Merge pull request #3010 from mikerite/issue2971

Fix #2971

Author: oli-obk

clippy_lints/src/identity_conversion.rs

@@ -85,7 +85,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for IdentityConversion {
                         let a = cx.tables.expr_ty(e);
                         let b = cx.tables.expr_ty(&args[0]);
                         if same_tys(cx, a, b) {
-                            let sugg = snippet(cx, args[0].span, "<expr>").into_owned();
+                            let sugg = snippet(cx, args[0].span.source_callsite(), "<expr>").into_owned();
                             let sugg_msg = format!("consider removing `{}()`", snippet(cx, path.span, "From::from"));
                             span_lint_and_then(cx, IDENTITY_CONVERSION, e.span, "identical conversion", |db| {
                                 db.span_suggestion(e.span, &sugg_msg, sugg);

tests/ui/identity_conversion.rs

@@ -38,6 +38,7 @@ fn main() {
     let _: String = "foo".to_string().into();
     let _: String = From::from("foo".to_string());
     let _ = String::from("foo".to_string());
+    let _ = String::from(format!("A: {:04}", 123));
     let _ = "".lines().into_iter();
     let _ = vec![1, 2, 3].into_iter().into_iter();
 }

tests/ui/identity_conversion.stderr

@@ -43,14 +43,20 @@ error: identical conversion
 error: identical conversion
   --> $DIR/identity_conversion.rs:41:13
    |
-41 |     let _ = "".lines().into_iter();
-   |             ^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `.into_iter()`: `"".lines()`
+41 |     let _ = String::from(format!("A: {:04}", 123));
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `String::from()`: `format!("A: {:04}", 123)`
 
 error: identical conversion
   --> $DIR/identity_conversion.rs:42:13
    |
-42 |     let _ = vec![1, 2, 3].into_iter().into_iter();
+42 |     let _ = "".lines().into_iter();
+   |             ^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `.into_iter()`: `"".lines()`
+
+error: identical conversion
+  --> $DIR/identity_conversion.rs:43:13
+   |
+43 |     let _ = vec![1, 2, 3].into_iter().into_iter();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `.into_iter()`: `vec![1, 2, 3].into_iter()`
 
-error: aborting due to 8 previous errors
+error: aborting due to 9 previous errors