L1BlockNumber

Table of Contents

• Overview
• Definitions
• Assumptions
• Invariants
• Function Specification
  • getL1BlockNumber
  • receive
  • fallback

Overview

Provides backwards-compatible access to the L1 block number for legacy applications. This contract is deprecated and exists solely for compatibility with the pre-Bedrock Optimism system.

Definitions

N/A

Assumptions

N/A

Invariants

N/A

Function Specification

getL1BlockNumber

Returns the latest L1 block number by querying the L1Block predeploy contract.

Parameters: None

Behavior:

• MUST call IL1Block(Predeploys.L1_BLOCK_ATTRIBUTES).number() to retrieve the L1 block number
• MUST return the L1 block number as a uint256

receive

Returns the L1 block number when ETH is sent to the contract without calldata.

Parameters: None (payable function)

Behavior:

• MUST retrieve the L1 block number via getL1BlockNumber()
• MUST store the result in memory at position 0
• MUST return 32 bytes containing the L1 block number

fallback

Returns the L1 block number for any function call that does not match an existing function signature.

Parameters: None (payable function)

Behavior:

• MUST retrieve the L1 block number via getL1BlockNumber()
• MUST store the result in memory at position 0
• MUST return 32 bytes containing the L1 block number