Sugggest using Path for comparing extensions

Signed-off-by: Tyler Weaver <[email protected]>

Author: tylerjw

clippy_lints/src/methods/case_sensitive_file_extension_comparisons.rs

@@ -1,7 +1,9 @@
-use clippy_utils::diagnostics::span_lint_and_help;
+use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::sugg::Sugg;
 use clippy_utils::ty::is_type_lang_item;
 use if_chain::if_chain;
 use rustc_ast::ast::LitKind;
+use rustc_errors::Applicability;
 use rustc_hir::{Expr, ExprKind, LangItem};
 use rustc_lint::LateContext;
 use rustc_span::{source_map::Spanned, Span};
@@ -28,13 +30,23 @@ pub(super) fn check<'tcx>(
         let recv_ty = cx.typeck_results().expr_ty(recv).peel_refs();
         if recv_ty.is_str() || is_type_lang_item(cx, recv_ty, LangItem::String);
         then {
-            span_lint_and_help(
+            span_lint_and_then(
                 cx,
                 CASE_SENSITIVE_FILE_EXTENSION_COMPARISONS,
-                call_span,
+                recv.span.to(call_span),
                 "case-sensitive file extension comparison",
-                None,
-                "consider using a case-insensitive comparison instead",
+                |diag| {
+                    diag.help("consider using a case-insensitive comparison instead");
+                    diag.span_suggestion(
+                        recv.span.to(call_span),
+                        "use std::path::Path",
+                        format!("std::path::Path::new({})
+        .extension()
+        .map_or(false, |ext| ext.eq_ignore_ascii_case(\"{}\"))", 
+                            Sugg::hir(cx, recv, ""), ext_str.strip_prefix('.').unwrap()),
+                        Applicability::MaybeIncorrect,
+                    );
+                }
             );
         }
     }

tests/ui/case_sensitive_file_extension_comparisons.stderr

@@ -1,43 +1,73 @@
 error: case-sensitive file extension comparison
-  --> $DIR/case_sensitive_file_extension_comparisons.rs:12:14
+  --> $DIR/case_sensitive_file_extension_comparisons.rs:12:5
    |
 LL |     filename.ends_with(".rs")
-   |              ^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider using a case-insensitive comparison instead
    = note: `-D clippy::case-sensitive-file-extension-comparisons` implied by `-D warnings`
+help: use std::path::Path
+   |
+LL ~     std::path::Path::new(filename)
+LL +         .extension()
+LL +         .map_or(false, |ext| ext.eq_ignore_ascii_case("rs"))
+   |
 
 error: case-sensitive file extension comparison
-  --> $DIR/case_sensitive_file_extension_comparisons.rs:17:27
+  --> $DIR/case_sensitive_file_extension_comparisons.rs:17:13
    |
 LL |     let _ = String::new().ends_with(".ext12");
-   |                           ^^^^^^^^^^^^^^^^^^^
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider using a case-insensitive comparison instead
+help: use std::path::Path
+   |
+LL ~     let _ = std::path::Path::new(String::new())
+LL +         .extension()
+LL ~         .map_or(false, |ext| ext.eq_ignore_ascii_case("ext12"));
+   |
 
 error: case-sensitive file extension comparison
-  --> $DIR/case_sensitive_file_extension_comparisons.rs:18:19
+  --> $DIR/case_sensitive_file_extension_comparisons.rs:18:13
    |
 LL |     let _ = "str".ends_with(".ext12");
-   |                   ^^^^^^^^^^^^^^^^^^^
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider using a case-insensitive comparison instead
+help: use std::path::Path
+   |
+LL ~     let _ = std::path::Path::new("str")
+LL +         .extension()
+LL ~         .map_or(false, |ext| ext.eq_ignore_ascii_case("ext12"));
+   |
 
 error: case-sensitive file extension comparison
-  --> $DIR/case_sensitive_file_extension_comparisons.rs:24:27
+  --> $DIR/case_sensitive_file_extension_comparisons.rs:24:13
    |
 LL |     let _ = String::new().ends_with(".EXT12");
-   |                           ^^^^^^^^^^^^^^^^^^^
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider using a case-insensitive comparison instead
+help: use std::path::Path
+   |
+LL ~     let _ = std::path::Path::new(String::new())
+LL +         .extension()
+LL ~         .map_or(false, |ext| ext.eq_ignore_ascii_case("EXT12"));
+   |
 
 error: case-sensitive file extension comparison
-  --> $DIR/case_sensitive_file_extension_comparisons.rs:25:19
+  --> $DIR/case_sensitive_file_extension_comparisons.rs:25:13
    |
 LL |     let _ = "str".ends_with(".EXT12");
-   |                   ^^^^^^^^^^^^^^^^^^^
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider using a case-insensitive comparison instead
+help: use std::path::Path
+   |
+LL ~     let _ = std::path::Path::new("str")
+LL +         .extension()
+LL ~         .map_or(false, |ext| ext.eq_ignore_ascii_case("EXT12"));
+   |
 
 error: aborting due to 5 previous errors