Add `--type` flag to `dev new_lint`

6 files changed, 295 insertions, 60 deletions

diff --git a/clippy_dev/src/main.rs b/clippy_dev/src/main.rs
index a29ba2d0c85..2008942d087 100644
--- a/clippy_dev/src/main.rs
+++ b/clippy_dev/src/main.rs
@@ -37,6 +37,7 @@ fn main() {
                 matches.get_one::<String>("pass"),
                 matches.get_one::<String>("name"),
                 matches.get_one::<String>("category"),
+                matches.get_one::<String>("type"),
                 matches.contains_id("msrv"),
             ) {
                 Ok(_) => update_lints::update(update_lints::UpdateMode::Change),
@@ -157,7 +158,8 @@ fn get_clap_config() -> ArgMatches {
                         .help("Specify whether the lint runs during the early or late pass")
                         .takes_value(true)
                         .value_parser([PossibleValue::new("early"), PossibleValue::new("late")])
-                        .required(true),
+                        .conflicts_with("type")
+                        .required_unless_present("type"),
                     Arg::new("name")
                         .short('n')
                         .long("name")
@@ -183,6 +185,11 @@ fn get_clap_config() -> ArgMatches {
                             PossibleValue::new("internal_warn"),
                         ])
                         .takes_value(true),
+                    Arg::new("type")
+                        .long("type")
+                        .help("What directory the lint belongs in")
+                        .takes_value(true)
+                        .required(false),
                     Arg::new("msrv").long("msrv").help("Add MSRV config code to the lint"),
                 ]),
             Command::new("setup")
diff --git a/clippy_dev/src/new_lint.rs b/clippy_dev/src/new_lint.rs
index 7d7e760ef44..af22cb89942 100644
--- a/clippy_dev/src/new_lint.rs
+++ b/clippy_dev/src/new_lint.rs
@@ -1,5 +1,5 @@
 use crate::clippy_project_root;
-use indoc::indoc;
+use indoc::{indoc, writedoc};
 use std::fmt::Write as _;
 use std::fs::{self, OpenOptions};
 use std::io::prelude::*;
@@ -10,6 +10,7 @@ struct LintData<'a> {
     pass: &'a str,
     name: &'a str,
     category: &'a str,
+    ty: Option<&'a str>,
     project_root: PathBuf,
 }
 
@@ -38,25 +39,35 @@ pub fn create(
     pass: Option<&String>,
     lint_name: Option<&String>,
     category: Option<&String>,
+    ty: Option<&String>,
     msrv: bool,
 ) -> io::Result<()> {
     let lint = LintData {
-        pass: pass.expect("`pass` argument is validated by clap"),
+        pass: pass.map_or("", String::as_str),
         name: lint_name.expect("`name` argument is validated by clap"),
         category: category.expect("`category` argument is validated by clap"),
+        ty: ty.map(String::as_str),
         project_root: clippy_project_root(),
     };
 
     create_lint(&lint, msrv).context("Unable to create lint implementation")?;
     create_test(&lint).context("Unable to create a test for the new lint")?;
-    add_lint(&lint, msrv).context("Unable to add lint to clippy_lints/src/lib.rs")
+
+    if lint.ty.is_none() {
+        add_lint(&lint, msrv).context("Unable to add lint to clippy_lints/src/lib.rs")?;
+    }
+
+    Ok(())
 }
 
 fn create_lint(lint: &LintData<'_>, enable_msrv: bool) -> io::Result<()> {
-    let lint_contents = get_lint_file_contents(lint, enable_msrv);
-
-    let lint_path = format!("clippy_lints/src/{}.rs", lint.name);
-    write_file(lint.project_root.join(&lint_path), lint_contents.as_bytes())
+    if let Some(ty) = lint.ty {
+        generate_from_ty(lint, enable_msrv, ty)
+    } else {
+        let lint_contents = get_lint_file_contents(lint, enable_msrv);
+        let lint_path = format!("clippy_lints/src/{}.rs", lint.name);
+        write_file(lint.project_root.join(&lint_path), lint_contents.as_bytes())
+    }
 }
 
 fn create_test(lint: &LintData<'_>) -> io::Result<()> {
@@ -204,7 +215,6 @@ fn get_lint_file_contents(lint: &LintData<'_>, enable_msrv: bool) -> String {
         },
     };
 
-    let version = get_stabilization_version();
     let lint_name = lint.name;
     let category = lint.category;
     let name_camel = to_camel_case(lint.name);
@@ -238,32 +248,7 @@ fn get_lint_file_contents(lint: &LintData<'_>, enable_msrv: bool) -> String {
         )
     });
 
