Mark main-like functions allow(dead_code) in tests

Fixes #12327.

src/libsyntax/test.rs

@@ -14,6 +14,7 @@
 #![allow(unused_imports)]
 use self::HasTestSignature::*;
 
+use std::iter;
 use std::slice;
 use std::mem;
 use std::vec;
@@ -24,6 +25,7 @@ use codemap::{DUMMY_SP, Span, ExpnInfo, NameAndSpan, MacroAttribute};
 use codemap;
 use diagnostic;
 use config;
+use entry::{self, EntryPointType};
 use ext::base::ExtCtxt;
 use ext::build::AstBuilder;
 use ext::expand::ExpansionConfig;
@@ -177,7 +179,19 @@ impl<'a> fold::Folder for TestHarnessGenerator<'a> {
         // the one we're going to add. Only if compiling an executable.
 
         mod_folded.items = mem::replace(&mut mod_folded.items, vec![]).move_map(|item| {
+            match entry::entry_point_type(&item, self.cx.path.len() + 1) {
+                EntryPointType::MainNamed |
+                EntryPointType::MainAttr |
+                EntryPointType::Start =>
                     item.map(|ast::Item {id, ident, attrs, node, vis, span}| {
+                        let allow_str = InternedString::new("allow");
+                        let dead_code_str = InternedString::new("dead_code");
+                        let allow_dead_code_item =
+                            attr::mk_list_item(allow_str,
+                                               vec![attr::mk_word_item(dead_code_str)]);
+                        let allow_dead_code = attr::mk_attr_outer(attr::mk_attr_id(),
+                                                                  allow_dead_code_item);
+
                         ast::Item {
                             id: id,
                             ident: ident,
@@ -187,12 +201,17 @@ impl<'a> fold::Folder for TestHarnessGenerator<'a> {
                                 } else {
                                     None
                                 }
-                    }).collect(),
+                            })
+                                .chain(iter::once(allow_dead_code))
+                                .collect(),
                             node: node,
                             vis: vis,
                             span: span
                         }
-            })
+                    }),
+                EntryPointType::None |
+                EntryPointType::OtherMain => item,
+            }
         });
 
         if !tests.is_empty() || !tested_submods.is_empty() {

src/test/compile-fail/test-warns-dead-code.rs

@@ -0,0 +1,17 @@
+// Copyright 2015 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.
+
+// compile-flags: --test
+
+#![deny(dead_code)]
+
+fn dead() {} //~ error: function is never used: `dead`
+
+fn main() {}

src/test/run-pass/test-main-not-dead-attr.rs

@@ -0,0 +1,18 @@
+// Copyright 2015 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.
+
+// compile-flags: --test
+
+#![feature(main)]
+
+#![deny(dead_code)]
+
+#[main]
+fn foo() { panic!(); }

src/test/run-pass/test-main-not-dead.rs

@@ -0,0 +1,15 @@
+// Copyright 2015 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.
+
+// compile-flags: --test
+
+#![deny(dead_code)]
+
+fn main() { panic!(); }