changelog: new lint: [split_with_space]

CHANGELOG.md

@@ -5826,6 +5826,7 @@ Released 2018-09-13
 [`size_of_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#size_of_ref
 [`skip_while_next`]: https://rust-lang.github.io/rust-clippy/master/index.html#skip_while_next
 [`slow_vector_initialization`]: https://rust-lang.github.io/rust-clippy/master/index.html#slow_vector_initialization
+[`split_with_space`]: https://rust-lang.github.io/rust-clippy/master/index.html#split_with_space
 [`stable_sort_primitive`]: https://rust-lang.github.io/rust-clippy/master/index.html#stable_sort_primitive
 [`std_instead_of_alloc`]: https://rust-lang.github.io/rust-clippy/master/index.html#std_instead_of_alloc
 [`std_instead_of_core`]: https://rust-lang.github.io/rust-clippy/master/index.html#std_instead_of_core

clippy_lints/src/declared_lints.rs

@@ -665,6 +665,7 @@ pub(crate) static LINTS: &[&crate::LintInfo] = &[
     crate::std_instead_of_core::STD_INSTEAD_OF_CORE_INFO,
     crate::string_patterns::MANUAL_PATTERN_CHAR_COMPARISON_INFO,
     crate::string_patterns::SINGLE_CHAR_PATTERN_INFO,
+    crate::strings::SPLIT_WITH_SPACE_INFO,
     crate::strings::STRING_ADD_INFO,
     crate::strings::STRING_ADD_ASSIGN_INFO,
     crate::strings::STRING_FROM_UTF8_AS_BYTES_INFO,

clippy_lints/src/lib.rs

@@ -1016,6 +1016,7 @@ pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {
     store.register_early_pass(|| Box::new(pub_use::PubUse));
     store.register_late_pass(|_| Box::new(format_push_string::FormatPushString));
     store.register_late_pass(move |_| Box::new(large_include_file::LargeIncludeFile::new(max_include_file_size)));
+    store.register_late_pass(|_| Box::new(strings::SplitWithSpace));
     store.register_late_pass(|_| Box::new(strings::TrimSplitWhitespace));
     store.register_late_pass(|_| Box::new(rc_clone_in_vec_init::RcCloneInVecInit));
     store.register_early_pass(|| Box::<duplicate_mod::DuplicateMod>::default());

clippy_lints/src/strings.rs

@@ -5,6 +5,7 @@ use clippy_utils::{
     get_expr_use_or_unification_node, get_parent_expr, is_lint_allowed, is_path_diagnostic_item, method_calls,
     peel_blocks, SpanlessEq,
 };
+use rustc_ast::ast::LitKind;
 use rustc_errors::Applicability;
 use rustc_hir::def_id::DefId;
 use rustc_hir::{BinOpKind, BorrowKind, Expr, ExprKind, LangItem, Node, QPath};
@@ -467,6 +468,49 @@ impl<'tcx> LateLintPass<'tcx> for StringToString {
     }
 }
 
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for calling `str::split` with the ASCII space character instead of `str::split_whitespace`.
+    ///
+    /// ### Why is this bad?
+    /// `split` using the ASCII space character does not handle cases where there is a different space character used. `split_whitespace` handles all whitespace characters.
+    ///
+    /// ### Example
+    /// ```no_run
+    /// "A B C".split(' ');
+    /// ```
+    /// Use instead:
+    /// ```no_run
+    /// "A B C".split_whitespace();
+    /// ```
+    #[clippy::version = "1.81.0"]
+    pub SPLIT_WITH_SPACE,
+    pedantic,
+    "using `str::split` with the ASCII space character instead of `str::split_whitespace`"
+}
+declare_lint_pass!(SplitWithSpace => [SPLIT_WITH_SPACE]);
+
+impl<'tcx> LateLintPass<'tcx> for SplitWithSpace {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &Expr<'_>) {
+        if let ExprKind::MethodCall(path, _split_recv, [arg], split_ws_span) = expr.kind
+            && path.ident.name == sym!(split)
+            && let ExprKind::Lit(lit) = arg.kind
+            && (matches!(lit.node, LitKind::Char(' '))
+                || matches!(lit.node, LitKind::Str(str, _) if str.as_str() == " "))
+        {
+            span_lint_and_sugg(
+                cx,
+                SPLIT_WITH_SPACE,
+                split_ws_span.with_hi(split_ws_span.lo()),
+                "found call to `str::split` that uses the ASCII space character as an argument".to_string(),
+                "replace the use of `str::split` with `str::split_whitespace`".to_string(),
+                String::new(),
+                Applicability::MachineApplicable,
+            );
+        }
+    }
+}
+
 declare_clippy_lint! {
     /// ### What it does
     /// Warns about calling `str::trim` (or variants) before `str::split_whitespace`.

tests/ui/split_with_space.rs

@@ -0,0 +1,16 @@
+//@aux-build:proc_macros.rs
+//@no-rustfix
+
+#[deny(clippy::split_with_space)]
+#[allow(unused)]
+fn main() {
+    let some_space_delimtetered_string = "Hello everyone! How are you doing?";
+
+    for substr in some_space_delimtetered_string.split(' ') {
+        println!("{substr}");
+    }
+
+    for substr in some_space_delimtetered_string.split(" ") {
+        println!("{substr}");
+    }
+}

tests/ui/split_with_space.stderr

@@ -0,0 +1,20 @@
+error: found call to `str::split` that uses the ASCII space character as an argument
+  --> tests/ui/split_with_space.rs:9:50
+   |
+LL |     for substr in some_space_delimtetered_string.split(' ') {
+   |                                                  ^ help: replace the use of `str::split` with `str::split_whitespace`
+   |
+note: the lint level is defined here
+  --> tests/ui/split_with_space.rs:4:8
+   |
+LL | #[deny(clippy::split_with_space)]
+   |        ^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: found call to `str::split` that uses the ASCII space character as an argument
+  --> tests/ui/split_with_space.rs:13:50
+   |
+LL |     for substr in some_space_delimtetered_string.split(" ") {
+   |                                                  ^ help: replace the use of `str::split` with `str::split_whitespace`
+
+error: aborting due to 2 previous errors
+

tests/versioncheck.rs

@@ -1,6 +1,6 @@
 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
 #![warn(rust_2018_idioms, unused_lifetimes)]
-#![allow(clippy::single_match_else)]
+#![allow(clippy::single_match_else, clippy::split_with_space)]
 
 use std::fs;