Don't lint range syntax with var name start and end

Author: ordovicia

clippy_lints/src/redundant_field_names.rs

@@ -1,6 +1,8 @@
+use syntax::ast::Name;
 use rustc::lint::*;
 use rustc::hir::*;
-use utils::{span_lint_and_sugg, match_var};
+use utils::{match_qpath, match_var, span_lint_and_sugg};
+use utils::paths;
 
 /// **What it does:** Checks for fields in struct literals where shorthands
 /// could be used.
@@ -36,10 +38,14 @@ impl LintPass for RedundantFieldNames {
 
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for RedundantFieldNames {
     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
-        if let ExprStruct(_, ref fields, _) = expr.node {
+        if let ExprStruct(ref path, ref fields, _) = expr.node {
             for field in fields {
                 let name = field.name.node;
 
+                if is_range_struct_field(path, &name) {
+                    continue;
+                }
+
                 if match_var(&field.expr, name) && !field.is_shorthand {
                     span_lint_and_sugg (
                         cx,
@@ -54,3 +60,27 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for RedundantFieldNames {
         }
     }
 }
+
+/// ```rust
+/// let start = 0;
+/// let _ = start..;
+///
+/// let end = 0;
+/// let _ = ..end;
+///
+/// let _ = start..end;
+/// ```
+fn is_range_struct_field(path: &QPath, name: &Name) -> bool {
+    match name.as_str().as_ref() {
+        "start" => {
+            match_qpath(path, &paths::RANGE_STD) || match_qpath(path, &paths::RANGE_FROM_STD)
+                || match_qpath(path, &paths::RANGE_INCLUSIVE_STD)
+        },
+        "end" => {
+            match_qpath(path, &paths::RANGE_STD) || match_qpath(path, &paths::RANGE_TO_STD)
+                || match_qpath(path, &paths::RANGE_INCLUSIVE_STD)
+                || match_qpath(path, &paths::RANGE_TO_INCLUSIVE_STD)
+        },
+        _ => false,
+    }
+}

tests/ui/redundant_field_names.rs

@@ -1,5 +1,6 @@
 #![warn(redundant_field_names)]
 #![allow(unused_variables)]
+#![feature(inclusive_range,inclusive_range_syntax)]
 
 mod foo {
     pub const BAR: u8 = 0;
@@ -27,4 +28,21 @@ fn main() {
         buzz: fizz, //should be ok
         foo: foo::BAR, //should be ok
     };
+
+    // Range syntax
+    let (start, end) = (0, 0);
+
+    let _ = start..;
+    let _ = ..end;
+    let _ = start..end;
+
+    let _ = ..=end;
+    let _ = start..=end;
+
+    // TODO: the followings shoule be linted
+    let _ = ::std::ops::RangeFrom { start: start };
+    let _ = ::std::ops::RangeTo { end: end };
+    let _ = ::std::ops::Range { start: start, end: end };
+    let _ = ::std::ops::RangeInclusive { start: start, end: end };
+    let _ = ::std::ops::RangeToInclusive { end: end };
 }

tests/ui/redundant_field_names.stderr

@@ -1,15 +1,15 @@
 error: redundant field names in struct initialization
-  --> $DIR/redundant_field_names.rs:23:9
+  --> $DIR/redundant_field_names.rs:24:9
    |
-23 |         gender: gender,
+24 |         gender: gender,
    |         ^^^^^^^^^^^^^^ help: replace it with: `gender`
    |
    = note: `-D redundant-field-names` implied by `-D warnings`
 
 error: redundant field names in struct initialization
-  --> $DIR/redundant_field_names.rs:24:9
+  --> $DIR/redundant_field_names.rs:25:9
    |
-24 |         age: age,
+25 |         age: age,
    |         ^^^^^^^^ help: replace it with: `age`
 
 error: aborting due to 2 previous errors