Warn on unused #[macro_use] imports.

Author: jseyfried

src/libproc_macro_tokens/lib.rs

@@ -59,7 +59,7 @@
 
 extern crate syntax;
 extern crate syntax_pos;
-#[macro_use] extern crate log;
+extern crate log;
 
 pub mod build;
 pub mod parse;

src/librustc/lib.rs

@@ -57,7 +57,7 @@ extern crate rustc_const_math;
 extern crate rustc_errors as errors;
 #[macro_use] extern crate log;
 #[macro_use] extern crate syntax;
-#[macro_use] extern crate syntax_pos;
+extern crate syntax_pos;
 #[macro_use] #[no_link] extern crate rustc_bitflags;
 
 extern crate serialize as rustc_serialize; // used by deriving

src/librustc_const_math/lib.rs

@@ -28,8 +28,8 @@
 #![feature(const_fn)]
 #![cfg_attr(not(stage0), feature(i128))]
 
-#[macro_use] extern crate log;
-#[macro_use] extern crate syntax;
+extern crate log;
+extern crate syntax;
 
 // SNAP: remove use of this crate
 extern crate rustc_i128;

src/librustc_driver/lib.rs

@@ -57,7 +57,6 @@ extern crate serialize;
 extern crate rustc_llvm as llvm;
 #[macro_use]
 extern crate log;
-#[macro_use]
 extern crate syntax;
 extern crate syntax_ext;
 extern crate syntax_pos;

src/librustc_errors/lib.rs

@@ -27,9 +27,7 @@
 
 extern crate serialize;
 extern crate term;
-#[macro_use]
 extern crate log;
-#[macro_use]
 extern crate libc;
 extern crate std_unicode;
 extern crate serialize as rustc_serialize; // used by deriving

src/librustc_incremental/lib.rs

@@ -30,7 +30,7 @@ extern crate rustc_data_structures;
 extern crate serialize as rustc_serialize;
 
 #[macro_use] extern crate log;
-#[macro_use] extern crate syntax;
+extern crate syntax;
 extern crate syntax_pos;
 
 extern crate rustc_i128;

src/librustc_lint/lib.rs

@@ -37,7 +37,6 @@
 #![feature(slice_patterns)]
 #![feature(staged_api)]
 
-#[macro_use]
 extern crate syntax;
 #[macro_use]
 extern crate rustc;

src/librustc_plugin/Cargo.toml

@@ -13,7 +13,6 @@ crate-type = ["dylib"]
 log = { path = "../liblog" }
 rustc = { path = "../librustc" }
 rustc_back = { path = "../librustc_back" }
-rustc_bitflags = { path = "../librustc_bitflags" }
 rustc_metadata = { path = "../librustc_metadata" }
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }

src/librustc_plugin/lib.rs

@@ -63,9 +63,8 @@
 #![feature(rustc_diagnostic_macros)]
 #![feature(rustc_private)]
 
-#[macro_use] extern crate log;
+extern crate log;
 #[macro_use] extern crate syntax;
-#[macro_use] #[no_link] extern crate rustc_bitflags;
 
 extern crate rustc;
 extern crate rustc_back;

src/librustc_resolve/build_reduced_graph.rs

@@ -552,16 +552,35 @@ impl<'a> Resolver<'a> {
             used = true; // Avoid the normal unused extern crate warning
         }
 
+        let (graph_root, arenas) = (self.graph_root, self.arenas);
+        let macro_use_directive = |span| arenas.alloc_import_directive(ImportDirective {
+            id: item.id,
+            parent: graph_root,
+            imported_module: Cell::new(Some(module)),
+            subclass: ImportDirectiveSubclass::MacroUse,
+            span: span,
+            module_path: Vec::new(),
+            vis: Cell::new(ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))),
+            expansion: expansion,
+            used: Cell::new(false),
+        });
+
         if let Some(span) = legacy_imports.import_all {
+            let directive = macro_use_directive(span);
+            self.potentially_unused_imports.push(directive);
             module.for_each_child(|ident, ns, binding| if ns == MacroNS {
-                self.legacy_import_macro(ident.name, binding, span, allow_shadowing);
+                let imported_binding = self.import(binding, directive);
+                self.legacy_import_macro(ident.name, imported_binding, span, allow_shadowing);
             });
         } else {
             for (name, span) in legacy_imports.imports {
                 let ident = Ident::with_empty_ctxt(name);
                 let result = self.resolve_ident_in_module(module, ident, MacroNS, false, None);
                 if let Ok(binding) = result {
-                    self.legacy_import_macro(name, binding, span, allow_shadowing);
+                    let directive = macro_use_directive(span);
+                    self.potentially_unused_imports.push(directive);
+                    let imported_binding = self.import(binding, directive);
+                    self.legacy_import_macro(name, imported_binding, span, allow_shadowing);
                 } else {
                     span_err!(self.session, span, E0469, "imported macro not found");
                 }