Maintain a list of types permitted per pattern

compiler/rustc_hir_analysis/messages.ftl

@@ -234,6 +234,9 @@ hir_analysis_inherent_ty_outside_relevant = cannot define inherent `impl` for a
     .help = consider moving this inherent impl into the crate defining the type if possible
     .span_help = alternatively add `#[rustc_allow_incoherent_impl]` to the relevant impl items
 
+hir_analysis_invalid_base_type = `{$ty}` is not a valid base type for range patterns
+    .note = range patterns only support integers
+
 hir_analysis_invalid_generic_receiver_ty = invalid generic `self` parameter type: `{$receiver_ty}`
     .note = type of `self` must not be a method generic parameter type
 
@@ -438,7 +441,6 @@ hir_analysis_pattern_type_wild_pat = wildcard patterns are not permitted for pat
     .label = this type is the same as the inner type without a pattern
 hir_analysis_placeholder_not_allowed_item_signatures = the placeholder `_` is not allowed within types on item signatures for {$kind}
     .label = not allowed in type signatures
-
 hir_analysis_precise_capture_self_alias = `Self` can't be captured in `use<...>` precise captures list, since it is an alias
     .label = `Self` is not a generic argument, but an alias to the type of the {$what}
 

compiler/rustc_hir_analysis/src/errors/pattern_types.rs

@@ -1,4 +1,5 @@
 use rustc_macros::Diagnostic;
+use rustc_middle::ty::Ty;
 use rustc_span::Span;
 
 #[derive(Diagnostic)]
@@ -7,3 +8,14 @@ pub(crate) struct WildPatTy {
     #[primary_span]
     pub span: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag(hir_analysis_invalid_base_type)]
+pub(crate) struct InvalidBaseType<'tcx> {
+    pub ty: Ty<'tcx>,
+    #[primary_span]
+    pub ty_span: Span,
+    pub pat: &'static str,
+    #[note]
+    pub pat_span: Span,
+}

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -53,7 +53,7 @@ use tracing::{debug, instrument};
 
 use crate::bounds::Bounds;
 use crate::check::check_abi_fn_ptr;
-use crate::errors::{AmbiguousLifetimeBound, BadReturnTypeNotation, WildPatTy};
+use crate::errors::{AmbiguousLifetimeBound, BadReturnTypeNotation, InvalidBaseType, WildPatTy};
 use crate::hir_ty_lowering::errors::{GenericsArgsErrExtend, prohibit_assoc_item_constraint};
 use crate::hir_ty_lowering::generics::{check_generic_arg_count, lower_generic_args};
 use crate::middle::resolve_bound_vars as rbv;
@@ -2432,6 +2432,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 self.ty_infer(None, hir_ty.span)
             }
             hir::TyKind::Pat(ty, pat) => {
+                let ty_span = ty.span;
                 let ty = self.lower_ty(ty);
                 let pat_ty = match pat.kind {
                     hir::PatKind::Wild => {
@@ -2439,6 +2440,18 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                         Ty::new_error(tcx, err)
                     }
                     hir::PatKind::Range(start, end, include_end) => {
+                        let ty = match ty.kind() {
+                            ty::Int(_) | ty::Uint(_) | ty::Char => ty,
+                            _ => Ty::new_error(
+                                tcx,
+                                self.dcx().emit_err(InvalidBaseType {
+                                    ty,
+                                    pat: "range",
+                                    ty_span,
+                                    pat_span: pat.span,
+                                }),
+                            ),
+                        };
                         let expr_to_const = |expr: &'tcx hir::PatExpr<'tcx>| -> ty::Const<'tcx> {
                             let (c, c_ty) = match expr.kind {
                                 hir::PatExprKind::Lit { lit, negated } => {