Go Right Shift Assignment

x >>= y

x = x >> y

​

Technical Mechanics

• Both the left and right operands must resolve to integer types.
• The right operand (shift count) dictates the number of bits to shift. If the shift count evaluates to a negative value at runtime, Go will trigger a panic.

1. Logical Right Shift (Unsigned Integers): If the left operand is an unsigned integer type (e.g., uint8, uint64), >>= performs a logical right shift. The bits are shifted to the right, and the vacated Most Significant Bits (MSBs) on the left are filled with zeros.

2. **Arithmetic Right Shift (Signed Integers):**
   If the left operand is a signed integer type (e.g., `int8`, `int64`), `>>=` performs an arithmetic right shift. The bits are shifted to the right, but the vacated MSBs are filled with copies of the original sign bit (0 for positive numbers, 1 for negative numbers). This preserves the sign of the two's complement integer.
   ```go
var y int8 = -20 // Binary: 1110 1100 (Two's complement)
y >>= 2          // Shift right by 2 positions
// y is now -5   // Binary: 1111 1011 (Sign-bit filled MSBs)

​

Out-of-Bounds Shifts

• For unsigned integers, the result evaluates to 0.
• For signed integers, the result evaluates to 0 if the original value was positive, or -1 (all bits set to 1) if the original value was negative.