Remove constraints argument from path_all

It was never used

src/libsyntax_ext/deriving/clone.rs

@@ -115,7 +115,7 @@ fn cs_clone_shallow(name: &str,
         let span = cx.with_def_site_ctxt(span);
         let assert_path = cx.path_all(span, true,
                                         cx.std_path(&[sym::clone, Symbol::intern(helper_name)]),
-                                        vec![GenericArg::Type(ty)], vec![]);
+                                        vec![GenericArg::Type(ty)]);
         stmts.push(cx.stmt_let_type_only(span, cx.ty_path(assert_path)));
     }
     fn process_variant(cx: &mut ExtCtxt<'_>, stmts: &mut Vec<ast::Stmt>, variant: &VariantData) {

src/libsyntax_ext/deriving/cmp/eq.rs

@@ -56,7 +56,7 @@ fn cs_total_eq_assert(cx: &mut ExtCtxt<'_>,
         let span = cx.with_def_site_ctxt(span);
         let assert_path = cx.path_all(span, true,
                                         cx.std_path(&[sym::cmp, Symbol::intern(helper_name)]),
-                                        vec![GenericArg::Type(ty)], vec![]);
+                                        vec![GenericArg::Type(ty)]);
         stmts.push(cx.stmt_let_type_only(span, cx.ty_path(assert_path)));
     }
     fn process_variant(cx: &mut ExtCtxt<'_>,

src/libsyntax_ext/deriving/generic/mod.rs

@@ -664,7 +664,7 @@ impl<'a> TraitDef<'a> {
         }).collect();
 
         // Create the type of `self`.
-        let path = cx.path_all(self.span, false, vec![type_ident], self_params, vec![]);
+        let path = cx.path_all(self.span, false, vec![type_ident], self_params);
         let self_type = cx.ty_path(path);
 
         let attr = cx.attribute(cx.meta_word(self.span, sym::automatically_derived));

src/libsyntax_ext/deriving/generic/ty.rs

@@ -82,12 +82,12 @@ impl<'a> Path<'a> {
                        .collect();
 
         match self.kind {
-            PathKind::Global => cx.path_all(span, true, idents, params, Vec::new()),
-            PathKind::Local => cx.path_all(span, false, idents, params, Vec::new()),
+            PathKind::Global => cx.path_all(span, true, idents, params),
+            PathKind::Local => cx.path_all(span, false, idents, params),
             PathKind::Std => {
                 let def_site = cx.with_def_site_ctxt(DUMMY_SP);
                 idents.insert(0, Ident::new(kw::DollarCrate, def_site));
-                cx.path_all(span, false, idents, params, Vec::new())
+                cx.path_all(span, false, idents, params)
             }
         }
 
@@ -183,7 +183,7 @@ impl<'a> Ty<'a> {
                     }
                 }).collect();
 
-                cx.path_all(span, false, vec![self_ty], params, vec![])
+                cx.path_all(span, false, vec![self_ty], params)
             }
             Literal(ref p) => p.to_path(cx, span, self_ty, generics),
             Ptr(..) => cx.span_bug(span, "pointer in a path in generic `derive`"),

src/libsyntax_ext/env.rs

@@ -32,7 +32,7 @@ pub fn expand_option_env<'cx>(cx: &'cx mut ExtCtxt<'_>,
                                                                  Ident::new(sym::str, sp)),
                                                      Some(lt),
                                                      ast::Mutability::Immutable))],
-                                     vec![]))
+                                     ))
         }
         Ok(s) => {
             cx.expr_call_global(sp,