Auto merge of #134907 - Kobzol:rustc-dev-guide-josh, r=ehuss

Turn rustc-dev-guide into a Josh subtree

Discussed on [Zulip](https://rust-lang.zulipchat.com/#narrow/channel/196385-t-compiler.2Fwg-rustc-dev-guide/topic/a.20move.20to.20main.20repo.20.28rust-lang.2Frust.29).

Accompanying rustc-dev-guide PR: https://github.com/rust-lang/rustc-dev-guide/pull/2183

I didn't create a bootstrap step for rustc-dev-guide yet, because the rustc-dev-guide version that we currently use in this repo doesn't have linkcheck enabled and that fails tests.

The subtree starts with commit [ad93c5f1c49f2aeb45f7a4954017b1e607df9f5e](https://github.com/rust-lang/rustc-dev-guide/commit/ad93c5f1c49f2aeb45f7a4954017b1e607df9f5e).

What I did:
```
export DIR=src/doc/rustc-dev-guide

# Remove submodule
git submodule status ${DIR}
git submodule deinit ${DIR}
git rm -r --cached ${DIR}
rm -rf ${DIR}
# Remove rustc-dev-guide from .gitmodules
git commit -m"Removed `${DIR}` submodule"

# Import history with josh
git fetch https://github.com/rust-lang/rustc-dev-guide ad93c5f1c49f2aeb45f7a4954017b1e607df9f5e
josh-filter ':prefix=src/doc/rustc-dev-guide' FETCH_HEAD
git merge --allow-unrelated FILTERED_HEAD

# A few follow-up cleanup commits
```

r? ehuss

1 files changed, 92 insertions, 0 deletions

diff --git a/src/doc/rustc-dev-guide/examples/rustc-driver-example.rs b/src/doc/rustc-dev-guide/examples/rustc-driver-example.rs
new file mode 100644
index 00000000000..576bbcea965
--- /dev/null
+++ b/src/doc/rustc-dev-guide/examples/rustc-driver-example.rs
@@ -0,0 +1,92 @@
+#![feature(rustc_private)]
+
+extern crate rustc_ast;
+extern crate rustc_ast_pretty;
+extern crate rustc_data_structures;
+extern crate rustc_driver;
+extern crate rustc_error_codes;
+extern crate rustc_errors;
+extern crate rustc_hash;
+extern crate rustc_hir;
+extern crate rustc_interface;
+extern crate rustc_middle;
+extern crate rustc_session;
+extern crate rustc_span;
+
+use std::io;
+use std::path::Path;
+
+use rustc_ast_pretty::pprust::item_to_string;
+use rustc_data_structures::sync::Lrc;
+use rustc_driver::{Compilation, RunCompiler};
+use rustc_interface::interface::Compiler;
+use rustc_middle::ty::TyCtxt;
+
+struct MyFileLoader;
+
+impl rustc_span::source_map::FileLoader for MyFileLoader {
+    fn file_exists(&self, path: &Path) -> bool {
+        path == Path::new("main.rs")
+    }
+
+    fn read_file(&self, path: &Path) -> io::Result<String> {
+        if path == Path::new("main.rs") {
+            Ok(r#"
+fn main() {
+    let message = "Hello, World!";
+    println!("{message}");
+}
+"#
+            .to_string())
+        } else {
+            Err(io::Error::other("oops"))
+        }
+    }
+
+    fn read_binary_file(&self, _path: &Path) -> io::Result<Lrc<[u8]>> {
+        Err(io::Error::other("oops"))
+    }
+}
+
+struct MyCallbacks;
+
+impl rustc_driver::Callbacks for MyCallbacks {
+    fn after_crate_root_parsing(
+        &mut self,
+        _compiler: &Compiler,
+        krate: &rustc_ast::Crate,
+    ) -> Compilation {
+        for item in &krate.items {
+            println!("{}", item_to_string(&item));
+        }
+
+        Compilation::Continue
+    }
+
+    fn after_analysis(&mut self, _compiler: &Compiler, tcx: TyCtxt<'_>) -> Compilation {
+        // Analyze the program and inspect the types of definitions.
+        for id in tcx.hir().items() {
+            let hir = tcx.hir();
+            let item = hir.item(id);
+            match item.kind {
+                rustc_hir::ItemKind::Static(_, _, _) | rustc_hir::ItemKind::Fn(_, _, _) => {
+                    let name = item.ident;
+                    let ty = tcx.type_of(item.hir_id().owner.def_id);
+                    println!("{name:?}:\t{ty:?}")
+                }
+                _ => (),
+            }
+        }
+
+        Compilation::Stop
+    }
+}
+
+fn main() {
+    match RunCompiler::new(&["main.rs".to_string()], &mut MyCallbacks) {
+        mut compiler => {
+            compiler.set_file_loader(Some(Box::new(MyFileLoader)));
+            compiler.run();
+        }
+    }
+}