mk: Move from -D warnings to #![deny(warnings)]

This commit removes the `-D warnings` flag being passed through the makefiles to
all crates to instead be a crate attribute. We want these attributes always
applied for all our standard builds, and this is more amenable to Cargo-based
builds as well.

Note that all `deny(warnings)` attributes are gated with a `cfg(stage0)`
attribute currently to match the same semantics we have today

Author: alexcrichton

mk/target.mk

@@ -17,14 +17,6 @@ export CFG_COMPILER_HOST_TRIPLE
 export CFG_DEFAULT_LINKER
 export CFG_DEFAULT_AR
 
-# The standard libraries should be held up to a higher standard than any old
-# code, make sure that these common warnings are denied by default. These can
-# be overridden during development temporarily. For stage0, we allow warnings
-# which may be bugs in stage0 (should be fixed in stage1+)
-RUST_LIB_FLAGS_ST0 += -W warnings
-RUST_LIB_FLAGS_ST1 += -D warnings
-RUST_LIB_FLAGS_ST2 += -D warnings
-
 # Macro that generates the full list of dependencies for a crate at a particular
 # stage/target/host tuple.
 #

src/liballoc/lib.rs

@@ -70,6 +70,7 @@
        test(no_crate_inject, attr(allow(unused_variables), deny(warnings))))]
 #![no_std]
 #![needs_allocator]
+#![cfg_attr(not(stage0), deny(warnings))]
 
 #![feature(allocator)]
 #![feature(box_syntax)]

src/liballoc_jemalloc/lib.rs

@@ -16,6 +16,7 @@
             reason = "this library is unlikely to be stabilized in its current \
                       form or name",
             issue = "27783")]
+#![cfg_attr(not(stage0), deny(warnings))]
 #![feature(allocator)]
 #![feature(libc)]
 #![feature(staged_api)]

src/liballoc_system/lib.rs

@@ -12,6 +12,7 @@
 #![crate_type = "rlib"]
 #![no_std]
 #![allocator]
+#![cfg_attr(not(stage0), deny(warnings))]
 #![unstable(feature = "alloc_system",
             reason = "this library is unlikely to be stabilized in its current \
                       form or name",

src/libarena/lib.rs

@@ -27,6 +27,7 @@
        html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
        html_root_url = "https://doc.rust-lang.org/nightly/",
        test(no_crate_inject, attr(deny(warnings))))]
+#![cfg_attr(not(stage0), deny(warnings))]
 
 #![feature(alloc)]
 #![feature(core_intrinsics)]

src/libcollections/lib.rs

@@ -28,6 +28,7 @@
 
 #![allow(trivial_casts)]
 #![cfg_attr(test, allow(deprecated))] // rand
+#![cfg_attr(not(stage0), deny(warnings))]
 
 #![feature(alloc)]
 #![feature(box_patterns)]

src/libcore/lib.rs

@@ -56,6 +56,7 @@
 
 #![no_core]
 #![deny(missing_docs)]
+#![cfg_attr(not(stage0), deny(warnings))]
 
 #![feature(allow_internal_unstable)]
 #![feature(associated_type_defaults)]

src/libflate/lib.rs

@@ -22,6 +22,7 @@
        html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
        html_root_url = "https://doc.rust-lang.org/nightly/",
        test(attr(deny(warnings))))]
+#![cfg_attr(not(stage0), deny(warnings))]
 
 #![feature(libc)]
 #![feature(staged_api)]

src/libfmt_macros/lib.rs

@@ -23,6 +23,7 @@
        html_root_url = "https://doc.rust-lang.org/nightly/",
        html_playground_url = "https://play.rust-lang.org/",
        test(attr(deny(warnings))))]
+#![cfg_attr(not(stage0), deny(warnings))]
 
 #![feature(staged_api)]
 #![feature(unicode)]

src/libgraphviz/lib.rs

@@ -280,6 +280,7 @@
        html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
        html_root_url = "https://doc.rust-lang.org/nightly/",
        test(attr(allow(unused_variables), deny(warnings))))]
+#![cfg_attr(not(stage0), deny(warnings))]
 
 #![feature(str_escape)]