new lint needless_raw_string + refactor a bit

Thanks, #112373, for the snippet at line 75!

Author: Centri3

CHANGELOG.md

@@ -5012,6 +5012,7 @@ Released 2018-09-13
 [`needless_pass_by_value`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_pass_by_value
 [`needless_question_mark`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_question_mark
 [`needless_range_loop`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_range_loop
+[`needless_raw_string`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_raw_string
 [`needless_raw_string_hashes`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_raw_string_hashes
 [`needless_return`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
 [`needless_splitn`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_splitn

clippy_lints/src/declared_lints.rs

@@ -456,7 +456,6 @@ 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,
@@ -528,6 +527,8 @@ pub(crate) static LINTS: &[&crate::LintInfo] = &[
     crate::ranges::RANGE_MINUS_ONE_INFO,
     crate::ranges::RANGE_PLUS_ONE_INFO,
     crate::ranges::REVERSED_EMPTY_RANGES_INFO,
+    crate::raw_strings::NEEDLESS_RAW_STRING_INFO,
+    crate::raw_strings::NEEDLESS_RAW_STRING_HASHES_INFO,
     crate::rc_clone_in_vec_init::RC_CLONE_IN_VEC_INIT_INFO,
     crate::read_zero_byte_vec::READ_ZERO_BYTE_VEC_INFO,
     crate::redundant_async_block::REDUNDANT_ASYNC_BLOCK_INFO,

clippy_lints/src/lib.rs

@@ -224,7 +224,6 @@ 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;
@@ -257,6 +256,7 @@ mod pub_use;
 mod question_mark;
 mod question_mark_used;
 mod ranges;
+mod raw_strings;
 mod rc_clone_in_vec_init;
 mod read_zero_byte_vec;
 mod redundant_async_block;
@@ -1008,7 +1008,12 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|_| Box::new(default_constructed_unit_structs::DefaultConstructedUnitStructs));
     store.register_early_pass(|| Box::new(needless_else::NeedlessElse));
     store.register_late_pass(|_| Box::new(missing_fields_in_debug::MissingFieldsInDebug));
-    store.register_early_pass(|| Box::new(needless_raw_string_hashes::NeedlessRawStringHashes));
+    let needless_raw_string_hashes_allow_one = conf.allow_one_hash_in_raw_string;
+    store.register_early_pass(move || {
+        Box::new(raw_strings::RawStrings {
+            needless_raw_string_hashes_allow_one,
+        })
+    });
     // add lints here, do not remove this comment, it's used in `new_lint`
 }
 

clippy_lints/src/needless_raw_string_hashes.rs

@@ -0,0 +1,109 @@
+use clippy_utils::{diagnostics::span_lint_and_sugg, source::snippet};
+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_tool_lint, impl_lint_pass};
+
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for raw string literals where a string literal can be used instead.
+    ///
+    /// ### Why is this bad?
+    /// It's just unnecessary.
+    ///
+    /// ### Example
+    /// ```rust
+    /// let r = r"Hello, world!";
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// let r = "Hello, "world"!";
+    /// ```
+    #[clippy::version = "1.72.0"]
+    pub NEEDLESS_RAW_STRING,
+    complexity,
+    "suggests using a string literal when a raw string literal is unnecessary"
+}
+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"
+}
+impl_lint_pass!(RawStrings => [NEEDLESS_RAW_STRING, NEEDLESS_RAW_STRING_HASHES]);
+
+pub struct RawStrings {
+    pub needless_raw_string_hashes_allow_one: bool,
+}
+
+impl EarlyLintPass for RawStrings {
+    fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
+        if !in_external_macro(cx.sess(), expr.span)
+            && let ExprKind::Lit(lit) = expr.kind
+            && let LitKind::StrRaw(num) | LitKind::ByteStrRaw(num) | LitKind::CStrRaw(num) = lit.kind
+        {
+            let prefix = match lit.kind {
+                LitKind::StrRaw(..) => "r",
+                LitKind::ByteStrRaw(..) => "br",
+                LitKind::CStrRaw(..) => "cr",
+                _ => unreachable!(),
+            };
+            if !snippet(cx, expr.span, prefix).trim().starts_with(prefix) {
+                return;
+            }
+
+            #[allow(clippy::cast_possible_truncation)]
+            let req = lit.symbol.as_str().as_bytes()
+                .split(|&b| b == b'"')
+                .skip(1)
+                .map(|bs| 1 + bs.iter().take_while(|&&b| b == b'#').count() as u8)
+                .max()
+                .unwrap_or(0);
+
+            if req < num {
+                let hashes = "#".repeat(req as usize);
+
+                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,
+                );
+            }
+
+            if !lit.symbol.as_str().contains(['\\', '"']) {
+                span_lint_and_sugg(
+                    cx,
+                    NEEDLESS_RAW_STRING,
+                    expr.span,
+                    "unnecessary raw string literal",
+                    "try",
+                    format!("{}\"{}\"", prefix.replace('r', ""), lit.symbol),
+                    Applicability::MachineApplicable,
+                );
+            }
+        }
+    }
+}

