Split lints module to prepare for multiple lints

Author: ecstatic-morse

src/librustc_mir_build/build/mod.rs

@@ -181,7 +181,7 @@ fn mir_build(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Body<'_> {
             build::construct_const(cx, body_id, return_ty, return_ty_span)
         };
 
-        lints::check(tcx, &body, def_id);
+        lints::unconditional_recursion::check(tcx, &body, def_id);
 
         // The borrow checker will replace all the regions here with its own
         // inference variables. There's no point having non-erased regions here.

src/librustc_mir_build/lints/mod.rs

@@ -0,0 +1,6 @@
+//! Lints that run immediately after MIR building.
+//!
+//! By running these before any MIR transformations, we ensure that the MIR is as close to the
+//! user's code as possible.
+
+pub mod unconditional_recursion;