Update compiler for Node.js 16

[richardlau]

Node.js 16 requires gcc/g++ 8.3 or later.

V8 9.2 included in Node.js 16.6.0 fails to compile with gcc/g++ 8.2.1:
https://unofficial-builds.nodejs.org/logs/202107292303-v16.6.0/x64-usdt.log

../deps/v8/src/builtins/builtins-call-gen.cc: In instantiation of 'void v8::internal::CallOrConstructBuiltinsAssembler::CallReceiver(v8::internal::Builtins::Name, v8::internal::TNode<v8::internal::Int32T>, v8::internal::TNode<v8::internal::UintPtrT>, v8::base::Optional<v8::internal::TNode<v8::internal::Object> >) [with Descriptor = v8::internal::CallTrampoline_BaselineDescriptor]':
../deps/v8/src/builtins/builtins-call-gen.cc:81:42:   required from here
../deps/v8/src/builtins/builtins-call-gen.cc:491:14: error: passing 'const v8::base::Optional<v8::internal::TNode<v8::internal::Object> >' as 'this' argument discards qualifiers [-fpermissive]
       return *maybe_receiver;
              ^~~~~~~~~~~~~~~
In file included from ../deps/v8/src/compiler/code-assembler.h:17,
                 from ../deps/v8/src/codegen/code-stub-assembler.h:15,
                 from ../deps/v8/src/builtins/builtins-call-gen.h:8,
                 from ../deps/v8/src/builtins/builtins-call-gen.cc:5:
../deps/v8/src/base/optional.h:575:16: note:   in call to 'constexpr T& v8::base::Optional<T>::operator*() & [with T = v8::internal::TNode<v8::internal::Object>]'
   constexpr T& operator*() & {
                ^~~~~~~~
../deps/v8/src/builtins/builtins-call-gen.cc: In instantiation of 'void v8::internal::CallOrConstructBuiltinsAssembler::CallReceiver(v8::internal::Builtins::Name, v8::internal::TNode<v8::internal::Int32T>, v8::internal::TNode<v8::internal::UintPtrT>, v8::base::Optional<v8::internal::TNode<v8::internal::Object> >) [with Descriptor = v8::internal::CallTrampoline_Baseline_CompactDescriptor]':
../deps/v8/src/builtins/builtins-call-gen.cc:479:3:   required from 'void v8::internal::CallOrConstructBuiltinsAssembler::CallReceiver(v8::internal::Builtins::Name, v8::base::Optional<v8::internal::TNode<v8::internal::Object> >) [with Descriptor = v8::internal::CallTrampoline_Baseline_CompactDescriptor]'
../deps/v8/src/builtins/builtins-call-gen.cc:72:79:   required from here
../deps/v8/src/builtins/builtins-call-gen.cc:491:14: error: passing 'const v8::base::Optional<v8::internal::TNode<v8::internal::Object> >' as 'this' argument discards qualifiers [-fpermissive]
       return *maybe_receiver;
              ^~~~~~~~~~~~~~~
In file included from ../deps/v8/src/compiler/code-assembler.h:17,
                 from ../deps/v8/src/codegen/code-stub-assembler.h:15,
                 from ../deps/v8/src/builtins/builtins-call-gen.h:8,
                 from ../deps/v8/src/builtins/builtins-call-gen.cc:5:
../deps/v8/src/base/optional.h:575:16: note:   in call to 'constexpr T& v8::base::Optional<T>::operator*() & [with T = v8::internal::TNode<v8::internal::Object>]'
   constexpr T& operator*() & {
                ^~~~~~~~
In file included from /opt/rh/devtoolset-8/root/usr/include/c++/8/functional:59,
                 from ../deps/v8/src/codegen/code-stub-assembler.h:8,
                 from ../deps/v8/src/builtins/builtins-call-gen.h:8,
                 from ../deps/v8/src/builtins/builtins-call-gen.cc:5:
/opt/rh/devtoolset-8/root/usr/include/c++/8/bits/std_function.h:666:7: error: 'std::function<_Res(_ArgTypes ...)>::function(_Functor) [with _Functor = v8::internal::CallOrConstructBuiltinsAssembler::CallReceiver(v8::internal::Builtins::Name, v8::internal::TNode<v8::internal::Int32T>, v8::internal::TNode<v8::internal::UintPtrT>, v8::base::Optional<v8::internal::TNode<v8::internal::Object> >) [with Descriptor = v8::internal::CallTrampoline_BaselineDescriptor]::<lambda()>; <template-parameter-2-2> = void; <template-parameter-2-3> = void; _Res = v8::internal::TNode<v8::internal::Object>; _ArgTypes = {}]', declared using local type 'v8::internal::CallOrConstructBuiltinsAssembler::CallReceiver(v8::internal::Builtins::Name, v8::internal::TNode<v8::internal::Int32T>, v8::internal::TNode<v8::internal::UintPtrT>, v8::base::Optional<v8::internal::TNode<v8::internal::Object> >) [with Descriptor = v8::internal::CallTrampoline_BaselineDescriptor]::<lambda()>', is used but never defined [-fpermissive]
       function<_Res(_ArgTypes...)>::
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/rh/devtoolset-8/root/usr/include/c++/8/bits/std_function.h:666:7: error: 'std::function<_Res(_ArgTypes ...)>::function(_Functor) [with _Functor = v8::internal::CallOrConstructBuiltinsAssembler::CallReceiver(v8::internal::Builtins::Name, v8::internal::TNode<v8::internal::Int32T>, v8::internal::TNode<v8::internal::UintPtrT>, v8::base::Optional<v8::internal::TNode<v8::internal::Object> >) [with Descriptor = v8::internal::CallTrampoline_Baseline_CompactDescriptor]::<lambda()>; <template-parameter-2-2> = void; <template-parameter-2-3> = void; _Res = v8::internal::TNode<v8::internal::Object>; _ArgTypes = {}]', declared using local type 'v8::internal::CallOrConstructBuiltinsAssembler::CallReceiver(v8::internal::Builtins::Name, v8::internal::TNode<v8::internal::Int32T>, v8::internal::TNode<v8::internal::UintPtrT>, v8::base::Optional<v8::internal::TNode<v8::internal::Object> >) [with Descriptor = v8::internal::CallTrampoline_Baseline_CompactDescriptor]::<lambda()>', is used but never defined [-fpermissive]
make[2]: *** [tools/v8_gypfiles/v8_initializers.target.mk:388: /home/node/node-v16.6.0/out/Release/obj.target/v8_initializers/deps/v8/src/builtins/builtins-call-gen.o] Error 1

The baseline compiler requirement for Node.js 16 is gcc/g++ 8.3: https://github.com/nodejs/node/blob/v16.0.0/BUILDING.md#supported-toolchains

This PR updates the compiler used for Node.js 16 and later by enabling devtoolset-9.

The Cloud Linux repo's devtoolset-8 package is gcc/g++ 8.2.1:
https://repo.cloudlinux.com/cloudlinux/7/sclo/devtoolset-8/x86_64/

FWIW Software Collections does have a devtoolset-8 that provides gcc/g++ 8.3.1 but only for x64:
http://mirror.centos.org/centos/7/sclo/x86_64/rh/Packages/d/

Pointer compression builds were separately broken in 16.4.0 nodejs/TSC#790 (comment) and may need nodejs/node#39664 (not yet in a release).

[rvagg]

seems fine to me
I take it that this is only impacting the images that are centos/rhel based so those are the ones getting the udpate?

[richardlau]

I take it that this is only impacting the images that are centos/rhel based so those are the ones getting the udpate?

Correct.