Add metadata output to the diagnostics system.

Diagnostic errors are now checked for uniqueness across the compiler and
error metadata is written to JSON files.

src/librustc/diagnostics.rs

@@ -517,5 +517,3 @@ register_diagnostics! {
     E0316, // nested quantification of lifetimes
     E0370  // discriminant overflow
 }
-
-__build_diagnostic_array! { DIAGNOSTICS }

src/librustc/lib.rs

@@ -161,3 +161,9 @@ pub mod lib {
 mod rustc {
     pub use lint;
 }
+
+// Build the diagnostics array at the end so that the metadata includes error use sites.
+#[cfg(stage0)]
+__build_diagnostic_array! { DIAGNOSTICS }
+#[cfg(not(stage0))]
+__build_diagnostic_array! { librustc, DIAGNOSTICS }

src/librustc_borrowck/diagnostics.rs

@@ -13,5 +13,3 @@
 register_diagnostics! {
     E0373 // closure may outlive current fn, but it borrows {}, which is owned by current fn
 }
-
-__build_diagnostic_array! { DIAGNOSTICS }

src/librustc_borrowck/lib.rs

@@ -47,3 +47,8 @@ pub mod diagnostics;
 mod borrowck;
 
 pub mod graphviz;
+
+#[cfg(stage0)]
+__build_diagnostic_array! { DIAGNOSTICS }
+#[cfg(not(stage0))]
+__build_diagnostic_array! { librustc_borrowck, DIAGNOSTICS }

src/librustc_driver/lib.rs

@@ -854,9 +854,10 @@ pub fn diagnostics_registry() -> diagnostics::registry::Registry {
     use syntax::diagnostics::registry::Registry;
 
     let all_errors = Vec::new() +
-        &rustc::diagnostics::DIAGNOSTICS[..] +
-        &rustc_typeck::diagnostics::DIAGNOSTICS[..] +
-        &rustc_resolve::diagnostics::DIAGNOSTICS[..];
+        &rustc::DIAGNOSTICS[..] +
+        &rustc_typeck::DIAGNOSTICS[..] +
+        &rustc_borrowck::DIAGNOSTICS[..] +
+        &rustc_resolve::DIAGNOSTICS[..];
 
     Registry::new(&*all_errors)
 }

src/librustc_resolve/diagnostics.rs

@@ -28,5 +28,3 @@ register_diagnostics! {
     E0364, // item is private
     E0365  // item is private
 }
-
-__build_diagnostic_array! { DIAGNOSTICS }

src/librustc_resolve/lib.rs

@@ -3580,3 +3580,8 @@ pub fn resolve_crate<'a, 'tcx>(session: &'a Session,
                     },
     }
 }
+
+#[cfg(stage0)]
+__build_diagnostic_array! { DIAGNOSTICS }
+#[cfg(not(stage0))]
+__build_diagnostic_array! { librustc_resolve, DIAGNOSTICS }

src/librustc_typeck/diagnostics.rs

@@ -183,5 +183,3 @@ register_diagnostics! {
     E0371, // impl Trait for Trait is illegal
     E0372  // impl Trait for Trait where Trait is not object safe
 }
-
-__build_diagnostic_array! { DIAGNOSTICS }

src/librustc_typeck/lib.rs

@@ -344,3 +344,8 @@ pub fn check_crate(tcx: &ty::ctxt, trait_map: ty::TraitMap) {
     check_for_entry_fn(&ccx);
     tcx.sess.abort_if_errors();
 }
+
+#[cfg(stage0)]
+__build_diagnostic_array! { DIAGNOSTICS }
+#[cfg(not(stage0))]
+__build_diagnostic_array! { librustc_typeck, DIAGNOSTICS }

