How do I find out the solidity compiler version I am using?

Question

Specifically, while using Mist. When I create a contract via the Mist GUI, I want to then be able to verify the source code over at Etherscan. However, Etherscan requires that you provide the compiler version and whether or not optimizations were enabled.

• How can I find the version of the compiler for the version of Mist that I have?

• Are optimizations always enabled or always disabled?

• Does TEST-NET vs Main net make a difference?

Note: I am looking for an answer to how to find the compiler version, not the current Mist compiler version (which will change making the answer only transient).

Answer 1

Mist / Ethereum Wallet now has a built-in compiler that is not very well documented beyond screenshots in the tutorials in order to create, compile, and deploy contracts. However, the version of Mist's compiler and whether or not it is optimized is...hard to figure out.

• Go to the Mist releases page.

• Click on the release you are using. ie: 0.5.2

• Click "CODE" at the top. example link

• Click `package.json'. example link

• Look for "solc": "^0.X.X-X",. That is the version. So for Mist 0.5.2, the solc version is 0.2.1-1.

However, this does NOT necessarily solve your problem with getting verified on EtherScan. I cannot get the token code to match either, no matter what I tried (and I tried a lot). See the bottom of this comment if you want to dive in with me.

• Alex van de Sande asks EtherScan while their verify isn't working. No response.

---

If getting verified on EtherScan is important to you, then write your Solidity code wherever but compile it using Browser Solidity here: http://chriseth.github.io/browser-solidity/

Then use that bytecode to deploy. I have not tested it but the code it spits out for the sample token contract matches what EtherScan spits out. I assume that EtherScan is using that same browser-based compiler to check and verify contracts.

---

If you are using Mix IDE / Solidity, you can view the Solidity version by going (in the Mix IDE) to File/Mix/Help - > About.

---

If you are using solc / Solidity (command line interface) you can use the command web3.eth.compile which will then spit out something like:

contract = eth.compile.solidity(source).test
{
  code: '605280600c6000396000f3006000357c010000000000000000000000000000000000000000000000000000000090048063c6888fa114602e57005b60376004356041565b8060005260206000f35b6000600782029050604d565b91905056',
  info: {
    language: 'Solidity',
    languageVersion: '0',
    compilerVersion: '0.9.13',
    abiDefinition: [{
      constant: false,
      inputs: [{
        name: 'a',
        type: 'uint256'
      } ],
      name: 'multiply',
      outputs: [{
        name: 'd',
        type: 'uint256'
      } ],
      type: 'function'
    } ],
    userDoc: {
      methods: {
      }
    },
    developerDoc: {
      methods: {
      }
    },
    source: 'contract test { function multiply(uint a) returns(uint d) { return a * 7; } }'
  }
}

This will compile your code and give you information like compiler version, etc.

More Information

---

Optimization is a choice you can make. Via solc, you use the --optimize flag. You can read more about this magical optimization property here: How does the solidity optimizer work?. I think Mist is optimizing based on the fact that I had a 73% similarity when I chose "not optimized" on EtherScan and a 93% similarity when I chose optimized.

---

Contract Testing:

I have created the exact contract https://www.ethereum.org/token#the-code with no change whatsoever to the code using Mist v 0.5.2.

The contract code that Etherscan.io received / Mist sent was:

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

You can see this on EtherScan, or you can get it in Ethereum Wallet by opening the console and running TokenContract.eth.getCode('YOUR_ADDRESS_HERE_NO_0x_AT_BEGINNING'); Both Mist and EtherScan spit out the same code.

I attempted to verify maybe 20 different versions, with and without optimization, using Browser Solidity and never once is that code as short or Etherscan.io has it, nor does it start with 0x.....

Here is an example of what Browser Solidity & EtherScan give me using 0.2.1-3ad5e821 w/ optimization:

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

So....it still doesn't match what Mist supposedly sent and EtherScan received.

While doing research, I found that EtherChain may have better luck with verification. I, however, still could not get anything above ~93% similarity (using 2.1.1, optimized).

Hope this helps someone.

Answer 2

Right now there is no real easy way. I am trying to figure it out myself ;-)

When you are running a developer version in electron, you can always go to the folder running the mist code and type:

node

which then takes you to a node terminal where you can check your solidity version:

var solc = require('solc')
solc.version()

> '0.2.1-91a6b35f/.-Emscripten/clang/int linked to libethereum-'

Ideally our goal is to have mist broadcast the source code and compiler version on the network so services like etherchain and etherscan can verify it.

Last time I tried verifying the contract on the ethereum tip jar (which I deployed myself) I was only able to get to 97% similarity. I haven't had a chance to test it but I believe the difference is on parameters sent to the constructor function, as the changes only happen on the end of the file.