Added new lint for issue rust-lang#10655

Author: Mason Ray Hanna III

CHANGELOG.md

@@ -4814,6 +4814,7 @@ Released 2018-09-13
 [`partialeq_ne_impl`]: https://rust-lang.github.io/rust-clippy/master/index.html#partialeq_ne_impl
 [`partialeq_to_none`]: https://rust-lang.github.io/rust-clippy/master/index.html#partialeq_to_none
 [`path_buf_push_overwrite`]: https://rust-lang.github.io/rust-clippy/master/index.html#path_buf_push_overwrite
+[`path_join_correction`]: https://rust-lang.github.io/rust-clippy/master/index.html#path_join_correction
 [`pattern_type_mismatch`]: https://rust-lang.github.io/rust-clippy/master/index.html#pattern_type_mismatch
 [`permissions_set_readonly_false`]: https://rust-lang.github.io/rust-clippy/master/index.html#permissions_set_readonly_false
 [`positional_named_format_parameters`]: https://rust-lang.github.io/rust-clippy/master/index.html#positional_named_format_parameters

clippy_lints/src/declared_lints.rs

@@ -376,6 +376,7 @@ pub(crate) static LINTS: &[&crate::LintInfo] = &[
     crate::methods::OR_FUN_CALL_INFO,
     crate::methods::OR_THEN_UNWRAP_INFO,
     crate::methods::PATH_BUF_PUSH_OVERWRITE_INFO,
+    crate::methods::PATH_JOIN_CORRECTION_INFO,
     crate::methods::RANGE_ZIP_WITH_LEN_INFO,
     crate::methods::REPEAT_ONCE_INFO,
     crate::methods::RESULT_MAP_OR_INTO_OPTION_INFO,

clippy_lints/src/methods/mod.rs

@@ -1,3 +1,4 @@
+mod path_join_correction;
 mod bind_instead_of_map;
 mod bytecount;
 mod bytes_count_to_len;
@@ -3216,6 +3217,25 @@ declare_clippy_lint! {
     "calling `drain` in order to `clear` a container"
 }
 
+declare_clippy_lint! {
+    /// ### What it does
+    ///
+    /// ### Why is this bad?
+    ///
+    /// ### Example
+    /// ```rust
+    /// // example code where clippy issues a warning
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// // example code which does not raise clippy warning
+    /// ```
+    #[clippy::version = "1.70.0"]
+    pub PATH_JOIN_CORRECTION,
+    pedantic,
+    "default lint description"
+}
+
 pub struct Methods {
     avoid_breaking_exported_api: bool,
     msrv: Msrv,
@@ -3345,6 +3365,7 @@ impl_lint_pass!(Methods => [
     NEEDLESS_COLLECT,
     SUSPICIOUS_COMMAND_ARG_SPACE,
     CLEAR_WITH_DRAIN,
+    PATH_JOIN_CORRECTION,
 ]);
 
 /// Extracts a method call name, args, and `Span` of the method name.
@@ -3655,7 +3676,11 @@ impl Methods {
                     if let Some(("collect", _, _, span, _)) = method_call(recv) {
                         unnecessary_join::check(cx, expr, recv, join_arg, span);
                     }
+		    else {path_join_correction::check(cx, expr,  join_arg, span);}
                 },
+	        /*("join", [join_arg]) => {
+		    path_join_correction::check(cx, expr,  join_arg, span);
+		},*/
                 ("last", []) | ("skip", [_]) => {
                     if let Some((name2, recv2, args2, _span2, _)) = method_call(recv) {
                         if let ("cloned", []) = (name2, args2) {

clippy_lints/src/methods/path_join_correction.rs

@@ -0,0 +1,35 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use rustc_lint::{LateContext};
+use rustc_ast::ast::LitKind;
+use rustc_errors::Applicability;
+use rustc_hir::{Expr, ExprKind};
+use rustc_span::Span;
+
+use super::PATH_JOIN_CORRECTION;
+
+// TODO: Adjust the parameters as necessary
+
+pub(super) fn check<'tcx>(
+    cx: &LateContext<'tcx>,
+    expr: &'tcx Expr<'tcx>,
+    join_arg: &'tcx Expr<'tcx>,
+    span: Span,
+) {
+  let applicability = Applicability::MachineApplicable;
+  if_chain!(
+    if let ExprKind::Lit(spanned) = &join_arg.kind;
+    if let LitKind::Str(symbol, _) = spanned.node;
+    if symbol.as_str().starts_with('/');
+    then {
+      span_lint_and_sugg(
+	cx,
+	PATH_JOIN_CORRECTION,
+	span.with_hi(expr.span.hi()),
+	r#"argument in join called on path contains a starting '/'"#,
+	"try removing first '/'",
+	"join(\"your/path/here\")".to_owned(),
+	applicability
+      );
+    }
+  );
+}

tests/ui/path_join_correction.rs

@@ -0,0 +1,15 @@
+#![allow(unused)]
+#![warn(clippy::path_join_correction)]
+
+fn main() {
+  // should be linted
+  let path = std::path::Path::new("/bin");
+  path.join("/sh");
+  println!("{}", path.display());
+
+  //should not be linted
+  let path = std::path::Path::new("/bin");
+  path.join("sh");
+  println!("{}", path.display());
+  
+}

tests/ui/path_join_correction.stderr

@@ -0,0 +1,10 @@
+error: argument in join called on path contains a starting '/'
+  --> $DIR/path_join_correction.rs:7:8
+   |
+LL |   path.join("/sh");
+   |        ^^^^^^^^^^^ help: try removing first '/': `join("your/path/here")`
+   |
+   = note: `-D clippy::path-join-correction` implied by `-D warnings`
+
+error: aborting due to previous error
+