Version: 2.9.x(Latest)

Go 1.2 (2013-12-01)

Major Changes

Three-Index Slices: Supports s[i:j:k] syntax to specify the capacity of the new slice, preventing the new slice from accessing parts of the original array beyond the specified capacity.
```
// slice length is 2 (4-2), capacity is 5 (7-2)
slice = array[2:4:7]
```
Nil Pointer Safety: The language specification explicitly guarantees that dereferencing a nil pointer (accessing fields, array indices, etc.) will trigger a panic.

Scheduler Preemption: The scheduler can now preempt goroutines during function calls, preventing infinite loops from blocking the entire program, implementing cooperative preemption.
Test Coverage: go test added the -cover flag to calculate code coverage, which can generate detailed HTML reports when used with go tool cover.
Thread Limit: The runtime now limits the maximum number of operating system threads to 10,000 by default, which can be modified via debug.SetMaxThreads.
Stack Size Adjustment: The initial stack size of a goroutine increased from 4KB to 8KB, reducing the performance overhead of stack splitting.

encoding: Added the encoding package, defining common interfaces like BinaryMarshaler and TextMarshaler.
fmt: Printf family functions now support referencing arguments by index.
```
fmt.Printf("%[2]d %[1]d\n", 11, 22) // Output "22 11"
```
text/template: Added comparison functions like eq, ne, lt, le, gt, ge.

For more details, please refer to the official release notes: Go 1.2 Release Notes