This release is the result of the community’s work over the past six months, including: retpoline Spectre variant 2 mitigation, significantly improved CodeView debug info for Windows, GlobalISel by default for AArch64 at -O0, improved scheduling on several x86 micro-architectures, Clang defaults to -std=gnu++14 instead of -std=gnu++98, support for some upcoming C++2a features, improved optimizations, new compiler warnings, many bug fixes, and more.

https://llvm.org/releases/download.html#6.0.0
https://llvm.org/releases/6.0.0/docs/ReleaseNotes.html
https://llvm.org/releases/6.0.0/tools/clang/docs/ReleaseNotes.html
https://llvm.org/releases/6.0.0/tools/clang/tools/extra/docs/ReleaseNotes.html
https://llvm.org/releases/6.0.0/tools/lld/docs/ReleaseNotes.html
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