Fix create_dir ignores paths in suggestions (#15011)

Closes rust-lang/rust-clippy#14994

changelog: [`create_dir`] fix missing paths in suggestions

Author: Alexendoo

clippy_lints/src/create_dir.rs

@@ -1,7 +1,6 @@
 use clippy_utils::diagnostics::span_lint_and_then;
-use clippy_utils::source::snippet_with_applicability;
 use rustc_errors::Applicability;
-use rustc_hir::{Expr, ExprKind};
+use rustc_hir::{Expr, ExprKind, QPath};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
 use rustc_span::sym;
@@ -34,26 +33,28 @@ declare_lint_pass!(CreateDir => [CREATE_DIR]);
 
 impl LateLintPass<'_> for CreateDir {
     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
-        if let ExprKind::Call(func, [arg]) = expr.kind
+        if let ExprKind::Call(func, [_]) = expr.kind
             && let ExprKind::Path(ref path) = func.kind
             && let Some(def_id) = cx.qpath_res(path, func.hir_id).opt_def_id()
             && cx.tcx.is_diagnostic_item(sym::fs_create_dir, def_id)
+            && let QPath::Resolved(_, path) = path
+            && let Some(last) = path.segments.last()
         {
             span_lint_and_then(
                 cx,
                 CREATE_DIR,
                 expr.span,
                 "calling `std::fs::create_dir` where there may be a better way",
                 |diag| {
-                    let mut app = Applicability::MaybeIncorrect;
-                    diag.span_suggestion_verbose(
-                        expr.span,
+                    let mut suggestions = vec![(last.ident.span.shrink_to_hi(), "_all".to_owned())];
+                    if path.segments.len() == 1 {
+                        suggestions.push((path.span.shrink_to_lo(), "std::fs::".to_owned()));
+                    }
+
+                    diag.multipart_suggestion_verbose(
                         "consider calling `std::fs::create_dir_all` instead",
-                        format!(
-                            "create_dir_all({})",
-                            snippet_with_applicability(cx, arg.span, "..", &mut app)
-                        ),
-                        app,
+                        suggestions,
+                        Applicability::MaybeIncorrect,
                     );
                 },
             );

tests/ui/create_dir.fixed

@@ -7,12 +7,31 @@ fn create_dir() {}
 
 fn main() {
     // Should be warned
-    create_dir_all("foo");
+    std::fs::create_dir_all("foo");
     //~^ create_dir
-    create_dir_all("bar").unwrap();
+    std::fs::create_dir_all("bar").unwrap();
     //~^ create_dir
 
     // Shouldn't be warned
     create_dir();
     std::fs::create_dir_all("foobar");
 }
+
+mod issue14994 {
+    fn with_no_prefix() {
+        use std::fs::create_dir;
+        std::fs::create_dir_all("some/dir").unwrap();
+        //~^ create_dir
+    }
+
+    fn with_fs_prefix() {
+        use std::fs;
+        fs::create_dir_all("/some/dir").unwrap();
+        //~^ create_dir
+    }
+
+    fn with_full_prefix() {
+        std::fs::create_dir_all("/some/dir").unwrap();
+        //~^ create_dir
+    }
+}

tests/ui/create_dir.rs

@@ -16,3 +16,22 @@ fn main() {
     create_dir();
     std::fs::create_dir_all("foobar");
 }
+
+mod issue14994 {
+    fn with_no_prefix() {
+        use std::fs::create_dir;
+        create_dir("some/dir").unwrap();
+        //~^ create_dir
+    }
+
+    fn with_fs_prefix() {
+        use std::fs;
+        fs::create_dir("/some/dir").unwrap();
+        //~^ create_dir
+    }
+
+    fn with_full_prefix() {
+        std::fs::create_dir("/some/dir").unwrap();
+        //~^ create_dir
+    }
+}

tests/ui/create_dir.stderr

@@ -8,9 +8,8 @@ LL |     std::fs::create_dir("foo");
    = help: to override `-D warnings` add `#[allow(clippy::create_dir)]`
 help: consider calling `std::fs::create_dir_all` instead
    |
-LL -     std::fs::create_dir("foo");
-LL +     create_dir_all("foo");
-   |
+LL |     std::fs::create_dir_all("foo");
+   |                        ++++
 
 error: calling `std::fs::create_dir` where there may be a better way
   --> tests/ui/create_dir.rs:12:5
@@ -20,9 +19,41 @@ LL |     std::fs::create_dir("bar").unwrap();
    |
 help: consider calling `std::fs::create_dir_all` instead
    |
-LL -     std::fs::create_dir("bar").unwrap();
-LL +     create_dir_all("bar").unwrap();
+LL |     std::fs::create_dir_all("bar").unwrap();
+   |                        ++++
+
+error: calling `std::fs::create_dir` where there may be a better way
+  --> tests/ui/create_dir.rs:23:9
+   |
+LL |         create_dir("some/dir").unwrap();
+   |         ^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: consider calling `std::fs::create_dir_all` instead
+   |
+LL |         std::fs::create_dir_all("some/dir").unwrap();
+   |         +++++++++          ++++
+
+error: calling `std::fs::create_dir` where there may be a better way
+  --> tests/ui/create_dir.rs:29:9
+   |
+LL |         fs::create_dir("/some/dir").unwrap();
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: consider calling `std::fs::create_dir_all` instead
+   |
+LL |         fs::create_dir_all("/some/dir").unwrap();
+   |                       ++++
+
+error: calling `std::fs::create_dir` where there may be a better way
+  --> tests/ui/create_dir.rs:34:9
+   |
+LL |         std::fs::create_dir("/some/dir").unwrap();
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: consider calling `std::fs::create_dir_all` instead
    |
+LL |         std::fs::create_dir_all("/some/dir").unwrap();
+   |                            ++++
 
-error: aborting due to 2 previous errors
+error: aborting due to 5 previous errors