[Driver] Support GCC detection for GCC compiled with --enable-version-specific-runtime-libs

GCC's compiled with --enable-version-specific-runtime-libs change the paths where includes and libs are found.
This patch adds support for these cases

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D118700

clang/lib/Driver/ToolChains/Gnu.cpp

@@ -2803,6 +2803,11 @@ void Generic_GCC::AddMultilibPaths(const Driver &D,
         D, GCCInstallation.getInstallPath() + SelectedMultilib.gccSuffix(),
         Paths);
 
+    // Add lib/gcc/$triple/$libdir
+    // For GCC built with --enable-version-specific-runtime-libs.
+    addPathIfExists(D, GCCInstallation.getInstallPath() + "/../" + OSLibDir,
+                    Paths);
+
     // GCC cross compiling toolchains will install target libraries which ship
     // as part of the toolchain under <prefix>/<triple>/<libdir> rather than as
     // any part of the GCC installation in
@@ -2981,6 +2986,15 @@ bool Generic_GCC::addGCCLibStdCxxIncludePaths(
           TripleStr, Multilib.includeSuffix(), DriverArgs, CC1Args))
     return true;
 
+  // Try /gcc/$triple/$version/include/c++/ (gcc --print-multiarch is not
+  // empty). Like above but for GCC built with
+  // --enable-version-specific-runtime-libs.
+  if (addLibStdCXXIncludePaths(LibDir.str() + "/gcc/" + TripleStr + "/" +
+                                   Version.Text + "/include/c++/",
+                               TripleStr, Multilib.includeSuffix(), DriverArgs,
+                               CC1Args))
+    return true;
+
   // Detect Debian g++-multiarch-incdir.diff.
   if (addLibStdCXXIncludePaths(LibDir.str() + "/../include/c++/" + Version.Text,
                                DebianMultiarch, Multilib.includeSuffix(),

clang/test/Driver/gcc-toolchain-rt-libs-multi.cpp

@@ -0,0 +1,22 @@
+// RUN: %clangxx %s -### -stdlib=libstdc++ --gcc-toolchain=%S/Inputs/gcc_version_parsing_rt_libs_multilib --target=x86_64-redhat-linux 2>&1 | FileCheck %s -check-prefix=X64-STDCPLUS
+// RUN: %clangxx %s -### -stdlib=libc++ --gcc-toolchain=%S/Inputs/gcc_version_parsing_rt_libs_multilib --target=x86_64-redhat-linux 2>&1 | FileCheck %s -check-prefix=X64-LIBCPLUS
+// RUN: %clangxx %s -m32 -### -stdlib=libstdc++ --gcc-toolchain=%S/Inputs/gcc_version_parsing_rt_libs_multilib --target=x86_64-redhat-linux 2>&1 | FileCheck %s -check-prefix=X32-STDCPLUS
+// RUN: %clangxx %s -m32 -### -stdlib=libc++ --gcc-toolchain=%S/Inputs/gcc_version_parsing_rt_libs_multilib --target=x86_64-redhat-linux 2>&1 | FileCheck %s -check-prefix=X32-LIBCPLUS
+
+int main() {}
+
+// X64-STDCPLUS: "-internal-isystem" "{{[^ ]*}}gcc_version_parsing_rt_libs_multilib/lib/gcc/x86_64-redhat-linux/10.2.0/../../../gcc/x86_64-redhat-linux/10.2.0/include/c++/"
+// X64-STDCPLUS: "-L{{[^ ]*}}gcc_version_parsing_rt_libs_multilib/lib/gcc/x86_64-redhat-linux/10.2.0"
+// X64-STDCPLUS: "-L{{[^ ]*}}gcc_version_parsing_rt_libs_multilib/lib/gcc/x86_64-redhat-linux/10.2.0/../lib64"
+
+// X64-LIBCPLUS-NOT: "-internal-isystem" "{{[^ ]*}}gcc_version_parsing_rt_libs_multilib/lib/gcc/x86_64-redhat-linux/10.2.0/../../../gcc/x86_64-redhat-linux/10.2.0/include/c++/"
+// X64-LIBCPLUS: "-L{{[^ ]*}}gcc_version_parsing_rt_libs_multilib/lib/gcc/x86_64-redhat-linux/10.2.0"
+// X64-LIBCPLUS: "-L{{[^ ]*}}gcc_version_parsing_rt_libs_multilib/lib/gcc/x86_64-redhat-linux/10.2.0/../lib64"
+
+// X32-STDCPLUS: "-internal-isystem" "{{[^ ]*}}gcc_version_parsing_rt_libs_multilib/lib/gcc/x86_64-redhat-linux/10.2.0/../../../gcc/x86_64-redhat-linux/10.2.0/include/c++/"
+// X32-STDCPLUS: "-L{{[^ ]*}}gcc_version_parsing_rt_libs_multilib/lib/gcc/x86_64-redhat-linux/10.2.0/32"
+// X32-STDCPLUS: "-L{{[^ ]*}}gcc_version_parsing_rt_libs_multilib/lib/gcc/x86_64-redhat-linux/10.2.0/../lib32"
+
+// X32-LIBCPLUS-NOT: "-internal-isystem" "{{[^ ]*}}gcc_version_parsing_rt_libs_multilib/lib/gcc/x86_64-redhat-linux/10.2.0/../../../gcc/x86_64-redhat-linux/10.2.0/include/c++/"
+// X32-LIBCPLUS: "-L{{[^ ]*}}gcc_version_parsing_rt_libs_multilib/lib/gcc/x86_64-redhat-linux/10.2.0/32"
+// X32-LIBCPLUS: "-L{{[^ ]*}}gcc_version_parsing_rt_libs_multilib/lib/gcc/x86_64-redhat-linux/10.2.0/../lib32"

clang/test/Driver/gcc-toolchain-rt-libs.cpp

@@ -0,0 +1,12 @@
+// RUN: %clangxx %s -### -stdlib=libstdc++ --gcc-toolchain=%S/Inputs/gcc_version_parsing_rt_libs --target=x86_64-redhat-linux 2>&1 | FileCheck %s -check-prefix=STDCPLUS
+// RUN: %clangxx %s -### -stdlib=libc++ --gcc-toolchain=%S/Inputs/gcc_version_parsing_rt_libs --target=x86_64-redhat-linux 2>&1 | FileCheck %s -check-prefix=LIBCPLUS
+
+int main() {}
+
+// STDCPLUS: "-internal-isystem" "{{[^ ]*}}gcc_version_parsing_rt_libs/lib/gcc/x86_64-redhat-linux/10.2.0/../../../gcc/x86_64-redhat-linux/10.2.0/include/c++/"
+// STDCPLUS: "-L{{.*}}gcc_version_parsing_rt_libs/lib/gcc/x86_64-redhat-linux/10.2.0"
+// STDCPLUS: "-L{{.*}}gcc_version_parsing_rt_libs/lib/gcc/x86_64-redhat-linux/10.2.0/../lib64"
+
+// LIBCPLUS-NOT: "-internal-isystem" "{{[^ ]*}}gcc_version_parsing_rt_libs/lib/gcc/x86_64-redhat-linux/10.2.0/../../../gcc/x86_64-redhat-linux/10.2.0/include/c++/"
+// LIBCPLUS: "-L{{.*}}gcc_version_parsing_rt_libs/lib/gcc/x86_64-redhat-linux/10.2.0"
+// LIBCPLUS: "-L{{.*}}gcc_version_parsing_rt_libs/lib/gcc/x86_64-redhat-linux/10.2.0/../lib64"