Rollup merge of #136274 - compiler-errors:sized-wf, r=lcnr

Check Sizedness of return type in WF

Still need to clean this up a bit. This should fix https://github.com/rust-lang/trait-system-refactor-initiative/issues/150.

r? lcnr

tests/rustdoc/cfg_doc_reexport.rs

@@ -1,9 +1,12 @@
 #![feature(doc_cfg)]
-#![feature(no_core)]
+#![feature(no_core, lang_items)]
 
 #![crate_name = "foo"]
 #![no_core]
 
+#[lang = "sized"]
+trait Sized {}
+
 //@ has 'foo/index.html'
 //@ has - '//dt/*[@class="stab portability"]' 'foobar'
 //@ has - '//dt/*[@class="stab portability"]' 'bar'

tests/rustdoc/cross-crate-primitive-doc.rs

@@ -2,9 +2,12 @@
 //@ compile-flags: --extern-html-root-url=primitive_doc=../ -Z unstable-options
 //@ only-linux
 
-#![feature(no_core)]
+#![feature(no_core, lang_items)]
 #![no_core]
 
+#[lang = "sized"]
+trait Sized {}
+
 extern crate primitive_doc;
 
 //@ has 'cross_crate_primitive_doc/fn.foo.html' '//a[@href="../primitive_doc/primitive.usize.html"]' 'usize'

tests/rustdoc/intra-doc/no-doc-primitive.rs

@@ -6,8 +6,13 @@
 #![rustc_coherence_is_core]
 #![crate_type = "rlib"]
 
+
 //@ has no_doc_primitive/index.html
 //! A [`char`] and its [`char::len_utf8`].
+
+#[lang = "sized"]
+trait Sized {}
+
 impl char {
     pub fn len_utf8(self) -> usize {
         42

tests/rustdoc/reexport-trait-from-hidden-111064-2.rs

@@ -1,8 +1,11 @@
 // Regression test for <https://github.com/rust-lang/rust/issues/111064>.
-#![feature(no_core)]
+#![feature(no_core, lang_items)]
 #![no_core]
 #![crate_name = "foo"]
 
+#[lang = "sized"]
+trait Sized {}
+
 //@ files "foo" "['sidebar-items.js', 'all.html', 'hidden', 'index.html', 'struct.Bar.html', \
 //        'visible']"
 //@ files "foo/hidden" "['inner']"

tests/rustdoc/safe-intrinsic.rs

@@ -1,10 +1,13 @@
 #![feature(intrinsics)]
-#![feature(no_core)]
+#![feature(no_core, lang_items)]
 #![feature(rustc_attrs)]
 
 #![no_core]
 #![crate_name = "foo"]
 
+#[lang = "sized"]
+trait Sized {}
+
 //@ has 'foo/fn.abort.html'
 //@ has - '//pre[@class="rust item-decl"]' 'pub fn abort() -> !'
 #[rustc_intrinsic]