From 5342a26fd014ef95a0f72f5016682b8a05254e95 Mon Sep 17 00:00:00 2001
From: Richard Dodd <richard.o.dodd@gmail.com>
Date: Tue, 21 Aug 2018 13:11:53 +0100
Subject: [PATCH] Clean up checking code a bit

---
 crates/macro-support/src/parser.rs | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/crates/macro-support/src/parser.rs b/crates/macro-support/src/parser.rs
index 9dd61eba..5fc0c05f 100644
--- a/crates/macro-support/src/parser.rs
+++ b/crates/macro-support/src/parser.rs
@@ -1115,18 +1115,14 @@ fn assert_last_param_is_slice(decl: &syn::FnDecl) -> Result<(), Diagnostic> {
     }
 
     let arg = decl.inputs.last().ok_or_else(|| not_slice_error(&decl.inputs))?;
-    let ty = match arg.value() {
-        syn::FnArg::Captured(ref arg_cap) => &arg_cap.ty,
-        _ => return Err(not_slice_error(&arg))
-    };
-    match ty {
-        syn::Type::Reference(ref ref_ty) => match &*ref_ty.elem {
-            syn::Type::Slice(_) => Ok(()),
-            _ => Err(not_slice_error(ty))
-        },
-        _ => Err(not_slice_error(ty))
+    if let syn::FnArg::Captured(ref arg_cap) = arg.value() {
+        if let syn::Type::Reference(ref ref_ty) = arg_cap.ty {
+            if let syn::Type::Slice(_) = *ref_ty.elem {
+                return Ok(())
+            }
+        }
     }
-
+    Err(not_slice_error(&arg))
 }
 
 /// If the path is a single ident, return it.