toolchain-funcs.eclass: Add tc-get-c-rtlib() to get CC runtime

Add a new tc-get-c-rtlib() that attempts to get the runtime used
by the current C compiler.  Currently it supports compiler-rt
and libgcc.

Signed-off-by: Michał Górny <mgorny@gentoo.org>

2 files changed, 38 insertions, 0 deletions

diff --git a/eclass/tests/toolchain-funcs.sh b/eclass/tests/toolchain-funcs.sh
index 5a35a44ce018..d8a357fb24fe 100755
--- a/eclass/tests/toolchain-funcs.sh
+++ b/eclass/tests/toolchain-funcs.sh
@@ -202,6 +202,10 @@ if type -P gcc &>/dev/null; then
 	tbegin "tc-get-cxx-stdlib (gcc)"
 	[[ $(CXX=g++ tc-get-cxx-stdlib) == libstdc++ ]]
 	tend $?
+
+	tbegin "tc-get-c-rtlib (gcc)"
+	[[ $(CC=gcc tc-get-c-rtlib) == libgcc ]]
+	tend $?
 fi
 
 if type -P clang &>/dev/null; then
@@ -218,6 +222,12 @@ if type -P clang &>/dev/null; then
 	tbegin "tc-get-cxx-stdlib (clang, invalid)"
 	! CXX=clang++ CXXFLAGS="-stdlib=invalid" tc-get-cxx-stdlib
 	tend $?
+
+	for rtlib in compiler-rt libgcc; do
+		tbegin "tc-get-c-rtlib (clang, ${rtlib})"
+		[[ $(CC=clang CFLAGS="--rtlib=${rtlib}" tc-get-c-rtlib) == ${rtlib} ]]
+		tend $?
+	done
 fi
 
 texit
diff --git a/eclass/toolchain-funcs.eclass b/eclass/toolchain-funcs.eclass
index 92494158201e..32e446cb2368 100644
--- a/eclass/toolchain-funcs.eclass
+++ b/eclass/toolchain-funcs.eclass
@@ -1209,4 +1209,32 @@ tc-get-cxx-stdlib() {
 	return 0
 }
 
+# @FUNCTION: tc-get-c-rtlib
+# @DESCRIPTION:
+# Attempt to identify the runtime used by the C/C++ compiler.
+# If the runtime is identifed, the function returns 0 and prints one
+# of the following:
+#
+# - ``compiler-rt`` for ``sys-libs/compiler-rt``
+# - ``libgcc`` for ``sys-devel/gcc``'s libgcc
+#
+# If the runtime is not recognized, the function returns 1.
+tc-get-c-rtlib() {
+	local res=$(
+		$(tc-getCC) ${CFLAGS} ${CPPFLAGS} ${LDFLAGS} \
+			-print-libgcc-file-name 2>/dev/null
+	)
+
+	case ${res} in
+		*libclang_rt*)
+			echo compiler-rt;;
+		*libgcc*)
+			echo libgcc;;
+		*)
+			return 1;;
+	esac
+
+	return 0
+}
+
 fi