src/libsyntax/diagnostics/metadata.rs

@@ -0,0 +1,155 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! This module contains utilities for outputting metadata for diagnostic errors.
+//!
+//! Each set of errors is mapped to a metadata file by a name, which is
+//! currently always a crate name.
+
+use std::collections::BTreeMap;
+use std::env;
+use std::path::PathBuf;
+use std::fs::{read_dir, create_dir_all, OpenOptions, File};
+use std::io::{Read, Write};
+use std::error::Error;
+use rustc_serialize::json::{self, as_json};
+
+use codemap::Span;
+use ext::base::ExtCtxt;
+use diagnostics::plugin::{ErrorMap, ErrorInfo};
+
+pub use self::Uniqueness::*;
+
+// Default metadata directory to use for extended error JSON.
+const ERROR_METADATA_DIR_DEFAULT: &'static str = "tmp/extended-errors";
+
+// The name of the environment variable that sets the metadata dir.
+const ERROR_METADATA_VAR: &'static str = "ERROR_METADATA_DIR";
+
+/// JSON encodable/decodable version of `ErrorInfo`.
+#[derive(PartialEq, RustcDecodable, RustcEncodable)]
+pub struct ErrorMetadata {
+    pub description: Option<String>,
+    pub use_site: Option<ErrorLocation>
+}
+
+/// Mapping from error codes to metadata that can be (de)serialized.
+pub type ErrorMetadataMap = BTreeMap<String, ErrorMetadata>;
+
+/// JSON encodable error location type with filename and line number.
+#[derive(PartialEq, RustcDecodable, RustcEncodable)]
+pub struct ErrorLocation {
+    pub filename: String,
+    pub line: usize
+}
+
+impl ErrorLocation {
+    /// Create an error location from a span.
+    pub fn from_span(ecx: &ExtCtxt, sp: Span) -> ErrorLocation {
+        let loc = ecx.codemap().lookup_char_pos_adj(sp.lo);
+        ErrorLocation {
+            filename: loc.filename,
+            line: loc.line
+        }
+    }
+}
+
+/// Type for describing the uniqueness of a set of error codes, as returned by `check_uniqueness`.
+pub enum Uniqueness {
+    /// All errors in the set checked are unique according to the metadata files checked.
+    Unique,
+    /// One or more errors in the set occur in another metadata file.
+    /// This variant contains the first duplicate error code followed by the name
+    /// of the metadata file where the duplicate appears.
+    Duplicate(String, String)
+}
+
+/// Get the directory where metadata files should be stored.
+pub fn get_metadata_dir() -> PathBuf {
+    match env::var(ERROR_METADATA_VAR) {
+        Ok(v) => From::from(v),
+        Err(_) => From::from(ERROR_METADATA_DIR_DEFAULT)
+    }
+}
+
+/// Get the path where error metadata for the set named by `name` should be stored.
+fn get_metadata_path(name: &str) -> PathBuf {
+    get_metadata_dir().join(format!("{}.json", name))
+}
+
+/// Check that the errors in `err_map` aren't present in any metadata files in the
+/// metadata directory except the metadata file corresponding to `name`.
+pub fn check_uniqueness(name: &str, err_map: &ErrorMap) -> Result<Uniqueness, Box<Error>> {
+    let metadata_dir = get_metadata_dir();
+    let metadata_path = get_metadata_path(name);
+
+    // Create the error directory if it does not exist.
+    try!(create_dir_all(&metadata_dir));
+
+    // Check each file in the metadata directory.
+    for entry in try!(read_dir(&metadata_dir)) {
+        let path = try!(entry).path();
+
+        // Skip any existing file for this set.
+        if path == metadata_path {
+            continue;
+        }
+
+        // Read the metadata file into a string.
+        let mut metadata_str = String::new();
+        try!(
+            File::open(&path).and_then(|mut f|
+            f.read_to_string(&mut metadata_str))
+        );
+
+        // Parse the JSON contents.
+        let metadata: ErrorMetadataMap = try!(json::decode(&metadata_str));
+
+        // Check for duplicates.
+        for err in err_map.keys() {
+            let err_code = err.as_str();
+            if metadata.contains_key(err_code) {
+                return Ok(Duplicate(
+                    err_code.to_string(),
+                    path.to_string_lossy().into_owned()
+                ));
+            }
+        }
+    }
+
+    Ok(Unique)
+}
+
+/// Write metadata for the errors in `err_map` to disk, to a file corresponding to `name`.
+pub fn output_metadata(ecx: &ExtCtxt, name: &str, err_map: &ErrorMap)
+    -> Result<(), Box<Error>>
+{
+    let metadata_path = get_metadata_path(name);
+
+    // Open the dump file.
+    let mut dump_file = try!(OpenOptions::new()
+        .write(true)
+        .create(true)
+        .open(&metadata_path)
+    );
+
+    // Construct a serializable map.
+    let json_map = err_map.iter().map(|(k, &ErrorInfo { description, use_site })| {
+        let key = k.as_str().to_string();
+        let value = ErrorMetadata {
+            description: description.map(|n| n.as_str().to_string()),
+            use_site: use_site.map(|sp| ErrorLocation::from_span(ecx, sp))
+        };
+        (key, value)
+    }).collect::<ErrorMetadataMap>();
+
+    try!(write!(&mut dump_file, "{}", as_json(&json_map)));
+    Ok(())
+}

