Update tidy check for error codes testing

Author: GuillaumeGomez

src/tools/tidy/src/error_codes_check.rs

@@ -3,6 +3,8 @@
 
 use std::collections::HashMap;
 use std::ffi::OsStr;
+use std::fs::read_to_string;
+use std::io::Read;
 use std::path::Path;
 
 // A few of those error codes can't be tested but all the others can and *should* be tested!
@@ -50,41 +52,69 @@ const WHITELIST: &[&str] = &[
     "E0729",
 ];
 
-fn extract_error_codes(f: &str, error_codes: &mut HashMap<String, bool>) {
+fn check_error_code_explanation(
+    f: &str,
+    error_codes: &mut HashMap<String, bool>,
+    err_code: String,
+) {
+    for line in f.lines() {
+        let s = line.trim();
+        if s.starts_with("```") && s.contains("compile_fail") && s.contains('E') {
+            error_codes.insert(err_code, true);
+            return;
+        } else if s.starts_with("#### Note: this error code is no longer emitted by the compiler") {
+            error_codes.get_mut(&err_code).map(|x| *x = true);
+            return;
+        }
+    }
+}
+
+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) {
     let mut reached_no_explanation = false;
-    let mut last_error_code = None;
 
     for line in f.lines() {
         let s = line.trim();
-        if s.starts_with('E') && s.ends_with(": r##\"") {
+        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();
-                last_error_code = Some(err_code.clone());
                 if !error_codes.contains_key(&err_code) {
-                    error_codes.insert(err_code, false);
+                    error_codes.insert(err_code.clone(), false);
                 }
-            }
-        } else if s.starts_with("```") && s.contains("compile_fail") && s.contains('E') {
-            if let Some(err_code) = s.splitn(2, 'E').skip(1).next() {
-                if let Some(err_code) = err_code.splitn(2, ',').next() {
-                    let nb = error_codes.entry(format!("E{}", err_code)).or_insert(false);
-                    *nb = true;
+                // Now we extract the tests from the markdown file!
+                let md = some_or_continue!(s.splitn(2, "include_str!(\"").skip(1).next());
+                let md_file_name = some_or_continue!(md.splitn(2, "\")").next());
+                let path = some_or_continue!(path.parent()).join(md_file_name);
+                match read_to_string(&path) {
+                    Ok(content) => {
+                        check_error_code_explanation(
+                            &content,
+                            error_codes,
+                            err_code,
+                        );
+                    }
+                    Err(e) => {
+                        eprintln!("Couldn't read `{}`: {}", path.display(), e);
+                    }
                 }
             }
-        } else if s == ";" {
-            reached_no_explanation = true;
         } 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.starts_with("#### Note: this error code is no longer emitted by the compiler") {
-            if let Some(last) = last_error_code {
-                error_codes.get_mut(&last).map(|x| *x = true);
-            }
-            last_error_code = None;
+        } else if s == ";" {
+            reached_no_explanation = true;
         }
     }
 }
@@ -111,7 +141,7 @@ pub fn check(path: &Path, bad: &mut bool) {
                 &mut |entry, contents| {
         let file_name = entry.file_name();
         if file_name == "error_codes.rs" {
-            extract_error_codes(contents, &mut error_codes);
+            extract_error_codes(contents, &mut error_codes, entry.path());
         } else if entry.path().extension() == Some(OsStr::new("stderr")) {
             extract_error_codes_from_tests(contents, &mut error_codes);
         }