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Solidity 0.6.11 Release Announcement

Posted by Solidity Team on July 7, 2020


Solidity v0.6.11 adds inheritance to NatSpec comments, improves debugging data output and fixes some minor issues with opening up calldata for non-external functions.

Notable New Features

NatSpec Inheritance and on Events

NatSpec comments are a way to describe the behaviour of a function to end-users. It also allows to provide more detailed information to developers.

One regular use-case is that you document the behaviour of an interface and then implement the interface in a derived contract. Previously, you had to repeat the documentation in the derived contract. This is now obsolete: The compiler will automatically inherit the documentation of the base function if the derived function does not provide any NatSpec tag.

If you provide any of the tags (@param, @dev, ...), then nothing will be inherited. The next release will provide a feature to explicitly inherit from a certain base also in that case, so stay tuned!

Furhermore, NatSpec is now supported on events.

// SPDX-License-Identifier: MIT
pragma solidity ^0.6.11;
interface Gathering {
  /// The address `participant` just registered for the gathering.
  event Registered(address participant);

  /// Registers `msg.sender` to take part in the gathering.
  function register() external;

contract MyGathering is Gathering {
  mapping(address => bool) public participants;

  function register() public override {
    participants[msg.sender] = true;
    emit Registered(msg.sender);

The derived contract MyGathering in the example code above will produce the following userdoc:

  "events": {
    "Registered(address)": {
      "notice": "The address `participant` just registered for the gathering."
  "kind": "user",
  "methods": {
    "register()": {
      "notice": "Registers `msg.sender` to take part in the gathering."
  "version": 1

Unit Denomination gwei

You can now use gwei as a unit denomination alongside wei, szabo, finney and ether:

reqire(msg.value >= 10 gwei);

Full Changelog

Language Features:

  • General: Add unit denomination gwei
  • Yul: Support linkersymbol builtin in standalone assembly mode to refer to library addresses.
  • Yul: Support using string literals exceeding 32 bytes as literal arguments for builtins.

Compiler Features:

  • NatSpec: Add fields kind and version to the JSON output.
  • NatSpec: Inherit tags from unique base functions if derived function does not provide any.
  • Commandline Interface: Prevent some incompatible commandline options from being used together.
  • NatSpec: Support NatSpec comments on events.
  • Yul Optimizer: Store knowledge about storage / memory after a := sload(x) / a := mload(x).
  • SMTChecker: Support external calls to unknown code.
  • Source Maps: Also tag jumps into and out of Yul functions as jumps into and out of functions.


  • NatSpec: Do not consider //// and /*** as NatSpec comments.
  • Type Checker: Disallow constructor parameters with calldata data location.
  • Type Checker: Do not disallow assigning to calldata variables.
  • Type Checker: Fix internal error related to using for applied to non-libraries.
  • Wasm backend: Fix code generation for for-loops with pre statements.
  • Wasm backend: Properly support both i32.drop and i64.drop, and remove drop.
  • Yul: Disallow the same variable to occur multiple times on the left-hand side of an assignment.
  • Yul: Fix source location of variable multi-assignment.

A big thank you to all contributors who helped make this release possible!

Download the new version of Solidity here.

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