From 3edccc311ef4f29c6bf8676f7a414f8b0ef9360d Mon Sep 17 00:00:00 2001
From: Brian Anderson <banderson@mozilla.com>
Date: Thu, 1 Nov 2012 15:48:37 -0700
Subject: [PATCH] Support #[cfg] on methods

---
 src/libsyntax/fold.rs                    |  1 +
 src/rustc/front/config.rs                | 28 ++++++++++++++++++
 src/test/run-pass/conditional-compile.rs | 36 +++++++++++++++++++++++-
 3 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/src/libsyntax/fold.rs b/src/libsyntax/fold.rs
index 5fe3c8feea6..8efe4c9944c 100644
--- a/src/libsyntax/fold.rs
+++ b/src/libsyntax/fold.rs
@@ -12,6 +12,7 @@ export noop_fold_pat;
 export noop_fold_mod;
 export noop_fold_ty;
 export noop_fold_block;
+export noop_fold_item_underscore;
 export wrap;
 export fold_ty_param;
 export fold_ty_params;
diff --git a/src/rustc/front/config.rs b/src/rustc/front/config.rs
index 4577b54fb5c..bd4b4712393 100644
--- a/src/rustc/front/config.rs
+++ b/src/rustc/front/config.rs
@@ -27,6 +27,7 @@ fn strip_items(crate: @ast::crate, in_cfg: in_cfg_pred)
         @{fold_mod: |a,b| fold_mod(ctxt, a, b),
           fold_block: fold::wrap(|a,b| fold_block(ctxt, a, b) ),
           fold_foreign_mod: |a,b| fold_foreign_mod(ctxt, a, b),
+          fold_item_underscore: |a,b| fold_item_underscore(ctxt, a, b),
           .. *fold::default_ast_fold()};
 
     let fold = fold::make_fold(precursor);
@@ -79,6 +80,22 @@ fn fold_foreign_mod(cx: ctxt, nm: ast::foreign_mod,
     };
 }
 
+fn fold_item_underscore(cx: ctxt, item: ast::item_, fld: fold::ast_fold) -> ast::item_ {
+    let item = match item {
+        ast::item_impl(a, b, c, Some(methods)) => {
+            let methods = methods.filter(|m| method_in_cfg(cx, *m) );
+            ast::item_impl(a, b, c, Some(methods))
+        }
+        ast::item_trait(a, b, ref methods) => {
+            let methods = methods.filter(|m| trait_method_in_cfg(cx, m) );
+            ast::item_trait(a, b, methods)
+        }
+        _ => item
+    };
+
+    fold::noop_fold_item_underscore(item, fld)
+}
+
 fn filter_stmt(cx: ctxt, &&stmt: @ast::stmt) ->
    Option<@ast::stmt> {
     match stmt.node {
@@ -118,6 +135,17 @@ fn view_item_in_cfg(cx: ctxt, item: @ast::view_item) -> bool {
     return cx.in_cfg(item.attrs);
 }
 
+fn method_in_cfg(cx: ctxt, meth: @ast::method) -> bool {
+    return cx.in_cfg(meth.attrs);
+}
+
+fn trait_method_in_cfg(cx: ctxt, meth: &ast::trait_method) -> bool {
+    match *meth {
+        ast::required(ref meth) => cx.in_cfg(meth.attrs),
+        ast::provided(@ref meth) => cx.in_cfg(meth.attrs)
+    }
+}
+
 // Determine if an item should be translated in the current crate
 // configuration based on the item's attributes
 fn in_cfg(cfg: ast::crate_cfg, attrs: ~[ast::attribute]) -> bool {
diff --git a/src/test/run-pass/conditional-compile.rs b/src/test/run-pass/conditional-compile.rs
index bc97114b581..cc2f0fec96f 100644
--- a/src/test/run-pass/conditional-compile.rs
+++ b/src/test/run-pass/conditional-compile.rs
@@ -1,3 +1,7 @@
+// Crate use statements
+#[cfg(bogus)]
+use flippity;
+
 #[cfg(bogus)]
 const b: bool = false;
 
@@ -115,4 +119,34 @@ mod test_use_statements {
         #[cfg(bogus)]
         use flippity_foo;
     }
-}
\ No newline at end of file
+}
+
+mod test_methods {
+    struct Foo {
+        bar: uint
+    }
+
+    impl Foo: Fooable {
+        #[cfg(bogus)]
+        static fn what() { }
+
+        static fn what() { }
+
+        #[cfg(bogus)]
+        fn the() { }
+
+        fn the() { }
+    }
+
+    trait Fooable {
+        #[cfg(bogus)]
+        static fn what();
+
+        static fn what();
+
+        #[cfg(bogus)]
+        fn the();
+
+        fn the();
+    }
+}