New lint [needless_raw_string_hashes]

CHANGELOG.md

@@ -5048,6 +5048,8 @@ 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_hashes`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_raw_string_hashes
+[`needless_raw_strings`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_raw_strings
 [`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
 [`needless_update`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_update
@@ -5412,4 +5414,5 @@ Released 2018-09-13
 [`min-ident-chars-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#min-ident-chars-threshold
 [`accept-comment-above-statement`]: https://doc.rust-lang.org/clippy/lint_configuration.html#accept-comment-above-statement
 [`accept-comment-above-attributes`]: https://doc.rust-lang.org/clippy/lint_configuration.html#accept-comment-above-attributes
+[`allow-one-hash-in-raw-strings`]: https://doc.rust-lang.org/clippy/lint_configuration.html#allow-one-hash-in-raw-strings
 <!-- end autogenerated links to configuration documentation -->

book/src/lint_configuration.md

@@ -717,3 +717,13 @@ Whether to accept a safety comment to be placed above the attributes for the `un
 * [`undocumented_unsafe_blocks`](https://rust-lang.github.io/rust-clippy/master/index.html#undocumented_unsafe_blocks)
 
 
+## `allow-one-hash-in-raw-strings`
+Whether to allow `r#""#` when `r""` can be used
+
+**Default Value:** `false` (`bool`)
+
+---
+**Affected lints:**
+* [`unnecessary_raw_string_hashes`](https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_raw_string_hashes)
+
+

clippy_lints/src/declared_lints.rs

@@ -540,6 +540,8 @@ 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_STRINGS_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

@@ -262,6 +262,7 @@ 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;
@@ -1061,6 +1062,12 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
             def_id_to_usage: rustc_data_structures::fx::FxHashMap::default(),
         })
     });
+    let needless_raw_string_hashes_allow_one = conf.allow_one_hash_in_raw_strings;
+    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/raw_strings.rs

@@ -0,0 +1,143 @@
+use std::{iter::once, ops::ControlFlow};
+
+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, but there are many cases where using a raw string literal is more
+    /// idiomatic than a string literal, so it's opt-in.
+    ///
+    /// ### Example
+    /// ```rust
+    /// let r = r"Hello, world!";
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// let r = "Hello, world!";
+    /// ```
+    #[clippy::version = "1.72.0"]
+    pub NEEDLESS_RAW_STRINGS,
+    restriction,
+    "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,
+    style,
+    "suggests reducing the number of hashes around a raw string literal"
+}
+impl_lint_pass!(RawStrings => [NEEDLESS_RAW_STRINGS, 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(max) | LitKind::ByteStrRaw(max) | LitKind::CStrRaw(max) = lit.kind
+        {
+            let str = lit.symbol.as_str();
+            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;
+            }
+
+            if !str.contains(['\\', '"']) {
+                span_lint_and_sugg(
+                    cx,
+                    NEEDLESS_RAW_STRINGS,
+                    expr.span,
+                    "unnecessary raw string literal",
+                    "try",
+                    format!("{}\"{}\"", prefix.replace('r', ""), lit.symbol),
+                    Applicability::MachineApplicable,
+                );
+
+                return;
+            }
+
+            let req = {
+                let mut following_quote = false;
+                let mut req = 0;
+                // `once` so a raw string ending in hashes is still checked
+                let num = str.as_bytes().iter().chain(once(&0)).try_fold(0u8, |acc, &b| {
+                    match b {
+                        b'"' => (following_quote, req) = (true, 1),
+                        // I'm a bit surprised the compiler didn't optimize this out, there's no
+                        // branch but it still ends up doing an unnecessary comparison, it's:
+                        // - cmp r9b,1h
+                        // - sbb cl,-1h
+                        // which will add 1 if it's true. With this change, it becomes:
+                        // - add cl,r9b
+                        // isn't that so much nicer?
+                        b'#' => req += u8::from(following_quote),
+                        _ => {
+                            if following_quote {
+                                following_quote = false;
+
+                                if req == max {
+                                    return ControlFlow::Break(req);
+                                }
+
+                                return ControlFlow::Continue(acc.max(req));
+                            }
+                        },
+                    }
+
+                    ControlFlow::Continue(acc)
+                });
+
+                match num {
+                    ControlFlow::Continue(num) | ControlFlow::Break(num) => num,
+                }
+            };
+
+            if req < max {
+                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,
+                );
+            }
+        }
+    }
+}

clippy_lints/src/utils/conf.rs

@@ -543,10 +543,14 @@ define_Conf! {
     ///
     /// Whether to accept a safety comment to be placed above the statement containing the `unsafe` block
     (accept_comment_above_statement: bool = false),
-        /// Lint: UNDOCUMENTED_UNSAFE_BLOCKS.
+    /// Lint: UNDOCUMENTED_UNSAFE_BLOCKS.
     ///
     /// Whether to accept a safety comment to be placed above the attributes for the `unsafe` block
     (accept_comment_above_attributes: bool = false),
+    /// Lint: UNNECESSARY_RAW_STRING_HASHES.
+    ///
+    /// Whether to allow `r#""#` when `r""` can be used
+    (allow_one_hash_in_raw_strings: bool = false),
 }
 
 /// Search for the configuration file.

clippy_lints/src/utils/internal_lints/almost_standard_lint_formulation.rs

@@ -35,7 +35,7 @@ struct StandardFormulations<'a> {
 impl AlmostStandardFormulation {
     pub fn new() -> Self {
         let standard_formulations = vec![StandardFormulations {
-            wrong_pattern: Regex::new(r"^(Check for|Detects? uses?)").unwrap(),
+            wrong_pattern: Regex::new("^(Check for|Detects? uses?)").unwrap(),
             correction: "Checks for",
         }];
         Self { standard_formulations }

src/main.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>...]
@@ -31,7 +31,7 @@ with:
 You can use tool lints to allow or deny lints from your code, e.g.:
 
     #[allow(clippy::needless_lifetimes)]
-"#;
+";
 
 fn show_help() {
     println!("{CARGO_CLIPPY_HELP}");

tests/compile-test.rs

@@ -50,7 +50,7 @@ fn base_config(test_dir: &str) -> compiletest::Config {
     config.program.args.push("-Dwarnings".into());
 
     // Normalize away slashes in windows paths.
-    config.stderr_filter(r#"\\"#, "/");
+    config.stderr_filter(r"\\", "/");
 
     //config.build_base = profile_path.join("test").join(test_dir);
     config.program.program = profile_path.join(if cfg!(windows) {

tests/lint_message_convention.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/ui-toml/toml_disallowed_methods/conf_disallowed_methods.rs

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