[solc] colorized diagnostics output

[christianparpart]

This PR is a resurrection of #3046 and their related #4338 and #4340.

• ANSI coloring (termcolor): I didn't copy'n'paste the original one (which requires a additional license), but hacked together our own, that fits our needs
• SourceReferenceFormatter: greatly refactored to:
  • have improved diagnostics output format (this includes also streamlining line-truncation, as mentioned in Source Reference Formatter should truncate multi-line snippets #5169 (which we can close then).
  • support colored output
• solc: adds --color for forced colorized output and --no-color for explicitly disabling terminal-autodetection, e.g. if none of these will be given, the diagnostic output will be colored when stdout/stderr is connected to a terminal.

please note

Only the last 3 commits matter, the rest is from the rebase.

[chriseth]

Sounds good, but please split it up.

[chriseth]

Nice! We might even have a bug about this.

[christianparpart]

I too actually held back for a moment on that line, but said if that's a bug, then it was there before already, and I'd prefer to address it in a separate PR (as the base class is affected then, too).

[ekpyron]

Looks good now!

[chriseth]

I think there is still an inconsistency with regards to spacing between the errors.
This is how errors with secondary source locations are formatted:

Warning: Source file does not specify required compiler version! Consider adding "pragma solidity ^0.5.4;"
 --> /tmp/x.sol:1:1: 
  |
1 | contract c {
  | ^ (Relevant source part starts here and spans across multiple lines).
Error: Identifier already declared.
 --> /tmp/x.sol:3:1: 
  |
3 | int x = 3;}
  | ^^^^^

Note: The previous declaration is here:
 --> /tmp/x.sol:2:32: 
  |
2 | function f(uint) public pure { int x = 2;
  |                                ^^^^^

Error: No matching declaration found after argument-dependent lookup.
 --> /tmp/x.sol:5:27: 
  |
5 | function g() public pure{ f();}
  |                           ^

And this is how it looks without an error with secondary source location:

Warning: Source file does not specify required compiler version! Consider adding "pragma solidity ^0.5.4;"
 --> /tmp/x.sol:1:1: 
  |
1 | contract c {
  | ^ (Relevant source part starts here and spans across multiple lines).
Error: No matching declaration found after argument-dependent lookup.
 --> /tmp/x.sol:4:27: 
  |
4 | function g() public pure{ f();}
  |                           ^

I would have expected the secondary source location to be appended without an empty line between the main location and the secondary location.

Also we might want to add an empty line between two errors (actually this is how your screenshot in the description has it).

[ekpyron]

If we make more changes to this anyways, then I vote for changing the command line argument from --new-reporter to --fancy-reporter as @chriseth just suggested in the office ;-).

[chriseth]

Oh and another thing I just noticed: At least in the screenshot in the description, the line numbering it says t.sol:3:... but then on the left there is a 2. I think lines should be numbered starting from 1 in both cases.

[chriseth]

Ah ok, but the thing I pasted at least has it right.

[chriseth]

Output is now as follows:

> solc --new-reporter /tmp/x.sol 
Warning: This is a pre-release compiler version, please do not use it in production.

Error: No visibility specified. Did you intend to add "public"?
 --> /tmp/x.sol:2:1: 
  |
2 | function f() {}
  | ^^^^^^^^^^^^^^^

Error: No visibility specified. Did you intend to add "public"?
 --> /tmp/x.sol:6:1: 
  |
6 | function h() {}
  | ^^^^^^^^^^^^^^^

Warning: Source file does not specify required compiler version!
 --> /tmp/x.sol:1:1: 
  |
1 | contract c {
  | ^ (Relevant source part starts here and spans across multiple lines).

Error: Function with same name and arguments defined twice.
 --> /tmp/x.sol:2:1: 
  |
2 | function f() {}
  | ^^^^^^^^^^^^^^^
Note: Other declaration is here:
 --> /tmp/x.sol:5:1: 
  |
5 | function f() public pure {}
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^

Error: Overriding function changes state mutability from "pure" to "nonpayable".
 --> /tmp/x.sol:2:1: 
  |
2 | function f() {}
  | ^^^^^^^^^^^^^^^
Note: Overridden function is here:
 --> /tmp/x.sol:5:1: 
  |
5 | function f() public pure {}
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^

[ekpyron]

Looks good!

[chriseth]

I also verified that the old reporter is used with standard-json.

[chriseth]

Rebased.

[christianparpart]

P.S. @chriseth I didn't rename it to --fancy-reporter, even though I really very much liked the idea, but I'd rather prefer to see this reporter becoming standard at some point in the future (not necessarily the very next breaking release)

[chriseth]

I guess the plan is to make it the default starting from 0.6.0