[Driver] Support obtaining active toolchain from gcc-config on Gentoo

Support using gcc-config to determine the correct GCC toolchain location
on Gentoo. In order to do that, attempt to read gcc-config configuration
form [[sysroot]]/etc/env.d/gcc, if no custom toolchain location is
provided.

Differential Revision: https://reviews.llvm.org/D25661

llvm-svn: 285074

1 files changed, 9 insertions, 0 deletions

diff --git a/clang/test/Driver/linux-header-search.cpp b/clang/test/Driver/linux-header-search.cpp
index 5f6ac504a03..491bb4d0e27 100644
--- a/clang/test/Driver/linux-header-search.cpp
+++ b/clang/test/Driver/linux-header-search.cpp
@@ -301,6 +301,15 @@
 // CHECK-GENTOO-4-9-3: "-internal-externc-isystem" "[[SYSROOT]]/include"
 // CHECK-GENTOO-4-9-3: "-internal-externc-isystem" "[[SYSROOT]]/usr/include"
 //
+// Test support for Gentoo's gcc-config -- clang should prefer the older
+// (4.9.3) version over the newer (5.4.0) due to preference specified
+// in /etc/env.d/gcc/x86_64-pc-linux-gnu.
+// RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1 \
+// RUN:     -target x86_64-unknown-linux-gnu -stdlib=libstdc++ \
+// RUN:     --sysroot=%S/Inputs/gentoo_linux_gcc_multi_version_tree \
+// RUN:     --gcc-toolchain="" \
+// RUN:   | FileCheck --check-prefix=CHECK-GENTOO-4-9-3 %s
+//
 // Check header search on Debian 6 / MIPS64
 // RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1 \
 // RUN:     -target mips64-unknown-linux-gnuabi64 -stdlib=libstdc++ \