Rollup merge of #129678 - compiler-errors:type-ir-inherent, r=fmease

Deny imports of `rustc_type_ir::inherent` outside of type ir + new trait solver

We shouldn't encourage using `rustc_type_ir::inherent` outside of the new solver[^1], though this can happen by accident due to rust-analyzer, for example. See https://github.com/rust-lang/rust/pull/127537#discussion_r1733813842 for an example in practice.

r? fmease

[^1]: Unless we go the fully radical approach of always using these inherent methods everywhere in favor of inherent methods, which would be a major overhaul of the compiler, IMO. I don't really want to consider that possibility right now, tho.

2 files changed, 49 insertions, 0 deletions

diff --git a/tests/ui-fulldeps/internal-lints/import-of-type-ir-inherent.rs b/tests/ui-fulldeps/internal-lints/import-of-type-ir-inherent.rs
new file mode 100644
index 00000000000..08d86606a6b
--- /dev/null
+++ b/tests/ui-fulldeps/internal-lints/import-of-type-ir-inherent.rs
@@ -0,0 +1,18 @@
+//@ compile-flags: -Z unstable-options
+
+// #[cfg(bootstrap)]: We can stop ignoring next beta bump; afterward this ALWAYS should run.
+//@ ignore-stage1
+
+#![feature(rustc_private)]
+#![deny(rustc::usage_of_type_ir_inherent)]
+
+extern crate rustc_type_ir;
+
+use rustc_type_ir::inherent::*;
+//~^ ERROR do not use `rustc_type_ir::inherent` unless you're inside of the trait solver
+use rustc_type_ir::inherent;
+//~^ ERROR do not use `rustc_type_ir::inherent` unless you're inside of the trait solver
+use rustc_type_ir::inherent::Predicate;
+//~^ ERROR do not use `rustc_type_ir::inherent` unless you're inside of the trait solver
+
+fn main() {}
diff --git a/tests/ui-fulldeps/internal-lints/import-of-type-ir-inherent.stderr b/tests/ui-fulldeps/internal-lints/import-of-type-ir-inherent.stderr
new file mode 100644
index 00000000000..cc6cb9170c0
--- /dev/null
+++ b/tests/ui-fulldeps/internal-lints/import-of-type-ir-inherent.stderr
@@ -0,0 +1,31 @@
+error: do not use `rustc_type_ir::inherent` unless you're inside of the trait solver
+  --> $DIR/import-of-type-ir-inherent.rs:11:20
+   |
+LL | use rustc_type_ir::inherent::*;
+   |                    ^^^^^^^^
+   |
+   = note: the method or struct you're looking for is likely defined somewhere else downstream in the compiler
+note: the lint level is defined here
+  --> $DIR/import-of-type-ir-inherent.rs:7:9
+   |
+LL | #![deny(rustc::usage_of_type_ir_inherent)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: do not use `rustc_type_ir::inherent` unless you're inside of the trait solver
+  --> $DIR/import-of-type-ir-inherent.rs:13:20
+   |
+LL | use rustc_type_ir::inherent;
+   |                    ^^^^^^^^
+   |
+   = note: the method or struct you're looking for is likely defined somewhere else downstream in the compiler
+
+error: do not use `rustc_type_ir::inherent` unless you're inside of the trait solver
+  --> $DIR/import-of-type-ir-inherent.rs:15:20
+   |
+LL | use rustc_type_ir::inherent::Predicate;
+   |                    ^^^^^^^^
+   |
+   = note: the method or struct you're looking for is likely defined somewhere else downstream in the compiler
+
+error: aborting due to 3 previous errors
+