Auto merge of #46550 - jseyfried:cleanup_builtin_hygiene, r=nrc

macros: hygienize use of `core`/`std` in builtin macros

Today, if a builtin macro wants to access an item from `core` or `std` (depending `#![no_std]`), it generates `::core::path::to::item` or `::std::path::to::item` respectively (c.f. `fn std_path()` in `libsyntax/ext/base.rs`).

This PR refactors the builtin macros to instead always emit `$crate::path::to::item` here. That is, the def site of builtin macros is taken to be in `extern crate core;` or `extern crate std;`. Since builtin macros are macros 1.0 (i.e. mostly unhygienic), changing the def site can only effect the resolution of `$crate`.

r? @nrc

4 files changed, 12 insertions, 8 deletions

diff --git a/src/libsyntax_ext/deriving/cmp/eq.rs b/src/libsyntax_ext/deriving/cmp/eq.rs
index a282ff5bd04..237c8654edf 100644
--- a/src/libsyntax_ext/deriving/cmp/eq.rs
+++ b/src/libsyntax_ext/deriving/cmp/eq.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use deriving::path_std;
 use deriving::generic::*;
 use deriving::generic::ty::*;
 
@@ -30,7 +31,7 @@ pub fn expand_deriving_eq(cx: &mut ExtCtxt,
     let trait_def = TraitDef {
         span,
         attributes: Vec::new(),
-        path: path_std!(cx, core::cmp::Eq),
+        path: path_std!(cx, cmp::Eq),
         additional_bounds: Vec::new(),
         generics: LifetimeBounds::empty(),
         is_unsafe: false,
diff --git a/src/libsyntax_ext/deriving/cmp/ord.rs b/src/libsyntax_ext/deriving/cmp/ord.rs
index 9b057aacece..1a392ac3765 100644
--- a/src/libsyntax_ext/deriving/cmp/ord.rs
+++ b/src/libsyntax_ext/deriving/cmp/ord.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use deriving::path_std;
 use deriving::generic::*;
 use deriving::generic::ty::*;
 
@@ -28,7 +29,7 @@ pub fn expand_deriving_ord(cx: &mut ExtCtxt,
     let trait_def = TraitDef {
         span,
         attributes: Vec::new(),
-        path: path_std!(cx, core::cmp::Ord),
+        path: path_std!(cx, cmp::Ord),
         additional_bounds: Vec::new(),
         generics: LifetimeBounds::empty(),
         is_unsafe: false,
@@ -38,7 +39,7 @@ pub fn expand_deriving_ord(cx: &mut ExtCtxt,
                           generics: LifetimeBounds::empty(),
                           explicit_self: borrowed_explicit_self(),
                           args: vec![borrowed_self()],
-                          ret_ty: Literal(path_std!(cx, core::cmp::Ordering)),
+                          ret_ty: Literal(path_std!(cx, cmp::Ordering)),
                           attributes: attrs,
                           is_unsafe: false,
                           unify_fieldless_variants: true,
diff --git a/src/libsyntax_ext/deriving/cmp/partial_eq.rs b/src/libsyntax_ext/deriving/cmp/partial_eq.rs
index e635c6bebcd..75db7cc1e4c 100644
--- a/src/libsyntax_ext/deriving/cmp/partial_eq.rs
+++ b/src/libsyntax_ext/deriving/cmp/partial_eq.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use deriving::{path_local, path_std};
 use deriving::generic::*;
 use deriving::generic::ty::*;
 
@@ -93,7 +94,7 @@ pub fn expand_deriving_partial_eq(cx: &mut ExtCtxt,
     let trait_def = TraitDef {
         span,
         attributes: Vec::new(),
-        path: path_std!(cx, core::cmp::PartialEq),
+        path: path_std!(cx, cmp::PartialEq),
         additional_bounds: Vec::new(),
         generics: LifetimeBounds::empty(),
         is_unsafe: false,
diff --git a/src/libsyntax_ext/deriving/cmp/partial_ord.rs b/src/libsyntax_ext/deriving/cmp/partial_ord.rs
index e7e1c108760..92183c58eb2 100644
--- a/src/libsyntax_ext/deriving/cmp/partial_ord.rs
+++ b/src/libsyntax_ext/deriving/cmp/partial_ord.rs
@@ -10,6 +10,7 @@
 
 pub use self::OrderingOp::*;
 
+use deriving::{path_local, pathvec_std, path_std};
 use deriving::generic::*;
 use deriving::generic::ty::*;
 
@@ -45,11 +46,11 @@ pub fn expand_deriving_partial_ord(cx: &mut ExtCtxt,
         } }
     }
 
-    let ordering_ty = Literal(path_std!(cx, core::cmp::Ordering));
-    let ret_ty = Literal(Path::new_(pathvec_std!(cx, core::option::Option),
+    let ordering_ty = Literal(path_std!(cx, cmp::Ordering));
+    let ret_ty = Literal(Path::new_(pathvec_std!(cx, option::Option),
                                     None,
                                     vec![Box::new(ordering_ty)],
-                                    true));
+                                    PathKind::Std));
 
     let inline = cx.meta_word(span, Symbol::intern("inline"));
     let attrs = vec![cx.attribute(span, inline)];
@@ -84,7 +85,7 @@ pub fn expand_deriving_partial_ord(cx: &mut ExtCtxt,
     let trait_def = TraitDef {
         span,
         attributes: vec![],
-        path: path_std!(cx, core::cmp::PartialOrd),
+        path: path_std!(cx, cmp::PartialOrd),
         additional_bounds: vec![],
         generics: LifetimeBounds::empty(),
         is_unsafe: false,