Implement lint against direct uses of rustc_type_ir in compiler crates

Author: rperier

compiler/rustc_errors/src/lib.rs

@@ -7,6 +7,7 @@
 #![allow(internal_features)]
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::untranslatable_diagnostic)]
+#![cfg_attr(not(bootstrap), allow(rustc::direct_use_of_rustc_type_ir))]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
 #![feature(array_windows)]

compiler/rustc_lint/messages.ftl

@@ -799,6 +799,9 @@ lint_tykind = usage of `ty::TyKind`
 lint_tykind_kind = usage of `ty::TyKind::<kind>`
     .suggestion = try using `ty::<kind>` directly
 
+lint_type_ir_direct_use = do not use `rustc_type_ir` unless you're inside of the trait solver or rustc_middle
+    .note = use rustc_middle instead
+
 lint_type_ir_inherent_usage = do not use `rustc_type_ir::inherent` unless you're inside of the trait solver
     .note = the method or struct you're looking for is likely defined somewhere else downstream in the compiler
 

compiler/rustc_lint/src/internal.rs

@@ -14,8 +14,8 @@ use {rustc_ast as ast, rustc_hir as hir};
 use crate::lints::{
     BadOptAccessDiag, DefaultHashTypesDiag, DiagOutOfImpl, LintPassByHand,
     NonGlobImportTypeIrInherent, QueryInstability, QueryUntracked, SpanUseEqCtxtDiag,
-    SymbolInternStringLiteralDiag, TyQualified, TykindDiag, TykindKind, TypeIrInherentUsage,
-    TypeIrTraitUsage, UntranslatableDiag,
+    SymbolInternStringLiteralDiag, TyQualified, TykindDiag, TykindKind, TypeIrDirectUse,
+    TypeIrInherentUsage, TypeIrTraitUsage, UntranslatableDiag,
 };
 use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
 
@@ -676,3 +676,26 @@ impl<'tcx> LateLintPass<'tcx> for SymbolInternStringLiteral {
         }
     }
 }
+
+declare_tool_lint! {
+    /// The `direct_use_of_rustc_type_ir` lint detects usage of `rustc_type_ir`.
+    ///
+    /// This module should only be used within the trait solver and some desirable
+    /// crates like rustc_middle.
+    pub rustc::DIRECT_USE_OF_RUSTC_TYPE_IR,
+    Allow,
+    "usage `rustc_type_ir` abstraction outside of trait system",
+    report_in_external_macro: true
+}
+declare_lint_pass!(UseOfTypeIr => [DIRECT_USE_OF_RUSTC_TYPE_IR]);
+
+impl<'tcx> LateLintPass<'tcx> for UseOfTypeIr {
+    fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx rustc_hir::Item<'tcx>) {
+        let rustc_hir::ItemKind::Use(path, _) = item.kind else { return };
+        if let Some(segment) = path.segments.first()
+            && segment.ident.to_string() == "rustc_type_ir"
+        {
+            cx.emit_span_lint(DIRECT_USE_OF_RUSTC_TYPE_IR, item.span, TypeIrDirectUse);
+        }
+    }
+}

compiler/rustc_lint/src/lib.rs

@@ -638,6 +638,8 @@ fn register_internals(store: &mut LintStore) {
     store.register_late_mod_pass(|_| Box::new(SpanUseEqCtxt));
     store.register_lints(&SymbolInternStringLiteral::lint_vec());
     store.register_late_mod_pass(|_| Box::new(SymbolInternStringLiteral));
+    store.register_lints(&UseOfTypeIr::lint_vec());
+    store.register_late_mod_pass(|_| Box::new(UseOfTypeIr));
     // FIXME(davidtwco): deliberately do not include `UNTRANSLATABLE_DIAGNOSTIC` and
     // `DIAGNOSTIC_OUTSIDE_OF_IMPL` here because `-Wrustc::internal` is provided to every crate and
     // these lints will trigger all of the time - change this once migration to diagnostic structs
@@ -659,6 +661,7 @@ fn register_internals(store: &mut LintStore) {
             LintId::of(USAGE_OF_TYPE_IR_TRAITS),
             LintId::of(BAD_OPT_ACCESS),
             LintId::of(SPAN_USE_EQ_CTXT),
+            LintId::of(DIRECT_USE_OF_RUSTC_TYPE_IR),
         ],
     );
 }

compiler/rustc_lint/src/lints.rs

@@ -995,6 +995,11 @@ pub(crate) struct TypeIrInherentUsage;
 #[note]
 pub(crate) struct TypeIrTraitUsage;
 
+#[derive(LintDiagnostic)]
+#[diag(lint_type_ir_direct_use)]
+#[note]
+pub(crate) struct TypeIrDirectUse;
+
 #[derive(LintDiagnostic)]
 #[diag(lint_non_glob_import_type_ir_inherent)]
 pub(crate) struct NonGlobImportTypeIrInherent {

compiler/rustc_middle/src/lib.rs

@@ -28,6 +28,7 @@
 #![allow(internal_features)]
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::untranslatable_diagnostic)]
+#![cfg_attr(not(bootstrap), allow(rustc::direct_use_of_rustc_type_ir))]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
 #![feature(allocator_api)]

compiler/rustc_next_trait_solver/src/lib.rs

@@ -7,6 +7,7 @@
 // tidy-alphabetical-start
 #![allow(rustc::usage_of_type_ir_inherent)]
 #![allow(rustc::usage_of_type_ir_traits)]
+#![cfg_attr(not(bootstrap), allow(rustc::direct_use_of_rustc_type_ir))]
 // tidy-alphabetical-end
 
 pub mod canonicalizer;

compiler/rustc_type_ir/src/lib.rs

@@ -7,6 +7,7 @@
     feature(associated_type_defaults, never_type, rustc_attrs, negative_impls)
 )]
 #![cfg_attr(feature = "nightly", allow(internal_features))]
+#![cfg_attr(not(bootstrap), allow(rustc::direct_use_of_rustc_type_ir))]
 // tidy-alphabetical-end
 
 extern crate self as rustc_type_ir;

tests/ui-fulldeps/internal-lints/direct-use-of-rustc-type-ir.rs

@@ -0,0 +1,13 @@
+//@ compile-flags: -Z unstable-options
+//@ ignore-stage1
+
+#![feature(rustc_private)]
+#![deny(rustc::direct_use_of_rustc_type_ir)]
+
+extern crate rustc_type_ir;
+
+use rustc_type_ir::*;
+//~^ ERROR: do not use `rustc_type_ir` unless you're inside of the trait solver or rustc_middle
+
+
+fn main() {}

tests/ui-fulldeps/internal-lints/direct-use-of-rustc-type-ir.stderr

@@ -0,0 +1,15 @@
+error: do not use `rustc_type_ir` unless you're inside of the trait solver or rustc_middle
+  --> $DIR/direct-use-of-rustc-type-ir.rs:9:1
+   |
+LL | use rustc_type_ir::*;
+   | ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: use rustc_middle instead
+note: the lint level is defined here
+  --> $DIR/direct-use-of-rustc-type-ir.rs:5:9
+   |
+LL | #![deny(rustc::direct_use_of_rustc_type_ir)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+