clippy_lints/src/raw_strings.rs

@@ -514,6 +514,10 @@ define_Conf! {
     ///
     /// The byte size a `T` in `Box<T>` can have, below which it triggers the `clippy::unnecessary_box` lint
     (unnecessary_box_size: u64 = 128),
+    /// Lint: UNNECESSARY_RAW_STRING_HASHES.
+    ///
+    /// Whether to allow `r#""#` when `r""` can be used
+    (allow_one_hash_in_raw_string: bool = false),
 }
 
 /// Search for the configuration file.

clippy_lints/src/utils/conf.rs

@@ -6,7 +6,7 @@ use std::env;
 use std::path::PathBuf;
 use std::process::{self, Command};
 
-const CARGO_CLIPPY_HELP: &str = r"Checks a package to catch common mistakes and improve your Rust code.
+const CARGO_CLIPPY_HELP: &str = "Checks a package to catch common mistakes and improve your Rust code.
 
 Usage:
     cargo clippy [options] [--] [<opts>...]

src/main.rs

@@ -20,16 +20,16 @@ impl Message {
         // also no punctuation (except for "?" ?) at the end of a line
         static REGEX_SET: LazyLock<RegexSet> = LazyLock::new(|| {
             RegexSet::new([
-                r"error: [A-Z]",
-                r"help: [A-Z]",
-                r"warning: [A-Z]",
-                r"note: [A-Z]",
-                r"try this: [A-Z]",
-                r"error: .*[.!]$",
-                r"help: .*[.!]$",
-                r"warning: .*[.!]$",
-                r"note: .*[.!]$",
-                r"try this: .*[.!]$",
+                "error: [A-Z]",
+                "help: [A-Z]",
+                "warning: [A-Z]",
+                "note: [A-Z]",
+                "try this: [A-Z]",
+                "error: .*[.!]$",
+                "help: .*[.!]$",
+                "warning: .*[.!]$",
+                "note: .*[.!]$",
+                "try this: .*[.!]$",
             ])
             .unwrap()
         });
@@ -39,11 +39,11 @@ impl Message {
         static EXCEPTIONS_SET: LazyLock<RegexSet> = LazyLock::new(|| {
             RegexSet::new([
                 r"\.\.\.$",
-                r".*C-like enum variant discriminant is not portable to 32-bit targets",
-                r".*Intel x86 assembly syntax used",
-                r".*AT&T x86 assembly syntax used",
-                r"note: Clippy version: .*",
-                r"the compiler unexpectedly panicked. this is a bug.",
+                ".*C-like enum variant discriminant is not portable to 32-bit targets",
+                ".*Intel x86 assembly syntax used",
+                ".*AT&T x86 assembly syntax used",
+                "note: Clippy version: .*",
+                "the compiler unexpectedly panicked. this is a bug.",
             ])
             .unwrap()
         });

tests/lint_message_convention.rs

@@ -1,5 +1,6 @@
 //@compile-flags: --crate-name conf_disallowed_methods
 
+#![allow(clippy::needless_raw_string)]
 #![warn(clippy::disallowed_methods)]
 
 extern crate futures;