Don't report any errors in lower_intrinsics. They should have been typecked before.

compiler/rustc_mir_transform/messages.ftl

@@ -42,8 +42,6 @@ mir_transform_requires_unsafe = {$details} is unsafe and requires unsafe {$op_in
     }
     .not_inherited = items do not inherit unsafety from separate enclosing items
 
-mir_transform_simd_shuffle_last_const = last argument of `simd_shuffle` is required to be a `const` item
-
 mir_transform_target_feature_call_label = call to function with `#[target_feature]`
 mir_transform_target_feature_call_note = can only be called if the required target features are available
 

compiler/rustc_mir_transform/src/errors.rs

@@ -258,10 +258,3 @@ pub(crate) struct MustNotSuspendReason {
     pub span: Span,
     pub reason: String,
 }
-
-#[derive(Diagnostic)]
-#[diag(mir_transform_simd_shuffle_last_const)]
-pub(crate) struct SimdShuffleLastConst {
-    #[primary_span]
-    pub span: Span,
-}

compiler/rustc_mir_transform/src/lower_intrinsics.rs

@@ -1,11 +1,10 @@
 //! Lowers intrinsic calls
 
-use crate::{errors, MirPass};
+use crate::MirPass;
 use rustc_middle::mir::*;
 use rustc_middle::ty::GenericArgsRef;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::symbol::{sym, Symbol};
-use rustc_span::Span;
 use rustc_target::abi::{FieldIdx, VariantIdx};
 
 pub struct LowerIntrinsics;
@@ -304,9 +303,6 @@ impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
                             terminator.kind = TerminatorKind::Unreachable;
                         }
                     }
-                    sym::simd_shuffle => {
-                        validate_simd_shuffle(tcx, args, terminator.source_info.span);
-                    }
                     _ => {}
                 }
             }
@@ -325,9 +321,3 @@ fn resolve_rust_intrinsic<'tcx>(
     }
     None
 }
-
-fn validate_simd_shuffle<'tcx>(tcx: TyCtxt<'tcx>, args: &[Operand<'tcx>], span: Span) {
-    if !matches!(args[2], Operand::Constant(_)) {
-        tcx.sess.emit_err(errors::SimdShuffleLastConst { span });
-    }
-}