Add lint groups; define built-in lint groups bad_style and unused

This adds support for lint groups to the compiler. Lint groups are a way of
grouping a number of lints together under one name. For example, this also
defines a default lint for naming conventions, named `bad_style`. Writing
`#[allow(bad_style)]` is equivalent to writing
`#[allow(non_camel_case_types, non_snake_case, non_uppercase_statics)]`. These
lint groups can also be defined as a compiler plugin using the new
`Registry::register_lint_group` method.

This also adds two built-in lint groups, `bad_style` and `unused`. The contents
of these groups can be seen by running `rustc -W help`.

src/libcollections/hash/mod.rs

@@ -157,7 +157,6 @@ macro_rules! impl_hash_tuple(
 
     ( $($name:ident)+) => (
         impl<S: Writer, $($name: Hash<S>),*> Hash<S> for ($($name,)*) {
-            #[allow(uppercase_variables)]
             #[inline]
             #[allow(non_snake_case)]
             fn hash(&self, state: &mut S) {

src/libcore/ops.rs

@@ -775,7 +775,7 @@ macro_rules! def_fn_mut(
         FnMut<($($args,)*),Result>
         for extern "Rust" fn($($args: $args,)*) -> Result {
             #[rust_call_abi_hack]
-            #[allow(uppercase_variables)]
+            #[allow(non_snake_case)]
             fn call_mut(&mut self, args: ($($args,)*)) -> Result {
                 let ($($args,)*) = args;
                 (*self)($($args,)*)

src/librustc/driver/driver.rs

@@ -242,13 +242,17 @@ pub fn phase_2_configure_and_expand(sess: &Session,
         }
     });
 
-    let Registry { syntax_exts, lint_passes, .. } = registry;
+    let Registry { syntax_exts, lint_passes, lint_groups, .. } = registry;
 
     {
         let mut ls = sess.lint_store.borrow_mut();
         for pass in lint_passes.move_iter() {
             ls.register_pass(Some(sess), true, pass);
         }
+
+        for (name, to) in lint_groups.move_iter() {
+            ls.register_group(Some(sess), true, name, to);
+        }
     }
 
     // Lint plugins are registered; now we can process command line flags.

src/librustc/driver/mod.rs

@@ -180,14 +180,26 @@ Available lint options:
         lints
     }
 
+    fn sort_lint_groups(lints: Vec<(&'static str, Vec<lint::LintId>, bool)>)
+                     -> Vec<(&'static str, Vec<lint::LintId>)> {
+        let mut lints: Vec<_> = lints.move_iter().map(|(x, y, _)| (x, y)).collect();
+        lints.sort_by(|&(x, _): &(&'static str, Vec<lint::LintId>),
+                       &(y, _): &(&'static str, Vec<lint::LintId>)| {
+            x.cmp(&y)
+        });
+        lints
+    }
+
     let (plugin, builtin) = lint_store.get_lints().partitioned(|&(_, p)| p);
     let plugin = sort_lints(plugin);
     let builtin = sort_lints(builtin);
 
-    // FIXME (#7043): We should use the width in character cells rather than
-    // the number of codepoints.
+    let (plugin_groups, builtin_groups) = lint_store.get_lint_groups().partitioned(|&(_, _, p)| p);
+    let plugin_groups = sort_lint_groups(plugin_groups);
+    let builtin_groups = sort_lint_groups(builtin_groups);
+
     let max_name_len = plugin.iter().chain(builtin.iter())
-        .map(|&s| s.name.char_len())
+        .map(|&s| s.name.width(true))
         .max().unwrap_or(0);
     let padded = |x: &str| {
         " ".repeat(max_name_len - x.char_len()).append(x)
@@ -208,16 +220,48 @@ Available lint options:
 
     print_lints(builtin);
 