src/libsyntax/diagnostics/plugin.rs

@@ -14,6 +14,7 @@ use std::collections::BTreeMap;
 use ast;
 use ast::{Ident, Name, TokenTree};
 use codemap::Span;
+use diagnostics::metadata::{check_uniqueness, output_metadata, Duplicate};
 use ext::base::{ExtCtxt, MacEager, MacResult};
 use ext::build::AstBuilder;
 use parse::token;
@@ -24,32 +25,28 @@ use util::small_vector::SmallVector;
 const MAX_DESCRIPTION_WIDTH: usize = 80;
 
 thread_local! {
-    static REGISTERED_DIAGNOSTICS: RefCell<BTreeMap<Name, Option<Name>>> = {
+    static REGISTERED_DIAGNOSTICS: RefCell<ErrorMap> = {
         RefCell::new(BTreeMap::new())
     }
 }
-thread_local! {
-    static USED_DIAGNOSTICS: RefCell<BTreeMap<Name, Span>> = {
-        RefCell::new(BTreeMap::new())
-    }
+
+/// Error information type.
+pub struct ErrorInfo {
+    pub description: Option<Name>,
+    pub use_site: Option<Span>
 }
 
+/// Mapping from error codes to metadata.
+pub type ErrorMap = BTreeMap<Name, ErrorInfo>;
+
 fn with_registered_diagnostics<T, F>(f: F) -> T where
-    F: FnOnce(&mut BTreeMap<Name, Option<Name>>) -> T,
+    F: FnOnce(&mut ErrorMap) -> T,
 {
     REGISTERED_DIAGNOSTICS.with(move |slot| {
         f(&mut *slot.borrow_mut())
     })
 }
 
