Start handling pattern types at the HIR -> Ty conversion boundary

compiler/rustc_hir_analysis/src/errors.rs

@@ -7,6 +7,8 @@ use rustc_errors::{
 use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
 use rustc_middle::ty::Ty;
 use rustc_span::{symbol::Ident, Span, Symbol};
+mod pattern_types;
+pub use pattern_types::*;
 
 #[derive(Diagnostic)]
 #[diag(hir_analysis_ambiguous_assoc_item)]

compiler/rustc_hir_analysis/src/errors/pattern_types.rs

@@ -0,0 +1,9 @@
+use rustc_macros::Diagnostic;
+use rustc_span::Span;
+
+#[derive(Diagnostic)]
+#[diag(hir_analysis_pattern_type_wild_pat)]
+pub struct WildPatTy {
+    #[primary_span]
+    pub span: Span,
+}

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -21,7 +21,7 @@ mod object_safety;
 
 use crate::bounds::Bounds;
 use crate::collect::HirPlaceholderCollector;
-use crate::errors::AmbiguousLifetimeBound;
+use crate::errors::{AmbiguousLifetimeBound, WildPatTy};
 use crate::hir_ty_lowering::errors::{prohibit_assoc_item_binding, GenericsArgsErrExtend};
 use crate::hir_ty_lowering::generics::{check_generic_arg_count, lower_generic_args};
 use crate::middle::resolve_bound_vars as rbv;
@@ -2195,7 +2195,15 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 // handled specially and will not descend into this routine.
                 self.ty_infer(None, hir_ty.span)
             }
-            hir::TyKind::Pat(..) => span_bug!(hir_ty.span, "{hir_ty:#?}"),
+            hir::TyKind::Pat(_ty, pat) => match pat.kind {
+                hir::PatKind::Wild => {
+                    let err = tcx.dcx().emit_err(WildPatTy { span: pat.span });
+                    Ty::new_error(tcx, err)
+                }
+                hir::PatKind::Range(_, _, _) => Ty::new_misc_error(tcx),
+                hir::PatKind::Err(e) => Ty::new_error(tcx, e),
+                _ => span_bug!(pat.span, "unsupported pattern for pattern type: {pat:#?}"),
+            },
             hir::TyKind::Err(guar) => Ty::new_error(tcx, *guar),
         };