-    match (loaded_plugins, plugin.len()) {
-        (false, 0) => {
-            println!("Compiler plugins can provide additional lints. To see a listing of these, \
-                      re-run `rustc -W help` with a crate filename.");
+
+
+    let max_name_len = plugin_groups.iter().chain(builtin_groups.iter())
+        .map(|&(s, _)| s.width(true))
+        .max().unwrap_or(0);
+    let padded = |x: &str| {
+        " ".repeat(max_name_len - x.char_len()).append(x)
+    };
+
+    println!("Lint groups provided by rustc:\n");
+    println!("    {}  {}", padded("name"), "sub-lints");
+    println!("    {}  {}", padded("----"), "---------");
+
+    let print_lint_groups = |lints: Vec<(&'static str, Vec<lint::LintId>)>| {
+        for (name, to) in lints.move_iter() {
+            let name = name.chars().map(|x| x.to_lowercase())
+                           .collect::<String>().replace("_", "-");
+            let desc = to.move_iter().map(|x| x.as_str()).collect::<Vec<String>>().connect(", ");
+            println!("    {}  {}",
+                     padded(name.as_slice()), desc);
         }
-        (false, _) => fail!("didn't load lint plugins but got them anyway!"),
-        (true, 0) => println!("This crate does not load any lint plugins."),
-        (true, _) => {
-            println!("Lint checks provided by plugins loaded by this crate:\n");
-            print_lints(plugin);
+        println!("\n");
+    };
+
+    print_lint_groups(builtin_groups);
+
+    match (loaded_plugins, plugin.len(), plugin_groups.len()) {
+        (false, 0, _) | (false, _, 0) => {
+            println!("Compiler plugins can provide additional lints and lint groups. To see a \
+                      listing of these, re-run `rustc -W help` with a crate filename.");
+        }
+        (false, _, _) => fail!("didn't load lint plugins but got them anyway!"),
+        (true, 0, 0) => println!("This crate does not load any lint plugins or lint groups."),
+        (true, l, g) => {
+            if l > 0 {
+                println!("Lint checks provided by plugins loaded by this crate:\n");
+                print_lints(plugin);
+            }
+            if g > 0 {
+                println!("Lint groups provided by plugins loaded by this crate:\n");
+                print_lint_groups(plugin_groups);
+            }
         }
     }
 }

src/librustc/lint/builtin.rs

@@ -736,7 +736,7 @@ impl LintPass for UnusedResult {
     }
 }
 
-declare_lint!(NON_CAMEL_CASE_TYPES, Warn,
+declare_lint!(pub NON_CAMEL_CASE_TYPES, Warn,
               "types, variants, traits and type parameters should have camel case names")
 
 pub struct NonCamelCaseTypes;
@@ -844,7 +844,7 @@ fn method_context(cx: &Context, m: &ast::Method) -> MethodContext {
     }
 }
 
-declare_lint!(NON_SNAKE_CASE, Warn,
+declare_lint!(pub NON_SNAKE_CASE, Warn,
               "methods, functions, lifetime parameters and modules should have snake case names")
 
 pub struct NonSnakeCase;
@@ -930,8 +930,8 @@ impl LintPass for NonSnakeCase {
         self.check_snake_case(cx, "trait method", t.ident, t.span);
     }
 
-    fn check_lifetime_decl(&mut self, cx: &Context, t: &ast::Lifetime) {
-        self.check_snake_case(cx, "lifetime", t.name.ident(), t.span);
+    fn check_lifetime_decl(&mut self, cx: &Context, t: &ast::LifetimeDef) {
+        self.check_snake_case(cx, "lifetime", t.lifetime.name.ident(), t.lifetime.span);
     }
 
     fn check_pat(&mut self, cx: &Context, p: &ast::Pat) {
@@ -962,7 +962,7 @@ impl LintPass for NonSnakeCase {
     }
 }
 
-declare_lint!(NON_UPPERCASE_STATICS, Allow,
+declare_lint!(pub NON_UPPERCASE_STATICS, Allow,
               "static constants should have uppercase identifiers")
 
 pub struct NonUppercaseStatics;
@@ -1143,7 +1143,7 @@ impl LintPass for UnsafeBlock {
     }
 }
 
-declare_lint!(UNUSED_MUT, Warn,
+declare_lint!(pub UNUSED_MUT, Warn,
               "detect mut variables which don't need to be mutable")
 
 pub struct UnusedMut;

src/librustc/lint/context.rs

@@ -66,6 +66,10 @@ pub struct LintStore {
 
     /// Current levels of each lint, and where they were set.
     levels: HashMap<LintId, LevelSource>,
+
+    /// Map of registered lint groups to what lints they expand to. The bool
+    /// is true if the lint group was added by a plugin.
+    lint_groups: HashMap<&'static str, (Vec<LintId>, bool)>,
 }
 
 impl LintStore {
@@ -90,13 +94,18 @@ impl LintStore {
             passes: Some(vec!()),
             by_name: HashMap::new(),
             levels: HashMap::new(),
+            lint_groups: HashMap::new(),
         }
     }
 
     pub fn get_lints<'t>(&'t self) -> &'t [(&'static Lint, bool)] {
         self.lints.as_slice()
     }
 
