Auto merge of rust-lang#12429 - Alexendoo:redundant-field-names-macro-ctxt, r=Manishearth

Don't lint `redundant_field_names` across macro boundaries

Fixes rust-lang#12426

The `field.span.eq_ctxt(field.ident.span)` addition is the relevant line for the bugfix

The current implementation checks that the field's name and the path are in the same context by comparing the idents, but not that the two are in the same context as the entire field itself, so in local macros `SomeStruct { $ident: $ident }` would get linted

changelog: none

Author: bors

clippy_lints/src/redundant_field_names.rs

@@ -59,24 +59,22 @@ impl EarlyLintPass for RedundantFieldNames {
         }
         if let ExprKind::Struct(ref se) = expr.kind {
             for field in &se.fields {
-                if field.is_shorthand {
-                    continue;
-                }
-                if let ExprKind::Path(None, path) = &field.expr.kind {
-                    if path.segments.len() == 1
-                        && path.segments[0].ident == field.ident
-                        && path.segments[0].args.is_none()
-                    {
-                        span_lint_and_sugg(
-                            cx,
-                            REDUNDANT_FIELD_NAMES,
-                            field.span,
-                            "redundant field names in struct initialization",
-                            "replace it with",
-                            field.ident.to_string(),
-                            Applicability::MachineApplicable,
-                        );
-                    }
+                if !field.is_shorthand
+                    && let ExprKind::Path(None, path) = &field.expr.kind
+                    && let [segment] = path.segments.as_slice()
+                    && segment.args.is_none()
+                    && segment.ident == field.ident
+                    && field.span.eq_ctxt(field.ident.span)
+                {
+                    span_lint_and_sugg(
+                        cx,
+                        REDUNDANT_FIELD_NAMES,
+                        field.span,
+                        "redundant field names in struct initialization",
+                        "replace it with",
+                        field.ident.to_string(),
+                        Applicability::MachineApplicable,
+                    );
                 }
             }
         }

tests/ui/redundant_field_names.fixed

@@ -20,7 +20,7 @@ struct Person {
 }
 
 pub struct S {
-    v: String,
+    v: usize,
 }
 
 fn main() {
@@ -59,11 +59,22 @@ fn main() {
     let _ = RangeToInclusive { end };
 
     external! {
-        let v = String::new();
+        let v = 1;
         let _ = S {
             v: v
         };
     }
+
+    let v = 2;
+    macro_rules! internal {
+        ($i:ident) => {
+            let _ = S { v };
+            let _ = S { $i: v };
+            let _ = S { v: $i };
+            let _ = S { $i: $i };
+        };
+    }
+    internal!(v);
 }
 
 fn issue_3476() {

tests/ui/redundant_field_names.rs

@@ -20,7 +20,7 @@ struct Person {
 }
 
 pub struct S {
-    v: String,
+    v: usize,
 }
 
 fn main() {
@@ -59,11 +59,22 @@ fn main() {
     let _ = RangeToInclusive { end: end };
 
     external! {
-        let v = String::new();
+        let v = 1;
         let _ = S {
             v: v
         };
     }
+
+    let v = 2;
+    macro_rules! internal {
+        ($i:ident) => {
+            let _ = S { v: v };
+            let _ = S { $i: v };
+            let _ = S { v: $i };
+            let _ = S { $i: $i };
+        };
+    }
+    internal!(v);
 }
 
 fn issue_3476() {

tests/ui/redundant_field_names.stderr

@@ -44,10 +44,21 @@ LL |     let _ = RangeToInclusive { end: end };
    |                                ^^^^^^^^ help: replace it with: `end`
 
 error: redundant field names in struct initialization
-  --> tests/ui/redundant_field_names.rs:88:25
+  --> tests/ui/redundant_field_names.rs:71:25
+   |
+LL |             let _ = S { v: v };
+   |                         ^^^^ help: replace it with: `v`
+...
+LL |     internal!(v);
+   |     ------------ in this macro invocation
+   |
+   = note: this error originates in the macro `internal` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: redundant field names in struct initialization
+  --> tests/ui/redundant_field_names.rs:99:25
    |
 LL |     let _ = RangeFrom { start: start };
    |                         ^^^^^^^^^^^^ help: replace it with: `start`
 
-error: aborting due to 8 previous errors
+error: aborting due to 9 previous errors