Auto merge of #56381 - kennytm:rollup, r=kennytm

Rollup of 19 pull requests

Successful merges:

 - #55011 (Add libstd Cargo feature "panic_immediate_abort")
 - #55821 (Use sort_by_cached_key when the key function is not trivial/free)
 - #56014 (add test for issue #21335)
 - #56131 (Assorted tweaks)
 - #56214 (Implement chalk unification routines)
 - #56216 (Add TryFrom<&[T]> for [T; $N] where T: Copy)
 - #56268 (Reuse the `P` in `InvocationCollector::fold_{,opt_}expr`.)
 - #56324 (Use raw_entry for more efficient interning)
 - #56336 (Clean up and streamline the pretty-printer)
 - #56337 (Fix const_fn ICE with non-const function pointer)
 - #56339 (Remove not used option)
 - #56341 (Rename conversion util; remove duplicate util in librustc_codegen_llvm.)
 - #56349 (rustc 1.30.0's linker flavor inference is a non-backwards compat change to -Clinker)
 - #56355 (Add inline attributes and add unit to CommonTypes)
 - #56360 (Optimize local linkchecker program)
 - #56364 (Fix panic with outlives in existential type)
 - #56365 (Stabilize self_struct_ctor feature.)
 - #56367 (Moved some feature gate tests to correct location)
 - #56373 (Update books)

Author: bors

.gitmodules

@@ -65,3 +65,6 @@
 [submodule "src/doc/rustc-guide"]
 	path = src/doc/rustc-guide
 	url = https://github.com/rust-lang/rustc-guide.git
+[submodule "src/doc/edition-guide"]
+	path = src/doc/edition-guide
+	url = https://github.com/rust-lang-nursery/edition-guide

src/bootstrap/doc.rs

@@ -70,6 +70,7 @@ macro_rules! book {
 book!(
     Nomicon, "src/doc/nomicon", "nomicon";
     Reference, "src/doc/reference", "reference";
+    EditionGuide, "src/doc/edition-guide", "edition-guide";
     RustdocBook, "src/doc/rustdoc", "rustdoc";
     RustcBook, "src/doc/rustc", "rustc";
     RustByExample, "src/doc/rust-by-example", "rust-by-example";