+    pub fn get_lint_groups<'t>(&'t self) -> Vec<(&'static str, Vec<LintId>, bool)> {
+        self.lint_groups.iter().map(|(k, &(ref v, b))| (*k, v.clone(), b)).collect()
+    }
+
     pub fn register_pass(&mut self, sess: Option<&Session>,
                          from_plugin: bool, pass: LintPassObject) {
         for &lint in pass.get_lints().iter() {
@@ -123,6 +132,25 @@ impl LintStore {
         self.passes.get_mut_ref().push(pass);
     }
 
+    pub fn register_group(&mut self, sess: Option<&Session>,
+                          from_plugin: bool, name: &'static str,
+                          to: Vec<LintId>) {
+        let new = self.lint_groups.insert(name, (to, from_plugin));
+
+        if !new {
+            let msg = format!("duplicate specification of lint group {}", name);
+            match (sess, from_plugin) {
+                // We load builtin lints first, so a duplicate is a compiler bug.
+                // Use early_error when handling -W help with no crate.
+                (None, _) => early_error(msg.as_slice()),
+                (Some(sess), false) => sess.bug(msg.as_slice()),
+
+                // A duplicate name from a plugin is a user error.
+                (Some(sess), true)  => sess.err(msg.as_slice()),
+            }
+        }
+    }
+
     pub fn register_builtin(&mut self, sess: Option<&Session>) {
         macro_rules! add_builtin ( ( $sess:ident, $($name:ident),*, ) => (
             {$(
@@ -136,6 +164,10 @@ impl LintStore {
             )*}
         ))
 
+        macro_rules! add_lint_group ( ( $sess:ident, $name:expr, $($lint:ident),* ) => (
+            self.register_group($sess, false, $name, vec![$(LintId::of(builtin::$lint)),*]);
+        ))
+
         add_builtin!(sess,
                      HardwiredLints,
                      WhileTrue,
@@ -162,6 +194,13 @@ impl LintStore {
                               MissingDoc,
         )
 
+        add_lint_group!(sess, "bad_style",
+                        NON_CAMEL_CASE_TYPES, NON_SNAKE_CASE, NON_UPPERCASE_STATICS)
+
+        add_lint_group!(sess, "unused",
+                        UNUSED_IMPORTS, UNUSED_VARIABLE, DEAD_ASSIGNMENT, DEAD_CODE,
+                        UNUSED_MUT, UNREACHABLE_CODE)
+
         // We have one lint pass defined in this module.
         self.register_pass(sess, false, box GatherNodeLevels as LintPassObject);
     }
@@ -170,8 +209,20 @@ impl LintStore {
         for &(ref lint_name, level) in sess.opts.lint_opts.iter() {
             match self.by_name.find_equiv(&lint_name.as_slice()) {
                 Some(&lint_id) => self.set_level(lint_id, (level, CommandLine)),
-                None => sess.err(format!("unknown {} flag: {}",
-                                         level.as_str(), lint_name).as_slice()),
+                None => {
+                    match self.lint_groups.iter().map(|(&x, &(ref y, _))| (x, y.clone()))
+                                                 .collect::<HashMap<&'static str, Vec<LintId>>>()
+                                                 .find_equiv(&lint_name.as_slice()) {
+                        Some(v) => {
+                            v.iter()
+                             .map(|lint_id: &LintId|
+                                     self.set_level(*lint_id, (level, CommandLine)))
+                             .collect::<Vec<()>>();
+                        }
+                        None => sess.err(format!("unknown {} flag: {}",
+                                                 level.as_str(), lint_name).as_slice()),
+                    }
+                }
             }
         }
     }
@@ -305,7 +356,7 @@ impl<'a> Context<'a> {
             krate: krate,
             exported_items: exported_items,
             lints: lint_store,
-            level_stack: vec!(),
+            level_stack: vec![],
             node_levels: RefCell::new(HashMap::new()),
         }
     }
@@ -359,35 +410,46 @@ impl<'a> Context<'a> {
         let mut pushed = 0u;
 
