Go 1.10 (2018-02-16)

Go 1.10 was released on February 16, 2018. This release focuses on toolchain improvements, specifically introducing build caching and test caching, which significantly improve daily development efficiency.

Major Changes

Toolchain

• Build Cache: The go build command now maintains a cache of recently built packages.
  • Mechanism: The build system now detects if a package is out of date based purely on the content of source files, build flags, and compilation metadata, rather than relying on file modification times.
  • Effect: Incremental build speeds are significantly improved. Caching is utilized even when switching branches or changing build flags.
  • Configuration: The cache is stored in the system temporary directory by default and can be controlled via the GOCACHE environment variable.
• Test Cache: The go test command now caches successful test results.
  • Mechanism: If the test executable, command-line arguments, environment variables, and relevant source files have not changed, go test will directly output the previous successful result (marked as (cached)) instead of re-running the test.
  • Limitation: Only successful test results are cached.
  • Bypass: Use go test -count=1 to force re-running tests.
• Cgo Improvements: Cgo now allows C code to directly access Go strings.
  • _GoString_: The _GoString_ type can be used in C code to receive Go string arguments.
  • Functions: _GoStringLen and _GoStringPtr are provided to get the string length and pointer.
• Default GOROOT: If GOROOT is not set, the go tool now attempts to deduce GOROOT based on the path of its own executable, making it easier to move Go installation directories.
• Test Failfast: go test added the -failfast flag to stop running immediately after the first test failure.

Runtime

• GOMAXPROCS: No longer limited to an upper bound of 1024.
• Unicode: Upgraded to Unicode 10.0.

Standard Library

• strings.Builder: Introduced the strings.Builder type for efficiently building strings. Similar to bytes.Buffer, but the String() method does not perform memory copying when returning the string, resulting in higher performance.

  var b strings.Builder
  b.WriteString("Hello, ")
  b.WriteString("World!")
  s := b.String() // "Hello, World!"

• bytes Package: Slices returned by Fields, Split, etc., now have a capacity equal to their length to prevent append operations from overwriting original array data.

• math/round: Added Round and RoundToEven functions.

• encoding/json: Decoder added the DisallowUnknownFields method to report an error when JSON contains unknown fields.

References

For more details, please refer to the official release notes: Go 1.10 Release Notes