-fn with_used_diagnostics<T, F>(f: F) -> T where
-    F: FnOnce(&mut BTreeMap<Name, Span>) -> T,
-{
-    USED_DIAGNOSTICS.with(move |slot| {
-        f(&mut *slot.borrow_mut())
-    })
-}
-
 pub fn expand_diagnostic_used<'cx>(ecx: &'cx mut ExtCtxt,
                                    span: Span,
                                    token_tree: &[TokenTree])
@@ -58,23 +55,26 @@ pub fn expand_diagnostic_used<'cx>(ecx: &'cx mut ExtCtxt,
         (1, Some(&ast::TtToken(_, token::Ident(code, _)))) => code,
         _ => unreachable!()
     };
-    with_used_diagnostics(|diagnostics| {
-        match diagnostics.insert(code.name, span) {
-            Some(previous_span) => {
+
+    with_registered_diagnostics(|diagnostics| {
+        match diagnostics.get_mut(&code.name) {
+            // Previously used errors.
+            Some(&mut ErrorInfo { description: _, use_site: Some(previous_span) }) => {
                 ecx.span_warn(span, &format!(
                     "diagnostic code {} already used", &token::get_ident(code)
                 ));
                 ecx.span_note(previous_span, "previous invocation");
-            },
-            None => ()
-        }
-        ()
-    });
-    with_registered_diagnostics(|diagnostics| {
-        if !diagnostics.contains_key(&code.name) {
-            ecx.span_err(span, &format!(
-                "used diagnostic code {} not registered", &token::get_ident(code)
-            ));
+            }
+            // Newly used errors.
+            Some(ref mut info) => {
+                info.use_site = Some(span);
+            }
+            // Unregistered errors.
+            None => {
+                ecx.span_err(span, &format!(
+                    "used diagnostic code {} not registered", &token::get_ident(code)
+                ));
+            }
         }
     });
     MacEager::expr(ecx.expr_tuple(span, Vec::new()))
@@ -116,10 +116,14 @@ pub fn expand_register_diagnostic<'cx>(ecx: &'cx mut ExtCtxt,
                 token::get_ident(*code), MAX_DESCRIPTION_WIDTH
             ));
         }
-        raw_msg
     });
+    // Add the error to the map.
     with_registered_diagnostics(|diagnostics| {
-        if diagnostics.insert(code.name, description).is_some() {
+        let info = ErrorInfo {
+            description: description,
+            use_site: None
+        };
+        if diagnostics.insert(code.name, info).is_some() {
             ecx.span_err(span, &format!(
                 "diagnostic code {} already registered", &token::get_ident(*code)
             ));
@@ -143,19 +147,43 @@ pub fn expand_build_diagnostic_array<'cx>(ecx: &'cx mut ExtCtxt,
                                           span: Span,
                                           token_tree: &[TokenTree])
                                           -> Box<MacResult+'cx> {
-    let name = match (token_tree.len(), token_tree.get(0)) {
-        (1, Some(&ast::TtToken(_, token::Ident(ref name, _)))) => name,
+    assert_eq!(token_tree.len(), 3);
+    let (crate_name, name) = match (&token_tree[0], &token_tree[2]) {
+        (
+            // Crate name.
+            &ast::TtToken(_, token::Ident(ref crate_name, _)),
+            // DIAGNOSTICS ident.
+            &ast::TtToken(_, token::Ident(ref name, _))
+        ) => (crate_name.as_str(), name),
         _ => unreachable!()
     };
 
+    // Check uniqueness of errors and output metadata.
+    with_registered_diagnostics(|diagnostics| {
+        match check_uniqueness(crate_name, &*diagnostics) {
+            Ok(Duplicate(err, location)) => {
+                ecx.span_err(span, &format!(
+                    "error {} from `{}' also found in `{}'",
+                    err, crate_name, location
+                ));
+            },
+            Ok(_) => (),
+            Err(e) => panic!("{}", e.description())
+        }
+
+        output_metadata(&*ecx, crate_name, &*diagnostics).ok().expect("metadata output error");
+    });
+
+    // Construct the output expression.
     let (count, expr) =
         with_registered_diagnostics(|diagnostics| {
             let descriptions: Vec<P<ast::Expr>> =
-                diagnostics.iter().filter_map(|(code, description)| {
-                    description.map(|description| {
+                diagnostics.iter().filter_map(|(code, info)| {
+                    info.description.map(|description| {
                         ecx.expr_tuple(span, vec![
                             ecx.expr_str(span, token::get_name(*code)),
-                            ecx.expr_str(span, token::get_name(description))])
+                            ecx.expr_str(span, token::get_name(description))
+                        ])
                     })
                 }).collect();
             (descriptions.len(), ecx.expr_vec(span, descriptions))

src/libsyntax/lib.rs

@@ -69,6 +69,7 @@ pub mod diagnostics {
     pub mod macros;
     pub mod plugin;
     pub mod registry;
+    pub mod metadata;
 }
 
 pub mod syntax {

src/test/run-make/issue-19371/foo.rs

@@ -49,7 +49,7 @@ fn basic_sess(sysroot: PathBuf) -> Session {
     opts.output_types = vec![OutputTypeExe];
     opts.maybe_sysroot = Some(sysroot);
 
-    let descriptions = Registry::new(&rustc::diagnostics::DIAGNOSTICS);
+    let descriptions = Registry::new(&rustc::DIAGNOSTICS);
     let sess = build_session(opts, None, descriptions);
     rustc_lint::register_builtins(&mut sess.lint_store.borrow_mut(), Some(&sess));
     sess