Enabling the detection of devtoolset-11 toolchain.

[kamaub]

Summary

This patch allows systems to build the llvm-project with the devtoolset-11
toolchain.

[phosek]

LGTM

[tstellar]

clang/lib/Driver/ToolChains/Gnu.cpp

2155

Can you also add gcc-toolset-11 to the search paths?

[MaskRay]

clang/lib/Driver/ToolChains/Gnu.cpp

2157

The detection is wasted every Linux user (even if they don't use RedHat/Fedora). Some may need to be refactored to detect /opt/rh first. Some ancient devtoolset-* may be deleted now.

[tstellar]

clang/lib/Driver/ToolChains/Gnu.cpp

2157

@kamaub Are you planning to address these comments in a follow up change?

[tstellar]

I'm curious what is your system configuration where this patch actually allows for detection of devtoolset? I noticed that if clang and gcc are both installed to /usr/, then driver will pick the gcc in /usr/ over the one in /opt/rh/.../

[kamaub]

In D125499#3541689, @tstellar wrote:

I'm curious what is your system configuration where this patch actually allows for detection of devtoolset? I noticed that if clang and gcc are both installed to /usr/, then driver will pick the gcc in /usr/ over the one in /opt/rh/.../

The machine I needed the devtoolset-11 path for is not the same as the current bot failure trying to be addressed in https://reviews.llvm.org/D127310 but all there isn'y anything special to the configuration, I have /opt/rh/devtoolset-11/root/usr installed as normal from the yum repositories and I had a check-all build failure without this patch

~/Github/build $ ninja check-all
[25/1032] Generating ScudoUnitTestsObjects.wrappers_cpp_test.cpp.powerpc64.o
FAILED: projects/compiler-rt/lib/scudo/standalone/tests/ScudoUnitTestsObjects.wrappers_cpp_test.cpp.powerpc64.o
cd /home/kamaub/Github/build/projects/compiler-rt/lib/scudo/standalone/tests && /home/kamaub/Github/build/./bin/clang -g -Wno-suggest-override -DGTEST_NO_LLVM_SUPPORT=1 -DGTEST_HAS_RTTI=0 -I/home/kamaub/Github/llvm-project/llvm/utils/unittest/googletest/include -I/home/kamaub/Github/llvm-project/llvm/utils/unittest/googletest -I/home/kamaub/Github/llvm-project/compiler-rt/include -I/home/kamaub/Github/llvm-project/compiler-rt/lib -I/home/kamaub/Github/llvm-project/compiler-rt/lib/scudo/standalone -I/home/kamaub/Github/llvm-project/compiler-rt/lib/scudo/standalone/include -DGTEST_HAS_RTTI=0 -g -Wno-mismatched-new-delete -m64 -c -o ScudoUnitTestsObjects.wrappers_cpp_test.cpp.powerpc64.o /home/kamaub/Github/llvm-project/compiler-rt/lib/scudo/standalone/tests/wrappers_cpp_test.cpp
/home/kamaub/Github/llvm-project/compiler-rt/lib/scudo/standalone/tests/wrappers_cpp_test.cpp:118:19: error: no member named 'make_unique' in namespace 'std'
    NoTags = std::make_unique<scudo::ScopedDisableMemoryTagChecks>();
             ~~~~~^
/home/kamaub/Github/llvm-project/compiler-rt/lib/scudo/standalone/tests/wrappers_cpp_test.cpp:118:66: error: expected '(' for function-style cast or type construction
    NoTags = std::make_unique<scudo::ScopedDisableMemoryTagChecks>();
                              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
/home/kamaub/Github/llvm-project/compiler-rt/lib/scudo/standalone/tests/wrappers_cpp_test.cpp:118:68: error: expected expression
    NoTags = std::make_unique<scudo::ScopedDisableMemoryTagChecks>();
                                                                   ^
3 errors generated.

clang/lib/Driver/ToolChains/Gnu.cpp

2157

@tstellar Sorry I missed this, thank you for pointing it out, I should have addressed this in a follow-up chain but I email notifications are not working as only saw these comment while taking a look at https://reviews.llvm.org/D127310

clang/lib/Driver/ToolChains/Gnu.cpp

for (llvm::vfs::directory_iterator LI = D.getVFS().dir_begin(PrefixDir, EC),
       Prefixes.push_back(CandidatePrefix);
     }
     return;
   }
 
   // Non-Solaris is much simpler - most systems just go with "/usr".
   if (SysRoot.empty() && TargetTriple.getOS() == llvm::Triple::Linux) {
     // Yet, still look for RHEL/CentOS devtoolsets and gcc-toolsets.
+    Prefixes.push_back("/opt/rh/gcc-toolset-11/root/usr");
     Prefixes.push_back("/opt/rh/gcc-toolset-10/root/usr");
+    Prefixes.push_back("/opt/rh/devtoolset-11/root/usr");
     Prefixes.push_back("/opt/rh/devtoolset-10/root/usr");
     Prefixes.push_back("/opt/rh/devtoolset-9/root/usr");
     Prefixes.push_back("/opt/rh/devtoolset-8/root/usr");
     Prefixes.push_back("/opt/rh/devtoolset-7/root/usr");
     Prefixes.push_back("/opt/rh/devtoolset-6/root/usr");
     Prefixes.push_back("/opt/rh/devtoolset-4/root/usr");
     Prefixes.push_back("/opt/rh/devtoolset-3/root/usr");
     Prefixes.push_back("/opt/rh/devtoolset-2/root/usr");
   }
   Prefixes.push_back(SysRoot.str() + "/usr");