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Version: 2.9.x(Latest)

Go 1.17 (2021-08-16)

Go 1.17 was released in August 2021, bringing compiler performance improvements, pruned module graphs, and new build tag syntax.

Major Changes​

Language​

  • Slice Conversion: Support for converting slices to array pointers. If the slice length is less than the array length, the conversion panics at runtime.

    s := []int{1, 2, 3}
    p := (*[3]int)(s)

  • unsafe Package: Added unsafe.Add and unsafe.Slice functions, simplifying pointer arithmetic and slice creation, making code more compliant with unsafe.Pointer safety rules.

Toolchain​

  • Pruned Module Graphs: If a module specifies go 1.17 or higher, the module graph includes only the direct dependencies of other go 1.17 modules, no longer loading the full transitive dependency graph. This significantly improves module loading speed for large projects.

  • //go:build Syntax: Introduced the new build tag syntax //go:build, replacing the old // +build, supporting boolean expressions and being more readable.

    //go:build linux || darwin

  • go get Deprecation: The feature of go get to install executables is deprecated (and will be removed in a future version); use go install cmd@version instead.

Performance​

  • Register-based Calling Convention: On x86-64 (amd64) architecture, Go function calls now use registers to pass arguments and results instead of the stack. This brings about a 5% performance improvement and a 2% reduction in binary size.
  • Bounds Check Elimination: Improved bounds check elimination logic, further enhancing performance.

Standard Library​

  • time: Added Time.UnixMilli and Time.UnixMicro methods; added Time.IsDST method to check if it is currently Daylight Saving Time.
  • testing: Added -shuffle flag to randomly shuffle test execution order; added T.Setenv and B.Setenv methods to set environment variables during tests.
  • sync/atomic: atomic.Value added Swap and CompareAndSwap methods.
  • net/http: Semicolons ; are no longer allowed as separators in URL query parameters.
  • runtime/cgo: Added Handle mechanism for safely passing Go values between C and Go.

References​

For more details, please refer to the official release notes: Go 1.17 Release Notes