Change lint message.

Author: xiongmao86

clippy_lints/src/methods/mod.rs

@@ -3213,18 +3213,27 @@ fn lint_filetype_is_file(cx: &LateContext<'_, '_>, expr: &hir::Expr<'_>, args: &
         return;
     }
 
+    let span: &hir::Expr<'_>;
+    let verb: &str;
+    let lint_unary: &str;
+    let help_unary: &str;
     if_chain! {
         if let Some(parent) = get_parent_expr(cx, expr);
         if let hir::ExprKind::Unary(op, _) = parent.kind;
         if op == hir::UnNot;
         then {
-            let lint_msg = "`!FileType::is_file()` does not deny all readable file types";
-            let help_msg = "use `FileType::is_dir()` instead";
-            span_help_and_lint(cx, FILETYPE_IS_FILE, parent.span, lint_msg, help_msg);
+            lint_unary = "!";
+            verb = "denys";
+            help_unary = "";
+            span = parent;
         } else {
-            let lint_msg = "`FileType::is_file()` does not cover all readable file types";
-            let help_msg = "use `!FileType::is_dir()` instead";
-            span_help_and_lint(cx, FILETYPE_IS_FILE, expr.span, lint_msg, help_msg);
+            lint_unary = "";
+            verb = "covers";
+            help_unary = "!";
+            span = expr;
         }
     }
+    let lint_msg = format!("`{}FileType::is_file()` only {} regular files", lint_unary, verb);
+    let help_msg = format!("use `{}FileType::is_dir()` instead", help_unary);
+    span_help_and_lint(cx, FILETYPE_IS_FILE, span.span, &lint_msg, &help_msg);
 }

tests/ui/filetype_is_file.stderr

@@ -1,4 +1,4 @@
-error: `FileType::is_file()` does not cover all readable file types
+error: `FileType::is_file()` only covers regular files
   --> $DIR/filetype_is_file.rs:8:8
    |
 LL |     if fs::metadata("foo.txt")?.file_type().is_file() {
@@ -7,15 +7,15 @@ LL |     if fs::metadata("foo.txt")?.file_type().is_file() {
    = note: `-D clippy::filetype-is-file` implied by `-D warnings`
    = help: use `!FileType::is_dir()` instead
 
-error: `!FileType::is_file()` does not deny all readable file types
+error: `!FileType::is_file()` only denys regular files
   --> $DIR/filetype_is_file.rs:13:8
    |
 LL |     if !fs::metadata("foo.txt")?.file_type().is_file() {
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: use `FileType::is_dir()` instead
 
-error: `FileType::is_file()` does not cover all readable file types
+error: `FileType::is_file()` only covers regular files
   --> $DIR/filetype_is_file.rs:18:9
    |
 LL |     if !fs::metadata("foo.txt")?.file_type().is_file().bitor(true) {