_$$$$; trap "rm -rf .tmp_$$$$" EXIT; $(CC) -Werror $(CLANG_FLAGS) $(1) -c -x c /dev/null -o .tmp_$$$$/tmp.o)
diff --git a/scripts/cc-version.sh b/scripts/cc-version.sh
new file mode 100755
index 000000000000..65d8a2805d2e
--- /dev/null
+++ b/scripts/cc-version.sh
@@ -0,0 +1,52 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# Print the C compiler name and its version in a 5 or 6-digit form.
+# Also, perform the minimum version check.
+
+set -e
+
+# Print the C compiler name and some version components.
+get_c_compiler_info()
+{
+	cat <<- EOF | "$@" -E -P -x c - 2>/dev/null
+	#if defined(__clang__)
+	Clang	__clang_major__  __clang_minor__  __clang_patchlevel__
+	#elif defined(__GNUC__)
+	GCC	__GNUC__  __GNUC_MINOR__  __GNUC_PATCHLEVEL__
+	#else
+	unknown
+	#endif
+	EOF
+}
+
+# Convert the version string x.y.z to a canonical 5 or 6-digit form.
+get_canonical_version()
+{
+	IFS=.
+	set -- $1
+	echo $((10000 * $1 + 100 * $2 + $3))
+}
+
+# $@ instead of $1 because multiple words might be given, e.g. CC="ccache gcc".
+orig_args="$@"
+set -- $(get_c_compiler_info "$@")
+
+name=$1
+
+case "$name" in
+GCC)
+	version=$2.$3.$4
+	;;
+Clang)
+	version=$2.$3.$4
+	;;
+*)
+	echo "$orig_args: unknown C compiler" >&2
+	exit 1
+	;;
+esac
+
+cversion=$(get_canonical_version $version)
+
+echo $name $cversion
-- 
2.39.5