Rollup merge of #117679 - aDotInTheVoid:yes-core, r=GuillaumeGomez

tests/rustdoc-json: Avoid needless use of `no_core` and `lang_items`

See #117487 for motivation.

I've split it into three commits, depending on how much work it was to remove `#![no_core]`. The first is entirely mechanical, the second makes no logical changes but couldn't be done with find+replace, and the third required rewriting assertions no not depend on having `#![no_core]`. All of the interesting changes for review are in the third commit, so I recommend reviewing commit-by-commit.

After this, 3 tests still use `#![no_core]`:

- `./tests/rustdoc-json/primitives/primitive_impls.rs`. Uses impls on primitives, so needs to simulate core
- `./tests/rustdoc-json/primitives/local_primitive.rs`: Uses `rustc_doc_primitive`, so needs to simulate core
- `./tests/rustdoc-json/impls/auto.rs`: Uses auto traits, so needs to simulate core

But after this change, we only rely on the core-rustc boundary in tests that deliberately test those interactions.

r? ``@GuillaumeGomez``

Fixes #117487

Author: GuillaumeGomez

tests/rustdoc-json/doc_hidden_failure.rs

@@ -1,8 +1,5 @@
 // Regression test for <https://github.com/rust-lang/rust/issues/98007>.
 
-#![feature(no_core)]
-#![no_core]
-
 mod auto {
     mod action_row {
         pub struct ActionRowBuilder;

tests/rustdoc-json/enums/field_hidden.rs

@@ -1,11 +1,5 @@
 // Regression test for <https://github.com/rust-lang/rust/issues/100529>.
 
-#![no_core]
-#![feature(no_core, lang_items)]
-
-#[lang = "sized"]
-trait Sized {}
-
 // @has "$.index[*][?(@.name=='ParseError')]"
 // @has "$.index[*][?(@.name=='UnexpectedEndTag')]"
 // @is "$.index[*][?(@.name=='UnexpectedEndTag')].inner.variant.kind.tuple" [null]

tests/rustdoc-json/enums/kind.rs

@@ -1,11 +1,5 @@
 // ignore-tidy-linelength
 
-#![feature(no_core, lang_items)]
-#![no_core]
-
-#[lang = "sized"]
-trait Sized {}
-
 pub enum Foo {
     // @set Unit = "$.index[*][?(@.name=='Unit')].id"
     // @is "$.index[*][?(@.name=='Unit')].inner.variant.kind" '"plain"'

tests/rustdoc-json/enums/tuple_fields_hidden.rs

@@ -1,9 +1,3 @@
-#![feature(no_core, lang_items)]
-#![no_core]
-
-#[lang = "sized"]
-trait Sized {}
-
 // @set 1.1.0 = "$.index[*][?(@.docs=='1.1.0')].id"
 // @set 2.1.0 = "$.index[*][?(@.docs=='2.1.0')].id"
 // @set 2.1.1 = "$.index[*][?(@.docs=='2.1.1')].id"

tests/rustdoc-json/enums/use_glob.rs

@@ -1,8 +1,5 @@
 // Regression test for <https://github.com/rust-lang/rust/issues/104942>
 
-#![feature(no_core)]
-#![no_core]
-
 // @set Color = "$.index[*][?(@.name == 'Color')].id"
 pub enum Color {
     Red,

tests/rustdoc-json/enums/use_variant.rs

@@ -1,6 +1,3 @@
-#![feature(no_core)]
-#![no_core]
-
 // @set AlwaysNone = "$.index[*][?(@.name == 'AlwaysNone')].id"
 pub enum AlwaysNone {
     // @set None = "$.index[*][?(@.name == 'None')].id"

tests/rustdoc-json/fn_pointer/generics.rs

@@ -1,8 +1,5 @@
 // ignore-tidy-linelength
 
-#![feature(no_core)]
-#![no_core]
-
 // @count "$.index[*][?(@.name=='WithHigherRankTraitBounds')].inner.type_alias.type.function_pointer.decl.inputs[*]" 1
 // @is "$.index[*][?(@.name=='WithHigherRankTraitBounds')].inner.type_alias.type.function_pointer.decl.inputs[0][0]" '"val"'
 // @is "$.index[*][?(@.name=='WithHigherRankTraitBounds')].inner.type_alias.type.function_pointer.decl.inputs[0][1].borrowed_ref.lifetime" \"\'c\"

tests/rustdoc-json/fns/extern_c_variadic.rs

@@ -1,6 +1,3 @@
-#![feature(no_core)]
-#![no_core]
-
 extern "C" {
     // @is "$.index[*][?(@.name == 'not_variadic')].inner.function.decl.c_variadic" false
     pub fn not_variadic(_: i32);

tests/rustdoc-json/fns/generic_args.rs

@@ -1,8 +1,5 @@
 // ignore-tidy-linelength
 
-#![feature(no_core)]
-#![no_core]
-
 // @set foo = "$.index[*][?(@.name=='Foo')].id"
 pub trait Foo {}
 

tests/rustdoc-json/fns/generic_returns.rs

@@ -1,8 +1,5 @@
 // ignore-tidy-linelength
 
-#![feature(no_core)]
-#![no_core]
-
 // @count "$.index[*][?(@.name=='generic_returns')].inner.module.items[*]" 2
 
 // @set foo = "$.index[*][?(@.name=='Foo')].id"