Update upstream source from tag 'upstream/1.52.1+dfsg1'

[rustc.git] / src / tools / clippy / clippy_lints / src / methods / filetype_is_file.rs

diff --git a/src/tools/clippy/clippy_lints/src/methods/filetype_is_file.rs b/src/tools/clippy/clippy_lints/src/methods/filetype_is_file.rs
new file mode 100644 (file)
index 0000000..b03835f
--- /dev/null
+++ b/src/tools/clippy/clippy_lints/src/methods/filetype_is_file.rs
@@ -0,0 +1,39 @@
+use crate::utils::{get_parent_expr, match_type, paths, span_lint_and_help};
+use if_chain::if_chain;
+use rustc_hir as hir;
+use rustc_lint::LateContext;
+use rustc_span::source_map::Span;
+
+use super::FILETYPE_IS_FILE;
+
+pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, args: &[hir::Expr<'_>]) {
+    let ty = cx.typeck_results().expr_ty(&args[0]);
+
+    if !match_type(cx, ty, &paths::FILE_TYPE) {
+        return;
+    }
+
+    let span: Span;
+    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::UnOp::Not;
+        then {
+            lint_unary = "!";
+            verb = "denies";
+            help_unary = "";
+            span = parent.span;
+        } else {
+            lint_unary = "";
+            verb = "covers";
+            help_unary = "!";
+            span = expr.span;
+        }
+    }
+    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_lint_and_help(cx, FILETYPE_IS_FILE, span, &lint_msg, None, &help_msg);
+}