move walk_ty() to utils module and rename to walk_ptrs_ty

src/len_zero.rs

@@ -9,8 +9,7 @@ use rustc::middle::ty::{self, TypeVariants, TypeAndMut, MethodTraitItemId, ImplO
 use rustc::middle::def::{DefTy, DefStruct, DefTrait};
 use syntax::codemap::{Span, Spanned};
 use syntax::ast::*;
-use misc::walk_ty;
-use utils::span_lint;
+use utils::{span_lint, walk_ptrs_ty};
 
 declare_lint!(pub LEN_ZERO, Warn,
               "Warn when .is_empty() could be used instead of checking .len()");
@@ -136,7 +135,7 @@ fn has_is_empty(cx: &Context, expr: &Expr) -> bool {
                 |iids| iids.iter().any(|i| is_is_empty(cx, i)))))
     }
 
-    let ty = &walk_ty(&cx.tcx.expr_ty(expr));
+    let ty = &walk_ptrs_ty(&cx.tcx.expr_ty(expr));
     match ty.sty {
         ty::TyTrait(_) => cx.tcx.trait_item_def_ids.borrow().get(
             &ty.ty_to_def_id().expect("trait impl not found")).map_or(false,

src/misc.rs

@@ -7,14 +7,7 @@ use rustc::lint::{Context, LintPass, LintArray, Lint, Level};
 use rustc::middle::ty;
 use syntax::codemap::{Span, Spanned};
 
-use utils::{match_path, snippet, span_lint, span_help_and_lint};
-
-pub fn walk_ty<'t>(ty: ty::Ty<'t>) -> ty::Ty<'t> {
-    match ty.sty {
-        ty::TyRef(_, ref tm) | ty::TyRawPtr(ref tm) => walk_ty(tm.ty),
-        _ => ty
-    }
-}
+use utils::{match_path, snippet, span_lint, span_help_and_lint, walk_ptrs_ty};
 
 /// Handles uncategorized lints
 /// Currently handles linting of if-let-able matches
@@ -87,7 +80,7 @@ impl LintPass for StrToStringPass {
         }
 
         fn is_str(cx: &Context, expr: &ast::Expr) -> bool {
-            match walk_ty(cx.tcx.expr_ty(expr)).sty {
+            match walk_ptrs_ty(cx.tcx.expr_ty(expr)).sty {
                 ty::TyStr => true,
                 _ => false
             }
@@ -175,7 +168,7 @@ impl LintPass for FloatCmp {
 }
 
 fn is_float(cx: &Context, expr: &Expr) -> bool {
-    if let ty::TyFloat(_) = walk_ty(cx.tcx.expr_ty(expr)).sty {
+    if let ty::TyFloat(_) = walk_ptrs_ty(cx.tcx.expr_ty(expr)).sty {
         true
     } else {
         false
@@ -274,7 +267,7 @@ fn check_to_owned(cx: &Context, expr: &Expr, other_span: Span) {
 
 fn is_str_arg(cx: &Context, args: &[P<Expr>]) -> bool {
     args.len() == 1 && if let ty::TyStr =
-        walk_ty(cx.tcx.expr_ty(&*args[0])).sty { true } else { false }
+        walk_ptrs_ty(cx.tcx.expr_ty(&*args[0])).sty { true } else { false }
 }
 
 declare_lint!(pub NEEDLESS_RETURN, Warn,

src/strings.rs

@@ -8,9 +8,8 @@ use rustc::middle::ty::TypeVariants::TyStruct;
 use syntax::ast::*;
 use syntax::codemap::{Span, Spanned};
 use eq_op::is_exp_equal;
-use misc::walk_ty;
 use types::match_ty_unwrap;
-use utils::{match_def_path, span_lint};
+use utils::{match_def_path, span_lint, walk_ptrs_ty};
 
 declare_lint! {
     pub STRING_ADD_ASSIGN,
@@ -38,7 +37,7 @@ impl LintPass for StringAdd {
 }
 
 fn is_string(cx: &Context, e: &Expr) -> bool {
-    if let TyStruct(did, _) = walk_ty(cx.tcx.expr_ty(e)).sty {
+    if let TyStruct(did, _) = walk_ptrs_ty(cx.tcx.expr_ty(e)).sty {
         match_def_path(cx, did.did, &["std", "string", "String"])
     } else { false }
 }

src/utils.rs

@@ -84,3 +84,11 @@ pub fn span_help_and_lint(cx: &Context, lint: &'static Lint, span: Span,
         cx.sess().fileline_help(span, help);
     }
 }
+
+/// return the base type for references and raw pointers
+pub fn walk_ptrs_ty<'t>(ty: ty::Ty<'t>) -> ty::Ty<'t> {
+    match ty.sty {
+        ty::TyRef(_, ref tm) | ty::TyRawPtr(ref tm) => walk_ptrs_ty(tm.ty),
+        _ => ty
+    }
+}