Eliminate the `SessionGlobals` from `librustc_ast`.

By moving `{known,used}_attrs` from `SessionGlobals` to `Session`. This
means they are accessed via the `Session`, rather than via TLS. A few
`Attr` methods and `librustc_ast` functions are now methods of
`Session`.

All of this required passing a `Session` to lots of functions that didn't
already have one. Some of these functions also had arguments removed, because
those arguments could be accessed directly via the `Session` argument.

`contains_feature_attr()` was dead, and is removed.

Some functions were moved from `librustc_ast` elsewhere because they now need
to access `Session`, which isn't available in that crate.
- `entry_point_type()` --> `librustc_builtin_macros`
- `global_allocator_spans()` --> `librustc_metadata`
- `is_proc_macro_attr()` --> `Session`

1 files changed, 5 insertions, 5 deletions

diff --git a/src/librustc_codegen_ssa/back/write.rs b/src/librustc_codegen_ssa/back/write.rs
index b0fae566a5a..d13c2d29d17 100644
--- a/src/librustc_codegen_ssa/back/write.rs
+++ b/src/librustc_codegen_ssa/back/write.rs
@@ -9,7 +9,6 @@ use crate::{
 
 use crate::traits::*;
 use jobserver::{Acquired, Client};
-use rustc_ast::attr;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::profiling::SelfProfilerRef;
 use rustc_data_structures::profiling::TimingGuard;
@@ -416,11 +415,12 @@ pub fn start_async_codegen<B: ExtraBackendMethods>(
 
     let crate_name = tcx.crate_name(LOCAL_CRATE);
     let crate_hash = tcx.crate_hash(LOCAL_CRATE);
-    let no_builtins = attr::contains_name(&tcx.hir().krate().item.attrs, sym::no_builtins);
+    let no_builtins = tcx.sess.contains_name(&tcx.hir().krate().item.attrs, sym::no_builtins);
     let is_compiler_builtins =
-        attr::contains_name(&tcx.hir().krate().item.attrs, sym::compiler_builtins);
-    let subsystem =
-        attr::first_attr_value_str_by_name(&tcx.hir().krate().item.attrs, sym::windows_subsystem);
+        tcx.sess.contains_name(&tcx.hir().krate().item.attrs, sym::compiler_builtins);
+    let subsystem = tcx
+        .sess
+        .first_attr_value_str_by_name(&tcx.hir().krate().item.attrs, sym::windows_subsystem);
     let windows_subsystem = subsystem.map(|subsystem| {
         if subsystem != sym::windows && subsystem != sym::console {
             tcx.sess.fatal(&format!(