July 01, 2025 #rust #traits #patterns Serhii PotapovJuly 01, 2025
Rust's trait system is famously powerful - and famously strict about avoiding ambiguity.
One such rule is that you can't have multiple blanket implementations of the same trait that could potentially apply to the same type.
What Is a Blanket Implementation?
A blanket implementation is a trait implementation that applies to any type meeting certain constraints, typically via generics.
A classic example from the standard library is how From and Into work together:
impl < T, U > Into < U > for T where U : From < T > , { fn into ( self ) -> U { U :: from ( self ) } }
Thanks to this, when you implement From
The Restriction
However, Rust enforces a key rule: no two blanket implementations may overlap - even in theory. Consider:
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