error_codes_check.rs

//! Checks that all error codes have at least one test to prevent having error
//! codes that are silently not thrown by the compiler anymore.

use std::collections::HashMap;
use std::ffi::OsStr;
use std::fs::read_to_string;
use std::path::Path;

// A few of those error codes can't be tested but all the others can and *should* be tested!
const WHITELIST: &[&str] = &[
    "E0183", "E0227", "E0279", "E0280", "E0311", "E0313", "E0314", "E0315", "E0377", "E0456",
    "E0461", "E0462", "E0464", "E0465", "E0472", "E0473", "E0474", "E0475", "E0476", "E0479",
    "E0480", "E0481", "E0482", "E0483", "E0484", "E0485", "E0486", "E0487", "E0488", "E0489",
    "E0514", "E0519", "E0523", "E0553", "E0554", "E0570", "E0629", "E0630", "E0640", "E0717",
    "E0727", "E0729",
];

// Some error codes don't have any tests apparently...
const IGNORE_EXPLANATION_CHECK: &[&str] =
    &["E0570", "E0601", "E0602", "E0639", "E0729", "E0749", "E0750", "E0751"];

fn check_error_code_explanation(
    f: &str,
    error_codes: &mut HashMap<String, bool>,
    err_code: String,
) -> bool {
    let mut invalid_compile_fail_format = false;
    let mut found_error_code = false;

    for line in f.lines() {
        let s = line.trim();
        if s.starts_with("```") {
            if s.contains("compile_fail") && s.contains('E') {
                if !found_error_code {
                    error_codes.insert(err_code.clone(), true);
                    found_error_code = true;
                }
            } else if s.contains("compile-fail") {
                invalid_compile_fail_format = true;
            }
        } else if s.starts_with("#### Note: this error code is no longer emitted by the compiler") {
            if !found_error_code {
                error_codes.get_mut(&err_code).map(|x| *x = true);
                found_error_code = true;
            }
        }
    }
    invalid_compile_fail_format
}

fn check_if_error_code_is_test_in_explanation(f: &str, err_code: &String) -> bool {
    let mut can_be_ignored = false;

    for line in f.lines() {
        let s = line.trim();
        if s.starts_with("#### Note: this error code is no longer emitted by the compiler") {
            return true;
        }
        if s.starts_with("```") {
            if s.contains("compile_fail") && s.contains(err_code) {
                return true;
            } else if s.contains("(") {
                // It's very likely that we can't actually make it fail compilation...
                can_be_ignored = true;
            }
        }
    }
    can_be_ignored
}

macro_rules! some_or_continue {
    ($e:expr) => {
        match $e {
            Some(e) => e,
            None => continue,
        }
    };
}

fn extract_error_codes(
    f: &str,
    error_codes: &mut HashMap<String, bool>,
    path: &Path,
    errors: &mut Vec<String>,
) {
    let mut reached_no_explanation = false;

    for line in f.lines() {
        let s = line.trim();
        if !reached_no_explanation && s.starts_with('E') && s.contains("include_str!(\"") {
            if let Some(err_code) = s.splitn(2, ':').next() {
                let err_code = err_code.to_owned();
                if !error_codes.contains_key(&err_code) {
                    error_codes.insert(err_code.clone(), false);
                }
                // Now we extract the tests from the markdown file!
                let md = some_or_continue!(s.splitn(2, "include_str!(\"").nth(1));
                let md_file_name = some_or_continue!(md.splitn(2, "\")").next());
                let path = some_or_continue!(path.parent())
                    .join(md_file_name)
                    .canonicalize()
                    .expect("failed to canonicalize error explanation file path");
                match read_to_string(&path) {
                    Ok(content) => {
                        if !IGNORE_EXPLANATION_CHECK.contains(&err_code.as_str())
                            && !check_if_error_code_is_test_in_explanation(&content, &err_code)
                        {
                            errors.push(format!(
                                "`{}` doesn't use its own error code in compile_fail example",
                                path.display(),
                            ));
                        }
                        if check_error_code_explanation(&content, error_codes, err_code) {
                            errors.push(format!(
                                "`{}` uses invalid tag `compile-fail` instead of `compile_fail`",
                                path.display(),
                            ));
                        }
                    }
                    Err(e) => {
                        eprintln!("Couldn't read `{}`: {}", path.display(), e);
                    }
                }
            }
        } else if reached_no_explanation && s.starts_with('E') {
            if let Some(err_code) = s.splitn(2, ',').next() {
                let err_code = err_code.to_owned();
                if !error_codes.contains_key(&err_code) {
                    // this check should *never* fail!
                    error_codes.insert(err_code, false);
                }
            }
        } else if s == ";" {
            reached_no_explanation = true;
        }
    }
}

fn extract_error_codes_from_tests(f: &str, error_codes: &mut HashMap<String, bool>) {
    for line in f.lines() {
        let s = line.trim();
        if s.starts_with("error[E") || s.starts_with("warning[E") {
            if let Some(err_code) = s.splitn(2, ']').next() {
                if let Some(err_code) = err_code.splitn(2, '[').nth(1) {
                    let nb = error_codes.entry(err_code.to_owned()).or_insert(false);
                    *nb = true;
                }
            }
        }
    }
}

pub fn check(path: &Path, bad: &mut bool) {
    let mut errors = Vec::new();
    println!("Checking which error codes lack tests...");
    let mut error_codes: HashMap<String, bool> = HashMap::new();
    super::walk(path, &mut |path| super::filter_dirs(path), &mut |entry, contents| {
        let file_name = entry.file_name();
        if file_name == "error_codes.rs" {
            extract_error_codes(contents, &mut error_codes, entry.path(), &mut errors);
        } else if entry.path().extension() == Some(OsStr::new("stderr")) {
            extract_error_codes_from_tests(contents, &mut error_codes);
        }
    });
    if errors.is_empty() {
        println!("Found {} error codes", error_codes.len());

        for (err_code, nb) in &error_codes {
            if !*nb && !WHITELIST.contains(&err_code.as_str()) {
                errors.push(format!("Error code {} needs to have at least one UI test!", err_code));
            }
        }
    }
    errors.sort();
    for err in &errors {
        eprintln!("{}", err);
    }
    println!("Found {} error codes with no tests", errors.len());
    if !errors.is_empty() {
        *bad = true;
    }
    println!("Done!");
}