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`

Author: nnethercote

clippy_lints/src/functions.rs

@@ -239,7 +239,7 @@ impl<'tcx> LateLintPass<'tcx> for Functions {
                 return;
             }
             if cx.access_levels.is_exported(item.hir_id)
-                && !is_proc_macro(&item.attrs)
+                && !is_proc_macro(cx.sess(), &item.attrs)
                 && attr_by_name(&item.attrs, "no_mangle").is_none()
             {
                 check_must_use_candidate(
@@ -262,7 +262,7 @@ impl<'tcx> LateLintPass<'tcx> for Functions {
                 let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
                 check_needless_must_use(cx, &sig.decl, item.hir_id, item.span, fn_header_span, attr);
             } else if cx.access_levels.is_exported(item.hir_id)
-                && !is_proc_macro(&item.attrs)
+                && !is_proc_macro(cx.sess(), &item.attrs)
                 && trait_ref_of_method(cx, item.hir_id).is_none()
             {
                 check_must_use_candidate(
@@ -294,7 +294,7 @@ impl<'tcx> LateLintPass<'tcx> for Functions {
                 let body = cx.tcx.hir().body(eid);
                 Self::check_raw_ptr(cx, sig.header.unsafety, &sig.decl, body, item.hir_id);
 
-                if attr.is_none() && cx.access_levels.is_exported(item.hir_id) && !is_proc_macro(&item.attrs) {
+                if attr.is_none() && cx.access_levels.is_exported(item.hir_id) && !is_proc_macro(cx.sess(), &item.attrs) {
                     check_must_use_candidate(
                         cx,
                         &sig.decl,

clippy_lints/src/manual_non_exhaustive.rs

@@ -102,7 +102,7 @@ fn check_manual_non_exhaustive_enum(cx: &EarlyContext<'_>, item: &Item, variants
                 "this seems like a manual implementation of the non-exhaustive pattern",
                 |diag| {
                     if_chain! {
-                        if !attr::contains_name(&item.attrs, sym!(non_exhaustive));
+                        if !item.attrs.iter().any(|attr| attr.has_name(sym!(non_exhaustive)));
                         let header_span = cx.sess.source_map().span_until_char(item.span, '{');
                         if let Some(snippet) = snippet_opt(cx, header_span);
                         then {
@@ -154,7 +154,7 @@ fn check_manual_non_exhaustive_struct(cx: &EarlyContext<'_>, item: &Item, data:
                 "this seems like a manual implementation of the non-exhaustive pattern",
                 |diag| {
                     if_chain! {
-                        if !attr::contains_name(&item.attrs, sym!(non_exhaustive));
+                        if !item.attrs.iter().any(|attr| attr.has_name(sym!(non_exhaustive)));
                         let header_span = find_header_span(cx, item, data);
                         if let Some(snippet) = snippet_opt(cx, header_span);
                         then {

clippy_lints/src/non_expressive_names.rs

@@ -2,7 +2,6 @@ use crate::utils::{span_lint, span_lint_and_then};
 use rustc_ast::ast::{
     Arm, AssocItem, AssocItemKind, Attribute, Block, FnDecl, Item, ItemKind, Local, MacCall, Pat, PatKind,
 };
-use rustc_ast::attr;
 use rustc_ast::visit::{walk_block, walk_expr, walk_pat, Visitor};
 use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_middle::lint::in_external_macro;
@@ -385,7 +384,7 @@ impl EarlyLintPass for NonExpressiveNames {
 }
 
 fn do_check(lint: &mut NonExpressiveNames, cx: &EarlyContext<'_>, attrs: &[Attribute], decl: &FnDecl, blk: &Block) {
-    if !attr::contains_name(attrs, sym!(test)) {
+    if !attrs.iter().any(|attr| attr.has_name(sym!(test))) {
         let mut visitor = SimilarNamesLocalVisitor {
             names: Vec::new(),
             cx,

clippy_lints/src/utils/attrs.rs

@@ -1,5 +1,4 @@
 use rustc_ast::ast;
-use rustc_ast::expand::is_proc_macro_attr;
 use rustc_errors::Applicability;
 use rustc_session::Session;
 use std::str::FromStr;
@@ -126,6 +125,6 @@ fn parse_attrs<F: FnMut(u64)>(sess: &Session, attrs: &[ast::Attribute], name: &'
 
 /// Return true if the attributes contain any of `proc_macro`,
 /// `proc_macro_derive` or `proc_macro_attribute`, false otherwise
-pub fn is_proc_macro(attrs: &[ast::Attribute]) -> bool {
-    attrs.iter().any(is_proc_macro_attr)
+pub fn is_proc_macro(sess: &Session, attrs: &[ast::Attribute]) -> bool {
+    attrs.iter().any(|attr| sess.is_proc_macro_attr(attr))
 }

clippy_lints/src/utils/mod.rs

@@ -932,7 +932,7 @@ pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
 /// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
 /// implementations have.
 pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
-    attr::contains_name(attrs, sym!(automatically_derived))
+    attrs.iter().any(|attr| attr.has_name(sym!(automatically_derived)))
 }
 
 /// Remove blocks around an expression.