Go release 1.20

Go 1.20 arrives six months after Go 1.19 with most changes in the toolchain, runtime, and libraries. It maintains the Go 1 compatibility promise.

• Conversions from slice to array are now allowed.
• Three new functions in the unsafe package: SliceData, String, and StringData.
• Struct and array comparisons are now well-defined, stopping at the first mismatch.
• Comparable types can satisfy comparable constraints even if type arguments are not strictly comparable.

• Last release for Windows 7, 8, Server 2008 and Server 2012. Future versions will require Windows 10 or Server 2016.
• Last release for macOS 10.13 High Sierra or 10.14 Mojave. Future versions will require macOS 10.15 Catalina or later.
• Experimental support for FreeBSD on RISC-V.

• Standard library package archives are no longer stored in $GOROOT/pkg.
• Improved robustness for go test -json implementation.
• Support for architecture feature build tags.
• go commands accept -C <dir> to change directory before performing the command.
• Profile-guided optimization (PGO) and code coverage instrumentation with the -cover flag.

• Garbage collector's internal data structures reorganized for better efficiency.
• Less erratic behavior in garbage collector with respect to goroutine assists.
• New runtime/coverage package for writing coverage profile data at runtime.

• Preview support for profile-guided optimization (PGO).
• Compiler front-end upgraded for better handling of internal data and generics.
• Compiler now rejects anonymous interface cycles by default.
• Improved build speeds by up to 10%, reverting to Go 1.17 performance levels.

• On Linux, dynamic interpreter selected at link time for glibc or musl.
• On Windows, support for modern LLVM-based C toolchains.
• Compiler-generated symbols now use go: and type: prefixes to avoid user package confusion.

• Go 1.20 requires Go 1.17.13 for bootstrapping.
• Future versions plan to move the bootstrap toolchain forward approximately once a year.

• New crypto/ecdh package for Elliptic Curve Diffie-Hellman key exchanges.
• Support for wrapping multiple errors in errors package.
• New ResponseController type in net/http for extended per-request functionality.
• New ReverseProxy Rewrite hook in net/http/httputil for more secure and flexible proxy requests.