Rollup merge of rust-lang#62735 - petrochenkov:galloc, r=alexcrichton

Turn `#[global_allocator]` into a regular attribute macro

It was a 99% macro with exception of some diagnostic details.

As a result of the change, `#[global_allocator]` now works in nested modules and even in nameless blocks.

Fixes rust-lang#44113
Fixes rust-lang#58072

Cargo.lock

@@ -2751,20 +2751,6 @@ dependencies = [
  "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
-[[package]]
-name = "rustc_allocator"
-version = "0.0.0"
-dependencies = [
- "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "rustc 0.0.0",
- "rustc_data_structures 0.0.0",
- "rustc_errors 0.0.0",
- "rustc_target 0.0.0",
- "smallvec 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "syntax 0.0.0",
- "syntax_pos 0.0.0",
-]
-
 [[package]]
 name = "rustc_apfloat"
 version = "0.0.0"
@@ -2822,7 +2808,6 @@ dependencies = [
  "num_cpus 1.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc 0.0.0",
- "rustc_allocator 0.0.0",
  "rustc_apfloat 0.0.0",
  "rustc_codegen_utils 0.0.0",
  "rustc_data_structures 0.0.0",
@@ -2883,7 +2868,6 @@ dependencies = [
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc 0.0.0",
  "rustc-rayon 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "rustc_allocator 0.0.0",
  "rustc_ast_borrowck 0.0.0",
  "rustc_codegen_utils 0.0.0",
  "rustc_data_structures 0.0.0",
@@ -2904,7 +2888,6 @@ dependencies = [
  "serialize 0.0.0",
  "smallvec 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "syntax 0.0.0",
- "syntax_ext 0.0.0",
  "syntax_pos 0.0.0",
 ]
 
@@ -2948,7 +2931,6 @@ dependencies = [
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc 0.0.0",
  "rustc-rayon 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "rustc_allocator 0.0.0",
  "rustc_ast_borrowck 0.0.0",
  "rustc_codegen_ssa 0.0.0",
  "rustc_codegen_utils 0.0.0",

src/libcore/macros.rs

@@ -1281,6 +1281,13 @@ mod builtin {
     #[rustc_macro_transparency = "semitransparent"]
     pub macro test_case($item:item) { /* compiler built-in */ }
 
+    /// Attribute macro applied to a static to register it as a global allocator.
+    #[stable(feature = "global_allocator", since = "1.28.0")]
+    #[allow_internal_unstable(rustc_attrs)]
+    #[rustc_builtin_macro]
+    #[rustc_macro_transparency = "semitransparent"]
+    pub macro global_allocator($item:item) { /* compiler built-in */ }
+
     /// Derive macro generating an impl of the trait `Clone`.
     #[rustc_builtin_macro]
     #[rustc_macro_transparency = "semitransparent"]

src/librustc/lib.rs

@@ -104,7 +104,6 @@ pub mod infer;
 pub mod lint;
 
 pub mod middle {
-    pub mod allocator;
     pub mod borrowck;
     pub mod expr_use_visitor;
     pub mod cstore;

src/librustc/middle/dead.rs

@@ -320,11 +320,6 @@ fn has_allow_dead_code_or_lang_attr(
         return true;
     }
 
-    // Don't lint about global allocators
-    if attr::contains_name(attrs, sym::global_allocator) {
-        return true;
-    }
-
     let def_id = tcx.hir().local_def_id(id);
     let cg_attrs = tcx.codegen_fn_attrs(def_id);
 

src/librustc/session/mod.rs

@@ -7,7 +7,6 @@ use rustc_data_structures::fingerprint::Fingerprint;
 
 use crate::lint;
 use crate::lint::builtin::BuiltinLintDiagnostics;
-use crate::middle::allocator::AllocatorKind;
 use crate::middle::dependency_format;
 use crate::session::config::{OutputType, PrintRequest, SwitchWithOptPath};
 use crate::session::search_paths::{PathKind, SearchPath};
@@ -27,6 +26,7 @@ use errors::emitter::HumanReadableErrorType;
 use errors::annotate_snippet_emitter_writer::{AnnotateSnippetEmitterWriter};
 use syntax::ast::{self, NodeId};
 use syntax::edition::Edition;
+use syntax::ext::allocator::AllocatorKind;
 use syntax::feature_gate::{self, AttributeType};
 use syntax::json::JsonEmitter;
 use syntax::source_map;