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Solidity Tutorial: all about the Compiler

Today we are looking at the Solidity Compiler from Command Line Interface (CLI)

Define the compiler version with pragma

In Solidity, you define the compiler version using the keyword pragma solidity followed by the compiler version. There are different ways to specify the compiler version.

  • stating the version like 0.x.x . This will say that you are using the exact version specified.
  • using the ^ symbol: this will tell the compiler to use either the latest version or the current version specified.
  • You can also use the operators <, >, <= and >= to specify a range.

Available output options with the Solidity compiler

Output Components:
  --ast                AST of all source files.  
  --ast-json           AST of all source files in JSON format.
  --ast-compact-json   AST of all source files in a compact JSON format.
  --asm                EVM assembly of the contracts.
  --asm-json           EVM assembly of the contracts in JSON format.
  --opcodes            Opcodes of the contracts.
  --bin                Binary of the contracts in hex.
  --bin-runtime        Binary of the runtime part of the contracts in hex.
  --clone-bin          Binary of the clone contracts in hex.
  --abi                ABI specification of the contracts.
  --hashes             Function signature hashes of the contracts.
  --userdoc            Natspec user documentation of all contracts.
  --devdoc             Natspec developer documentation of all contracts.
  --metadata           Combined Metadata JSON whose Swarm hash is stored on-chain.
  --formal             Translated source suitable for formal analysis.

Let's have a look to the different options available.

Abstract Syntax Tree ( flag --ast )

According to the Wikipedia definition, an AST is :

the tree representation of the abstract syntactic structure of a source code written in a programming language.

Let's see a really simple example. Create a file first-contract.sol and paste the following source code into it :

pragma solidity >=0.4.16 <0.7.0;

contract MyFirstContract {

	string name = "your name";
	
}

Save it and compile it using the solc compiler via the Command Line Interface and the --ast option.

solc first-contract.sol --ast

You should obtain the following output :

======= first-contract.sol =======
PragmaDirective
   Source: "pragma solidity >=0.4.16 <0.7.0;"
ContractDefinition "MyFirstContract"
   Source: "contract MyFirstContract {\n\n\tstring name = \"your name\";\n}"
  VariableDeclaration "name"
     Type: string storage ref
     Source: "string name = \"your name\""
    ElementaryTypeName string
       Source: "string"
    Literal, token: [no token] value: your name
       Type: literal_string "your name"
       Source: "\"your name\""

References

https://ethereum.stackexchange.com/questions/36704/how-to-get-an-output-similar-to-remix-in-solc-woth-opcodes-comments-from-sour