Key error when compiling with ABIEncoderV2 on solidity >= 0.7.2

[jeffywu]

Environment information

Brownie v1.12.2 - Python development framework for Ethereum
Compiling contracts...
  Solc version: 0.7.2
  Optimizer: Enabled  Runs: 200
  EVM Version: Istanbul
Generating build data...
 - Test
  File "brownie/_cli/__main__.py", line 64, in main
    importlib.import_module(f"brownie._cli.{cmd}").main()
  File "brownie/_cli/compile.py", line 50, in main
    proj = project.load()
  File "brownie/project/main.py", line 725, in load
    return Project(name, project_path)
  File "brownie/project/main.py", line 174, in __init__
    self.load()
  File "brownie/project/main.py", line 227, in load
    self._compile(changed, self._compiler_config, False)
  File "brownie/project/main.py", line 90, in _compile
    build_json = compiler.compile_and_format(
  File "brownie/project/compiler/__init__.py", line 142, in compile_and_format
    build_json.update(generate_build_json(input_json, output_json, compiler_data, silent))
  File "brownie/project/compiler/__init__.py", line 313, in generate_build_json
    build_json[contract_alias] = solidity._get_unique_build_json(
  File "brownie/project/compiler/solidity.py", line 246, in _get_unique_build_json
    pc_map, statement_map, branch_map = _generate_coverage_data(
  File "brownie/project/compiler/solidity.py", line 369, in _generate_coverage_data
    active_source_node = source_nodes[contract_id]
KeyError: '1'

• brownie Version: 1.12.2
• solc Version: 0.7.2 to 0.7.5
• Python Version: 3.8
• OS: linux

What was wrong?

Compiling this contract results in the error above:

pragma solidity >0.7.0;
pragma experimental ABIEncoderV2;

contract Test {
    function test() external view returns (uint256) {
        return 1;
    }
}

Removing the pragma experimental ABIEncoderV2; succeeds.
Changing the function to internal succeeds.
Changing the solc compiler to 0.7.1 succeeds (issue seems to appear on 0.7.2 and above)

[iamdefinitelyahuman]

This is likely related to #828 - changes were made to the ABI in v0.7.2 that broke Brownie in a few places.