diff --git a/src/librustc/lint/builtin.rs b/src/librustc/lint/builtin.rs
index 138947e8a873b..58440a526ee20 100644
--- a/src/librustc/lint/builtin.rs
+++ b/src/librustc/lint/builtin.rs
@@ -1525,6 +1525,9 @@ impl LintPass for Stability {
declare_lint!(pub UNUSED_IMPORTS, Warn,
"imports that are never used")
+declare_lint!(pub UNUSED_EXTERN_CRATE, Allow,
+ "extern crates that are never used")
+
declare_lint!(pub UNNECESSARY_QUALIFICATION, Allow,
"detects unnecessarily qualified names")
@@ -1569,6 +1572,7 @@ impl LintPass for HardwiredLints {
fn get_lints(&self) -> LintArray {
lint_array!(
UNUSED_IMPORTS,
+ UNUSED_EXTERN_CRATE,
UNNECESSARY_QUALIFICATION,
UNRECOGNIZED_LINT,
UNUSED_VARIABLE,
diff --git a/src/librustc/lint/context.rs b/src/librustc/lint/context.rs
index 26ed5cbfb2cc1..a464de49b4df5 100644
--- a/src/librustc/lint/context.rs
+++ b/src/librustc/lint/context.rs
@@ -201,7 +201,7 @@ impl LintStore {
add_lint_group!(sess, "unused",
UNUSED_IMPORTS, UNUSED_VARIABLE, DEAD_ASSIGNMENT, DEAD_CODE,
- UNUSED_MUT, UNREACHABLE_CODE)
+ UNUSED_MUT, UNREACHABLE_CODE, UNUSED_EXTERN_CRATE)
// We have one lint pass defined in this module.
self.register_pass(sess, false, box GatherNodeLevels as LintPassObject);
diff --git a/src/librustc/middle/resolve.rs b/src/librustc/middle/resolve.rs
index 854b8b9ba7711..b20f230bc3c6e 100644
--- a/src/librustc/middle/resolve.rs
+++ b/src/librustc/middle/resolve.rs
@@ -21,7 +21,7 @@ use middle::subst::{ParamSpace, FnSpace, TypeSpace};
use middle::ty::{ExplicitSelfCategory, StaticExplicitSelfCategory};
use util::nodemap::{NodeMap, DefIdSet, FnvHashMap};
-use syntax::ast::{Arm, BindByRef, BindByValue, BindingMode, Block, Crate};
+use syntax::ast::{Arm, BindByRef, BindByValue, BindingMode, Block, Crate, CrateNum};
use syntax::ast::{DeclItem, DefId, Expr, ExprAgain, ExprBreak, ExprField};
use syntax::ast::{ExprFnBlock, ExprForLoop, ExprLoop, ExprWhile, ExprMethodCall};
use syntax::ast::{ExprPath, ExprProc, ExprStruct, ExprUnboxedFn, FnDecl};
@@ -899,6 +899,7 @@ struct Resolver<'a> {
emit_errors: bool,
used_imports: HashSet<(NodeId, Namespace)>,
+ used_crates: HashSet<CrateNum>,
}
struct BuildReducedGraphVisitor<'a, 'b:'a> {
@@ -987,6 +988,7 @@ impl<'a> Resolver<'a> {
export_map2: RefCell::new(NodeMap::new()),
trait_map: NodeMap::new(),
used_imports: HashSet::new(),
+ used_crates: HashSet::new(),
external_exports: DefIdSet::new(),
last_private: NodeMap::new(),
@@ -2453,7 +2455,14 @@ impl<'a> Resolver<'a> {
debug!("(resolving single import) found \
import in ns {:?}", namespace);
let id = import_resolution.id(namespace);
+ // track used imports and extern crates as well
this.used_imports.insert((id, namespace));
+ match target_module.def_id.get() {
+ Some(DefId{krate: kid, ..}) => {
+ this.used_crates.insert(kid);
+ },
+ _ => {}
+ }
return BoundResult(target_module, bindings);
}
}
@@ -2496,6 +2505,11 @@ impl<'a> Resolver<'a> {
Some(module) => {
debug!("(resolving single import) found external \
module");
+ // track the module as used.
+ match module.def_id.get() {
+ Some(DefId{krate: kid, ..}) => { self.used_crates.insert(kid); },
+ _ => {}
+ }
let name_bindings =
Rc::new(Resolver::create_name_bindings_from_module(
module));
@@ -3030,6 +3044,14 @@ impl<'a> Resolver<'a> {
(_, _) => {
search_module = module_def.clone();
+ // track extern crates for unused_extern_crate lint
+ match module_def.def_id.get() {
+ Some(did) => {
+ self.used_crates.insert(did.krate);
+ }
+ _ => {}
+ }
+
// Keep track of the closest
// private module used when
// resolving this import chain.
