A source constraint and the compiler actually used are different pieces of evidence.
LET’S PICTURE IT
A recipe can require an oven in a temperature range while the cook still chooses and configures the actual oven.
SEE IT FOR YOURSELF
A valid counter call, step by stepStep 1 / 4
This example begins with count zero and a request to call increment(). No real contract is deployed.
This example begins with count zero and a request to call increment(). No real contract is deployed.Execution follows the code’s input and permission rules. A website button is not the access-control mechanism.The function reads zero, calculates zero plus one, and writes one to persistent storage.The accepted state contains count one. Later reads can inspect it. Events are emitted only if the code implements them.
Animated local teaching model. No wallet, RPC or live blockchain data. Some labels and hashes are abbreviated for readability.
Read the version expression
A pragma such as ^0.8.20 permits compatible compiler versions according to Solidity’s version-constraint rules. It is not the same as pinning one exact compiler binary.
Settings affect output
Optimizer configuration, EVM target and other build settings can change generated bytecode. Reproducibility requires retaining the actual toolchain and settings, not only the pragma line.
Language behavior evolves
Compiler fixes and features can affect accepted source and output. Production code should be tested with the chosen version and target rather than assuming every permitted version is identical.
Verification needs build context
When comparing deployed code with source, use the actual compilation inputs. A matching project name and familiar syntax are weaker evidence than a documented reproducible build.
Read the example
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
contract LearningExample {
function answer() external pure returns (uint256) {
return 42;
}
}
The pragma is a constraint. The verification script records the actual compiler version used.
QUICK CHECK · NO PRESSURE
Does ^0.8.20 necessarily pin exactly compiler 0.8.20?
A range expression allows compatible versions rather than selecting one exact binary.