[gentoo-dev] [PATCH 1/2] toolchain-funcs.eclass: Add tc-get-compiler-type()

[Michał Górny]

Add a tc-get-compiler-type() function that can be used to identify
the compiler being used, using the preprocessor defines. Alike
gcc-*version() routines, it uses CPP (which in turn uses CC).

The major usage would be applying compiler-specific quirks and limiting
gcc version checks to compilers that actually are gcc, since e.g. clang
reports gcc version 4.2 -- which would incorrectly cause numerous gcc
version checks in ebuilds to fail.
---
 eclass/tests/toolchain-funcs.sh | 15 +++++++++++++++
 eclass/toolchain-funcs.eclass   | 19 +++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/eclass/tests/toolchain-funcs.sh b/eclass/tests/toolchain-funcs.sh
index 41c1ae5..0b9b7d7 100755
--- a/eclass/tests/toolchain-funcs.sh
+++ b/eclass/tests/toolchain-funcs.sh
@@ -111,5 +111,20 @@ tc-ld-disable-gold
 )
 tend $?
 
+tbegin "tc-get-compiler-type (gcc)"
+(
+export CC=gcc
+[[ $(tc-get-compiler-type) == gcc ]]
+)
+tend $?
+
+if type -P clang &>/dev/null; then
+	tbegin "tc-get-compiler-type (clang)"
+	(
+	export CC=clang
+	[[ $(tc-get-compiler-type) == clang ]]
+	)
+	tend $?
+fi
 
 texit
diff --git a/eclass/toolchain-funcs.eclass b/eclass/toolchain-funcs.eclass
index 3398775..4a45f78 100644
--- a/eclass/toolchain-funcs.eclass
+++ b/eclass/toolchain-funcs.eclass
@@ -585,6 +585,25 @@ tc-endian() {
 	esac
 }
 
+# @FUNCTION: tc-get-compiler-type
+# @RETURN: keyword identifying the compiler: gcc, clang, unknown
+tc-get-compiler-type() {
+	local code='
+#if defined(__clang__)
+	HAVE_CLANG
+#elif defined(__GNUC__)
+	HAVE_GCC
+#endif
+'
+	local res=$($(tc-getCPP "$@") -E -P - <<<"${code}")
+
+	case ${res} in
+		*HAVE_CLANG*)	echo clang;;
+		*HAVE_GCC*)		echo gcc;;
+		*)				echo unknown;;
+	esac
+}
+
 # Internal func.  The first argument is the version info to expand.
 # Query the preprocessor to improve compatibility across different
 # compilers rather than maintaining a --version flag matrix. #335943
-- 
2.9.0