auto merge of #6093 : alexcrichton/rust/issue-2647, r=thestinger

Closes #2647

This way it's much easier to add lints throughout compilation correctly, and
functions on impls can alter the way lints are emitted. This involved pretty much rewriting how lints are emitted. Beforehand, only items could alter the lint settings, so whenever a lint was added it had to be associated with whatever item id it was coming from. I removed this (possibly questionably) in favor of just specifying a span and a message when adding a lint. When lint checking comes around, it looks at all the lints and sees which node with attributes best encloses it and uses that level of linting. This means that all consumer code doesn't have to deal with what item things came from (especially because functions on impls aren't items). More details of this can be found in the code (and comments).

As a bonus, I managed to greatly simplify emission of lints in resolve.rs about unused imports. Now instead of it manually tracking what the lint level is, it's all moved over into the lint module (as is to be expected).

Author: bors

src/libcore/hashmap.rs

@@ -17,7 +17,6 @@ use container::{Container, Mutable, Map, Set};
 use cmp::{Eq, Equiv};
 use hash::Hash;
 use old_iter::BaseIter;
-use hash::Hash;
 use old_iter;
 use option::{None, Option, Some};
 use rand::RngUtil;

src/librustc/back/link.rs

@@ -171,7 +171,6 @@ pub mod write {
     use back::link::{output_type_assembly, output_type_bitcode};
     use back::link::{output_type_exe, output_type_llvm_assembly};
     use back::link::{output_type_object};
-    use back::link::output_type;
     use driver::session::Session;
     use driver::session;
     use lib::llvm::llvm;

src/librustc/driver/driver.rs

@@ -22,6 +22,7 @@ use middle;
 use util::common::time;
 use util::ppaux;
 
+use core::hashmap::HashMap;
 use core::int;
 use core::io;
 use core::os;
@@ -200,9 +201,6 @@ pub fn compile_rest(sess: Session,
     crate = time(time_passes, ~"core injection", ||
         front::core_inject::maybe_inject_libcore_ref(sess, crate));
 
-    time(time_passes, ~"building lint settings table", ||
-        lint::build_settings_crate(sess, crate));
-
     let ast_map = time(time_passes, ~"ast indexing", ||
             syntax::ast_map::map_crate(sess.diagnostic(), crate));
 
@@ -709,7 +707,6 @@ pub fn build_session_(sopts: @session::options,
         &sopts.maybe_sysroot,
         sopts.target_triple,
         /*bad*/copy sopts.addl_lib_search_paths);
-    let lint_settings = lint::mk_lint_settings();
     @Session_ {
         targ_cfg: target_cfg,
         opts: sopts,
@@ -723,7 +720,7 @@ pub fn build_session_(sopts: @session::options,
         filesearch: filesearch,
         building_library: @mut false,
         working_dir: os::getcwd(),
-        lint_settings: lint_settings
+        lints: @mut HashMap::new(),
     }
 }
 

src/librustc/driver/session.rs

@@ -26,6 +26,8 @@ use syntax::{ast, codemap};
 use syntax::abi;
 use syntax;
 
+use core::hashmap::HashMap;
+
 #[deriving(Eq)]
 pub enum os { os_win32, os_macos, os_linux, os_android, os_freebsd, }
 
@@ -170,7 +172,7 @@ pub struct Session_ {
     filesearch: @filesearch::FileSearch,
     building_library: @mut bool,
     working_dir: Path,
-    lint_settings: lint::LintSettings
+    lints: @mut HashMap<ast::node_id, ~[(lint::lint, codemap::span, ~str)]>,
 }
 
 pub type Session = @Session_;
@@ -221,24 +223,12 @@ pub impl Session_ {
     fn unimpl(@self, msg: &str) -> ! {
         self.span_diagnostic.handler().unimpl(msg)
     }
-    fn span_lint_level(@self, level: lint::level, sp: span, msg: &str) {
-        match level {
-          lint::allow => { },
-          lint::warn => self.span_warn(sp, msg),
-          lint::deny | lint::forbid => {
-            self.span_err(sp, msg);
-          }
+    fn add_lint(@self, lint: lint::lint, id: ast::node_id, sp: span, msg: ~str) {
+        match self.lints.find_mut(&id) {
+            Some(arr) => { arr.push((lint, sp, msg)); return; }
+            None => {}
         }
-    }
-    fn span_lint(@self, lint_mode: lint::lint,
-                 expr_id: ast::node_id,
-                 item_id: ast::node_id,
-                 span: span,
-                 msg: &str) {
-        let level = lint::get_lint_settings_level(
-            self.lint_settings, lint_mode, expr_id, item_id);
-        let msg = fmt!("%s [-W %s]", msg, lint::get_lint_name(lint_mode));
-        self.span_lint_level(level, span, msg);
+        self.lints.insert(id, ~[(lint, sp, msg)]);
     }
     fn next_node_id(@self) -> ast::node_id {
         return syntax::parse::next_node_id(self.parse_sess);