add needless_raw_string_hashes lint

add semicolon in doctest

clippy_lints/src/declared_lints.rs

@@ -469,6 +469,7 @@ pub(crate) static LINTS: &[&crate::LintInfo] = &[
     crate::needless_parens_on_range_literals::NEEDLESS_PARENS_ON_RANGE_LITERALS_INFO,
     crate::needless_pass_by_value::NEEDLESS_PASS_BY_VALUE_INFO,
     crate::needless_question_mark::NEEDLESS_QUESTION_MARK_INFO,
+    crate::needless_raw_string_hashes::NEEDLESS_RAW_STRING_HASHES_INFO,
     crate::needless_update::NEEDLESS_UPDATE_INFO,
     crate::neg_cmp_op_on_partial_ord::NEG_CMP_OP_ON_PARTIAL_ORD_INFO,
     crate::neg_multiply::NEG_MULTIPLY_INFO,

clippy_lints/src/lib.rs

@@ -230,6 +230,7 @@ mod needless_late_init;
 mod needless_parens_on_range_literals;
 mod needless_pass_by_value;
 mod needless_question_mark;
+mod needless_raw_string_hashes;
 mod needless_update;
 mod neg_cmp_op_on_partial_ord;
 mod neg_multiply;

clippy_lints/src/needless_raw_string_hashes.rs

@@ -0,0 +1,73 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use rustc_ast::{
+    ast::{Expr, ExprKind},
+    token::LitKind,
+};
+use rustc_errors::Applicability;
+use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_middle::lint::in_external_macro;
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for raw string literals with an unnecessary amount of hashes around them.
+    ///
+    /// ### Why is this bad?
+    /// It's just unnecessary, and makes it look like there's more escaping needed than is actually
+    /// necessary.
+    ///
+    /// ### Example
+    /// ```rust
+    /// let r = r###"Hello, "world"!"###;
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// let r = r#"Hello, "world"!"#;
+    /// ```
+    #[clippy::version = "1.72.0"]
+    pub NEEDLESS_RAW_STRING_HASHES,
+    complexity,
+    "suggests reducing the number of hashes around a raw string literal"
+}
+declare_lint_pass!(NeedlessRawStringHashes => [NEEDLESS_RAW_STRING_HASHES]);
+
+impl EarlyLintPass for NeedlessRawStringHashes {
+    fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
+        if_chain! {
+            if !in_external_macro(cx.sess(), expr.span);
+            if let ExprKind::Lit(lit) = expr.kind;
+            if let LitKind::StrRaw(num) | LitKind::ByteStrRaw(num) | LitKind::CStrRaw(num) = lit.kind;
+            then {
+                let str = lit.symbol.as_str();
+                let mut lowest = 0;
+
+                for i in (0..num).rev() {
+                    if str.contains(&format!("\"{}", "#".repeat(i as usize))) {
+                        lowest = i + 1;
+                        break;
+                    }
+                }
+
+                if lowest < num {
+                    let hashes = "#".repeat(lowest as usize);
+                    let prefix = match lit.kind {
+                        LitKind::StrRaw(..) => "r",
+                        LitKind::ByteStrRaw(..) => "br",
+                        LitKind::CStrRaw(..) => "cr",
+                        _ => unreachable!(),
+                    };
+
+                    span_lint_and_sugg(
+                        cx,
+                        NEEDLESS_RAW_STRING_HASHES,
+                        expr.span,
+                        "unnecessary hashes around raw string literal",
+                        "try",
+                        format!(r#"{prefix}{hashes}"{}"{hashes}"#, lit.symbol),
+                        Applicability::MachineApplicable,
+                    );
+                }
+            }
+        }
+    }
+}