Driver: Don't mix system tools with devtoolset tools on RHEL

[tstellar]

Summary

On RHEL, devtoolset provides a more up-to-date toolchain than the base
install, and we want to make sure all the tools use are from the same
toolchain.

[tstellar]

Ping.u1

[tstellar]

Ping.

[tstellar]

Ping.

[tstellar]

Ping.

[bruno]

Is there a way to test this?

lib/Driver/ToolChains/Linux.cpp

237

You can remove the curly braces here.

[tstellar]

Replaced the if (Distro.isRedhat()) check with a string compare on the
GCC installation lib. This narrows the scope of the fix and also makes
it possible to write a test case. The code that detects distros ignores
sysroot and looks in /etc of the test system, which makes it impossible to
write a portable lit test to verify distro specific behavior.

[bruno]

LGTM, thanks!

lib/Driver/ToolChains/Linux.cpp

Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
 
   if (Distro.IsAlpineLinux()) {
     ExtraOpts.push_back("-z");
     ExtraOpts.push_back("now");
   }
 
   if (Distro.IsOpenSUSE() || Distro.IsUbuntu() || Distro.IsAlpineLinux()) {
     ExtraOpts.push_back("-z");
     ExtraOpts.push_back("relro");
   }
 
+  if (GCCInstallation.getParentLibPath().find("opt/rh/devtoolset") !=
+      StringRef::npos)
+    // With devtoolset on RHEL, we want to add a bin directory that is relative
+    // to the detected gcc install, because if we are using devtoolset gcc then
+    // we want to use other tools from devtoolset (e.g. ld) instead of the
+    // standard system tools.
+    PPaths.push_back(Twine(GCCInstallation.getParentLibPath() +
+                     "/../bin").str());
+
   if (Arch == llvm::Triple::arm || Arch == llvm::Triple::thumb)
     ExtraOpts.push_back("-X");
 
   const bool IsAndroid = Triple.isAndroid();
   const bool IsMips = tools::isMipsArch(Arch);
   const bool IsHexagon = Arch == llvm::Triple::hexagon;
   const bool IsRISCV =
       Arch == llvm::Triple::riscv32 || Arch == llvm::Triple::riscv64;

test/Driver/linux-ld.c

 // CHECK-LD-GENTOO-X32: "-dynamic-linker"
 // CHECK-LD-GENTOO-X32: "{{.*}}/usr/lib/gcc/x86_64-pc-linux-gnu/4.9.3/x32{{/|\\\\}}crtbegin.o"
 // CHECK-LD-GENTOO-X32: "-L[[SYSROOT]]/usr/lib/gcc/x86_64-pc-linux-gnu/4.9.3/x32"
 // CHECK-LD-GENTOO-X32: "-L[[SYSROOT]]/usr/lib/gcc/x86_64-pc-linux-gnu/4.9.3/../../../../x86_64-pc-linux-gnu/lib"
 // CHECK-LD-GENTOO-X32: "-L[[SYSROOT]]/usr/lib/gcc/x86_64-pc-linux-gnu/4.9.3/../../.."
 // CHECK-LD-GENTOO-X32: "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed"
 // CHECK-LD-GENTOO-X32: "-lc"
 // CHECK-LD-GENTOO-X32: "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed"
+
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     --gcc-toolchain="%S/Inputs/rhel_7_tree/opt/rh/devtoolset-7/root/usr" \
+// RUN:     --sysroot=%S/Inputs/rhel_7_tree \
+// RUN:   | FileCheck --check-prefix=CHECK-LD-RHEL7-DTS %s
+// CHECK-LD-RHLE7-DTS: Selected GCC installation: [[GCC_INSTALL:/home/tstellar/llvm-project/clang/test/Driver/Inputs/rhel_7_tree/opt/rh/devtoolset-7/root/usr/lib/gcc/x86_64-redhat-linux/7]]
+// CHECK-LD-RHEL7-DTS-NOT: /usr/bin/ld
+// CHECK-LD-RHLE7-DTS: [[GCC_INSTALL]/../../../bin/ld