Highlight code in `rustc --explain` (WIP)

src/librustc_driver/Cargo.toml

@@ -32,6 +32,7 @@ rustc_resolve = { path = "../librustc_resolve" }
rustc_save_analysis = { path = "../librustc_save_analysis" }
rustc_trans = { path = "../librustc_trans" }
rustc_typeck = { path = "../librustc_typeck" }
rustc_highlight = { path = "../librustc_highlight" }
serialize = { path = "../libserialize" }
syntax = { path = "../libsyntax" }
syntax_ext = { path = "../libsyntax_ext" }

src/librustc_driver/lib.rs

@@ -30,6 +30,7 @@
#![feature(rustc_private)]
#![feature(set_stdio)]
#![feature(staged_api)]
#![feature(rustc_highlight)]

extern crate arena;
extern crate flate;
@@ -53,6 +54,7 @@ extern crate rustc_resolve;
extern crate rustc_save_analysis;
extern crate rustc_trans;
extern crate rustc_typeck;
extern crate rustc_highlight;
extern crate serialize;
extern crate rustc_llvm as llvm;
#[macro_use]
@@ -78,6 +80,7 @@ use rustc::lint::Lint;
use rustc::lint;
use rustc_metadata::locator;
use rustc_metadata::cstore::CStore;
use rustc_highlight::highlight::render_to_stdout_with_highlighting;
use rustc::util::common::time;

use serialize::json::ToJson;
@@ -349,6 +352,43 @@ pub trait CompilerCalls<'a> {
#[derive(Copy, Clone)]
pub struct RustcDefaultCalls;

fn print_msg(text: &str) {
    let mut code = String::new();
    let mut in_code = false;
    let mut code_is_rust = false;
    for (i, line) in text.split('\n').enumerate() {
        // Slice off the leading newline and print.
        if i == 0 && line.len() == 0 {
            continue;
        }
        if line.starts_with("```") {
            if in_code {
                if code_is_rust {
                    println!("rust");
                    render_to_stdout_with_highlighting(code);
                } else {
                    render_to_stdout_with_highlighting(code);
                }
                code = String::new();
                code_is_rust = false;
            } else {
                if line.starts_with("```rust") {
                    code_is_rust = true;
                }
            }
            in_code = !in_code;
            println!("```");
        } else {
            if in_code {
                code.push_str(&line);
                code.push_str("\n");
            } else {
                println!("{}", line);
            }
        }
    }
}

fn handle_explain(code: &str,
                  descriptions: &errors::registry::Registry,
                  output: ErrorOutputType) {
@@ -359,14 +399,7 @@ fn handle_explain(code: &str,
    };
    match descriptions.find_description(&normalised) {
        Some(ref description) => {
            // Slice off the leading newline and print.
            print!("{}", &(&description[1..]).split("\n").map(|x| {
                format!("{}\n", if x.starts_with("```") {
                    "```"
                } else {
                    x
                })
            }).collect::<String>());
            print_msg(description);
        }
        None => {
            early_error(output, &format!("no extended information for {}", code));

src/librustc_highlight/Cargo.toml

@@ -0,0 +1,14 @@
[package]
authors = ["The Rust Project Developers"]
name = "rustc_highlight"
version = "0.0.0"

[lib]
name = "rustc_highlight"
path = "lib.rs"
crate-type = ["dylib"]

[dependencies]
syntax = { path = "../libsyntax" }
syntax_pos = { path = "../libsyntax_pos" }
log = { path = "../liblog" }