Rollup merge of rust-lang#61545 - flip1995:internal_lints, r=oli-obk

Implement another internal lints

cc rust-lang#49509

This adds ~~two~~ one internal lint~~s~~:
1. LINT_PASS_IMPL_WITHOUT_MACRO: Make sure, that the `{declare,impl}_lint_pass` macro is used to implement lint passes. cc rust-lang#59669
2. ~~USAGE_OF_TYCTXT_AND_SPAN_ARGS: item 2 on the list in rust-lang#49509~~

~~With 2. I wasn't sure, if this lint should be applied everywhere. That means a careful review of 0955835 would be great. Also 73fb9b4 allows this lint on some functions. Should I also apply this lint there?~~

TODO (not directly relevant for review):
- [ ] rust-lang#59316 (comment) (not sure yet, if this works or how to query for `rustc_private`, since it's not in [`Features`](https://doc.rust-lang.org/nightly/nightly-rustc/syntax/feature_gate/struct.Features.html) 🤔 cc @eddyb)
- [x] rust-lang#61735 (comment)
- [x] Check explicitly for the `{declare,impl}_lint_pass!` macros

r? @oli-obk

Author: Centril

src/bootstrap/bin/rustc.rs

@@ -306,7 +306,20 @@ fn main() {
     }
 
     // This is required for internal lints.
-    cmd.arg("-Zunstable-options");
+    if let Some(crate_name) = args.windows(2).find(|a| &*a[0] == "--crate-name") {
+        let crate_name = crate_name[1].to_string_lossy();
+        if crate_name != "rustc_version"
+            && (crate_name.starts_with("rustc")
+                || crate_name.starts_with("syntax")
+                || crate_name == "arena"
+                || crate_name == "fmt_macros")
+        {
+            cmd.arg("-Zunstable-options");
+            if stage != "0" {
+                cmd.arg("-Wrustc::internal");
+            }
+        }
+    }
 
     // Force all crates compiled by this compiler to (a) be unstable and (b)
     // allow the `rustc_private` feature to link to other unstable crates

src/libarena/lib.rs

@@ -12,7 +12,6 @@
        test(no_crate_inject, attr(deny(warnings))))]
 
 #![deny(rust_2018_idioms)]
-#![deny(internal)]
 #![deny(unused_lifetimes)]
 
 #![feature(core_intrinsics)]