8733: Make docs more precise and add description of known problems

clippy_lints/src/methods/mod.rs

@@ -3837,7 +3837,7 @@ declare_clippy_lint! {
     ///
     /// ### Why is this bad?
     ///
-    /// Hard-coding the line endings makes the code less portable. `str.lines` should be used instead.
+    /// Hard-coding the line endings makes the code less compatible. `str.lines` should be used instead.
     ///
     /// ### Example
     /// ```no_run
@@ -3847,6 +3847,13 @@ declare_clippy_lint! {
     /// ```no_run
     /// "some\ntext\nwith\nnewlines\n".lines();
     /// ```
+    ///
+    /// ### Known Problems
+    ///
+    /// This lint cannot detect if the split is intentionally restricted to a single type of newline (`"\n"` or
+    /// `"\r\n"`), for example during the parsing of a specific file format in which precisely one newline type is
+    /// valid.
+    /// ```
     #[clippy::version = "1.76.0"]
     pub STR_SPLIT_AT_NEWLINE,
     pedantic,

clippy_lints/src/methods/str_split.rs

@@ -9,11 +9,10 @@ use rustc_lint::LateContext;
 use super::STR_SPLIT_AT_NEWLINE;
 
 pub(super) fn check<'a>(cx: &LateContext<'a>, expr: &'_ Expr<'_>, split_recv: &'a Expr<'_>, split_arg: &'_ Expr<'_>) {
-    // We're looking for `A.trim().split(B)`, where the adjusted type of `A` is `&str` (e.g. a `str`
-    // literal or an expression returning `String`), and `B` is a `Pattern` that hard-codes a
-    // newline (either `"\n"` or `"\r\n"`). There are a lot of ways to specify a pattern, and
-    // this lint only checks the most basic ones: a `'\n'`, `"\n"`, and `"\r\n"`.
-
+    // We're looking for `A.trim().split(B)`, where the adjusted type of `A` is `&str` (e.g. an
+    // expression returning `String`), and `B` is a `Pattern` that hard-codes a newline (either `"\n"`
+    // or `"\r\n"`). There are a lot of ways to specify a pattern, and this lint only checks the most
+    // basic ones: a `'\n'`, `"\n"`, and `"\r\n"`.
     if let ExprKind::MethodCall(trim_method_name, trim_recv, [], _) = split_recv.kind
         && trim_method_name.ident.as_str() == "trim"
         && cx.typeck_results().expr_ty_adjusted(trim_recv).peel_refs().is_str()