Enum AssignOp 

pub enum AssignOp {
    Binary(BinOp),
    Logical(LogicalOp),
}

The operator carried by a COMPOUND assignment (a += b, a ??= b).

It rides on the Expr::Assign node rather than being desugared away at parse time. The parser used to rewrite a op= b into a = a op b, which duplicates the target expression — so every side effect in the target ran TWICE. o[k()] += 1 called k once in node and twice here, and the same held for the logical forms even when they short-circuited and never wrote. Duplication cannot be undone later by inspecting the tree, because o[k()] = o[k()] + 1 is a DIFFERENT program that legitimately calls k twice and is structurally identical after the rewrite.

Variants

Binary(BinOp)

+= -= *= /= %= **= &= |= ^= <<= >>= >>>= — always reads, computes, writes.

Logical(LogicalOp)

&&= ||= ??= — reads, and writes only if the read did not short-circuit.

Trait Implementations

impl Clone for AssignOp

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for AssignOp

impl Debug for AssignOp

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for AssignOp

impl PartialEq for AssignOp

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for AssignOp