         for result in gather_attrs(attrs).move_iter() {
-            let (lint_id, level, span) = match result {
+            let v = match result {
                 Err(span) => {
                     self.tcx.sess.span_err(span, "malformed lint attribute");
                     continue;
                 }
                 Ok((lint_name, level, span)) => {
                     match self.lints.by_name.find_equiv(&lint_name.get()) {
-                        Some(&lint_id) => (lint_id, level, span),
+                        Some(&lint_id) => vec![(lint_id, level, span)],
                         None => {
-                            self.span_lint(builtin::UNRECOGNIZED_LINT, span,
-                                           format!("unknown `{}` attribute: `{}`",
-                                                   level.as_str(), lint_name).as_slice());
-                            continue;
+                            match self.lints.lint_groups.find_equiv(&lint_name.get()) {
+                                Some(&(ref v, _)) => v.iter()
+                                                      .map(|lint_id: &LintId|
+                                                           (*lint_id, level, span))
+                                                      .collect(),
+                                None => {
+                                    self.span_lint(builtin::UNRECOGNIZED_LINT, span,
+                                               format!("unknown `{}` attribute: `{}`",
+                                                       level.as_str(), lint_name).as_slice());
+                                    continue;
+                                }
+                            }
                         }
                     }
                 }
             };
 
-            let now = self.lints.get_level_source(lint_id).val0();
-            if now == Forbid && level != Forbid {
-                let lint_name = lint_id.as_str();
-                self.tcx.sess.span_err(span,
-                                       format!("{}({}) overruled by outer forbid({})",
-                                               level.as_str(), lint_name, lint_name).as_slice());
-            } else if now != level {
-                let src = self.lints.get_level_source(lint_id).val1();
-                self.level_stack.push((lint_id, (now, src)));
-                pushed += 1;
-                self.lints.set_level(lint_id, (level, Node(span)));
+            for (lint_id, level, span) in v.move_iter() {
+                let now = self.lints.get_level_source(lint_id).val0();
+                if now == Forbid && level != Forbid {
+                    let lint_name = lint_id.as_str();
+                    self.tcx.sess.span_err(span,
+                                           format!("{}({}) overruled by outer forbid({})",
+                                                   level.as_str(), lint_name,
+                                                   lint_name).as_slice());
+                } else if now != level {
+                    let src = self.lints.get_level_source(lint_id).val1();
+                    self.level_stack.push((lint_id, (now, src)));
+                    pushed += 1;
+                    self.lints.set_level(lint_id, (level, Node(span)));
+                }
             }
         }
 

src/librustc/middle/typeck/infer/equate.rs

@@ -27,7 +27,7 @@ pub struct Equate<'f> {
     fields: CombineFields<'f>
 }
 
-#[allow(non_snake_case_functions)]
+#[allow(non_snake_case)]
 pub fn Equate<'f>(cf: CombineFields<'f>) -> Equate<'f> {
     Equate { fields: cf }
 }

src/librustc/middle/typeck/infer/glb.rs

@@ -34,7 +34,7 @@ pub struct Glb<'f> {
     fields: CombineFields<'f>
 }
 
-#[allow(non_snake_case_functions)]
+#[allow(non_snake_case)]
 pub fn Glb<'f>(cf: CombineFields<'f>) -> Glb<'f> {
     Glb { fields: cf }
 }

src/librustc/middle/typeck/infer/lub.rs

@@ -33,7 +33,7 @@ pub struct Lub<'f> {
     fields: CombineFields<'f>
 }
 
-#[allow(non_snake_case_functions)]
+#[allow(non_snake_case)]
 pub fn Lub<'f>(cf: CombineFields<'f>) -> Lub<'f> {
     Lub { fields: cf }
 }

src/librustc/middle/typeck/infer/sub.rs

@@ -32,7 +32,7 @@ pub struct Sub<'f> {
     fields: CombineFields<'f>
 }
 
-#[allow(non_snake_case_functions)]
+#[allow(non_snake_case)]
 pub fn Sub<'f>(cf: CombineFields<'f>) -> Sub<'f> {
     Sub { fields: cf }
 }