@@ -3213,7 +3235,12 @@ impl<'a> Resolver<'a> {
Some(target) => {
debug!("(resolving item in lexical scope) using \
import resolution");
+ // track used imports and extern crates as well
self.used_imports.insert((import_resolution.id(namespace), namespace));
+ match target.target_module.def_id.get() {
+ Some(DefId{krate: kid, ..}) => { self.used_crates.insert(kid); },
+ _ => {}
+ }
return Success((target, false));
}
}
@@ -3492,7 +3519,12 @@ impl<'a> Resolver<'a> {
Some(target) => {
debug!("(resolving name in module) resolved to \
import");
+ // track used imports and extern crates as well
self.used_imports.insert((import_resolution.id(namespace), namespace));
+ match target.target_module.def_id.get() {
+ Some(DefId{krate: kid, ..}) => { self.used_crates.insert(kid); },
+ _ => {}
+ }
return Success((target, true));
}
}
@@ -5061,7 +5093,14 @@ impl<'a> Resolver<'a> {
Some(def) => {
// Found it.
let id = import_resolution.id(namespace);
+ // track imports and extern crates as well
self.used_imports.insert((id, namespace));
+ match target.target_module.def_id.get() {
+ Some(DefId{krate: kid, ..}) => {
+ self.used_crates.insert(kid);
+ },
+ _ => {}
+ }
return ImportNameDefinition(def, LastMod(AllPublic));
}
None => {
@@ -5085,6 +5124,8 @@ impl<'a> Resolver<'a> {
match module.def_id.get() {
None => {} // Continue.
Some(def_id) => {
+ // track used crates
+ self.used_crates.insert(def_id.krate);
let lp = if module.is_public {LastMod(AllPublic)} else {
LastMod(DependsOn(def_id))
};
@@ -5168,6 +5209,10 @@ impl<'a> Resolver<'a> {
},
_ => (),
}
+ match containing_module.def_id.get() {
+ Some(DefId{krate: kid, ..}) => { self.used_crates.insert(kid); },
+ _ => {}
+ }
return Some(def);
}
@@ -5787,6 +5832,10 @@ impl<'a> Resolver<'a> {
if self.trait_item_map.borrow().contains_key(&(name, did)) {
add_trait_info(&mut found_traits, did, name);
self.used_imports.insert((import.type_id, TypeNS));
+ match target.target_module.def_id.get() {
+ Some(DefId{krate: kid, ..}) => { self.used_crates.insert(kid); },
+ _ => {}
+ }
}
}
@@ -5859,10 +5908,22 @@ impl<'a> Resolver<'a> {
if vi.span == DUMMY_SP { return }
match vi.node {
- ViewItemExternCrate(..) => {} // ignore
+ ViewItemExternCrate(_, _, id) => {
+ match self.session.cstore.find_extern_mod_stmt_cnum(id)
+ {
+ Some(crate_num) => if !self.used_crates.contains(&crate_num) {
+ self.session.add_lint(lint::builtin::UNUSED_EXTERN_CRATE,
+ id,
+ vi.span,
+ "unused extern crate".to_string());
+ },
+ _ => {}
+ }
+ },
ViewItemUse(ref p) => {
match p.node {
ViewPathSimple(_, _, id) => self.finalize_import(id, p.span),
+
ViewPathList(_, ref list, _) => {
for i in list.iter() {
self.finalize_import(i.node.id(), i.span);
diff --git a/src/librustc_back/lib.rs b/src/librustc_back/lib.rs
index 5db6c72975587..e48f9df75648f 100644
--- a/src/librustc_back/lib.rs
+++ b/src/librustc_back/lib.rs
@@ -36,8 +36,6 @@
#[phase(plugin, link)]
extern crate log;
extern crate syntax;
-extern crate libc;
-extern crate flate;
extern crate serialize;
pub mod abi;
diff --git a/src/libsyntax/diagnostic.rs b/src/libsyntax/diagnostic.rs
index c026a1c97c139..78d3d86b29692 100644
--- a/src/libsyntax/diagnostic.rs
+++ b/src/libsyntax/diagnostic.rs
@@ -8,8 +8,6 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
-extern crate libc;
-
use codemap::{Pos, Span};
use codemap;
use diagnostics;
diff --git a/src/test/compile-fail/lint-unused-extern-crate.rs b/src/test/compile-fail/lint-unused-extern-crate.rs
new file mode 100644
index 0000000000000..a4dfdbdaeae01
--- /dev/null
+++ b/src/test/compile-fail/lint-unused-extern-crate.rs
@@ -0,0 +1,32 @@
+// Copyright 2014 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.
+
+#![feature(globs)]
+#![deny(unused_extern_crate)]
+#![allow(unused_variable)]
+
+extern crate libc; //~ ERROR: unused extern crate
+
+extern crate "collections" as collecs; // no error, it is used
+
+extern crate rand; // no error, the use marks it as used
+ // even if imported objects aren't used
+
+extern crate time; // no error, the use * marks it as used
+
+#[allow(unused_imports)]
+use rand::isaac::IsaacRng;
+
+use time::*;
+
+fn main() {
+ let x: collecs::vec::Vec<uint> = Vec::new();
+ let y = now();
+}