Include const generic type bounds in their spans

Closes rust-lang#4310

Author: ayazhafiz

Diff for: src/formatting/items.rs

@@ -2263,11 +2263,10 @@ fn rewrite_fn_base(
 
     // Skip `pub(crate)`.
     let lo_after_visibility = get_bytepos_after_visibility(&fn_sig.visibility, span);
-    // A conservative estimation, to goal is to be over all parens in generics
+    // A conservative estimation, the goal is to be over all parens in generics
     let params_start = fn_sig
         .generics
         .params
-        .iter()
         .last()
         .map_or(lo_after_visibility, |param| param.span().hi());
     let params_end = if fd.inputs.is_empty() {

Diff for: src/formatting/spanned.rs

@@ -131,7 +131,8 @@ impl Spanned for ast::GenericParam {
         };
         let ty_hi = if let ast::GenericParamKind::Type {
             default: Some(ref ty),
-        } = self.kind
+        }
+        | ast::GenericParamKind::Const { ref ty, .. } = self.kind
         {
             ty.span().hi()
         } else {

Diff for: tests/target/issue-4310.rs

@@ -0,0 +1,9 @@
+#![feature(const_generics)]
+
+fn foo<
+    const N: [u8; {
+        struct Inner<'a>(&'a ());
+        3
+    }],
+>() {
+}