-    let _ = write!(
-        result,
-        indoc! {r#"
-            declare_clippy_lint! {{
-                /// ### What it does
-                ///
-                /// ### Why is this bad?
-                ///
-                /// ### Example
-                /// ```rust
-                /// // example code where clippy issues a warning
-                /// ```
-                /// Use instead:
-                /// ```rust
-                /// // example code which does not raise clippy warning
-                /// ```
-                #[clippy::version = "{version}"]
-                pub {name_upper},
-                {category},
-                "default lint description"
-            }}
-        "#},
-        version = version,
-        name_upper = name_upper,
-        category = category,
-    );
+    let _ = write!(result, "{}", get_lint_declaration(&name_upper, category));
 
     result.push_str(&if enable_msrv {
         format!(
@@ -312,6 +297,247 @@ fn get_lint_file_contents(lint: &LintData<'_>, enable_msrv: bool) -> String {
     result
 }
 
+fn get_lint_declaration(name_upper: &str, category: &str) -> String {
+    format!(
+        indoc! {r#"
+            declare_clippy_lint! {{
+                /// ### What it does
+                ///
+                /// ### Why is this bad?
+                ///
+                /// ### Example
+                /// ```rust
+                /// // example code where clippy issues a warning
+                /// ```
+                /// Use instead:
+                /// ```rust
+                /// // example code which does not raise clippy warning
+                /// ```
+                #[clippy::version = "{version}"]
+                pub {name_upper},
+                {category},
+                "default lint description"
+            }}
+        "#},
+        version = get_stabilization_version(),
+        name_upper = name_upper,
+        category = category,
+    )
+}
+
+fn generate_from_ty(lint: &LintData<'_>, enable_msrv: bool, ty: &str) -> io::Result<()> {
+    if ty == "cargo" {
+        assert_eq!(
+            lint.category, "cargo",
+            "Lints of type `cargo` must have the `cargo` category"
+        );
+    }
+
+    let ty_dir = lint.project_root.join(format!("clippy_lints/src/{}", ty));
+    assert!(
+        ty_dir.exists() && ty_dir.is_dir(),
+        "Directory `{}` does not exist!",
+        ty_dir.display()
+    );
+
+    let lint_file_path = ty_dir.join(format!("{}.rs", lint.name));
+    assert!(
+        !lint_file_path.exists(),
+        "File `{}` already exists",
+        lint_file_path.display()
+    );
+
+    let mod_file_path = ty_dir.join("mod.rs");
+    let context_import = setup_mod_file(&mod_file_path, lint)?;
+
+    let name_upper = lint.name.to_uppercase();
+    let mut lint_file_contents = String::new();
+
+    if enable_msrv {
+        let _ = writedoc!(
+            lint_file_contents,
+            r#"
+                use clippy_utils::{{meets_msrv, msrvs}};
+                use rustc_lint::{{{context_import}, LintContext}};
+                use rustc_semver::RustcVersion;
+
+                use super::{name_upper};
+
+                // TODO: Adjust the parameters as necessary
+                pub(super) fn check(cx: &{context_import}, msrv: Option<RustcVersion>) {{
+                    if !meets_msrv(msrv, todo!("Add a new entry in `clippy_utils/src/msrvs`")) {{
+                        return;
+                    }}
+                    todo!();
+                }}
+           "#,
+            context_import = context_import,
+            name_upper = name_upper,
+        );
+    } else {
+        let _ = writedoc!(
+            lint_file_contents,
+            r#"
+                use rustc_lint::{{{context_import}, LintContext}};
+
+                use super::{name_upper};
+
+                // TODO: Adjust the parameters as necessary
+                pub(super) fn check(cx: &{context_import}) {{
+                    todo!();
+                }}
+           "#,
+            context_import = context_import,
+            name_upper = name_upper,
+        );
+    }
+
+    write_file(lint_file_path, lint_file_contents)?;
+
+    Ok(())
+}
+
+#[allow(clippy::too_many_lines)]
+fn setup_mod_file(path: &Path, lint: &LintData<'_>) -> io::Result<&'static str> {
+    use super::update_lints::{match_tokens, LintDeclSearchResult};
+    use rustc_lexer::TokenKind;
+
+    let lint_name_upper = lint.name.to_uppercase();
+
+    let mut file_contents = fs::read_to_string(path)?;
+    assert!(
+        !file_contents.contains(&lint_name_upper),
+        "Lint `{}` already defined in `{}`",
+        lint.name,
+        path.display()
+    );
+
+    let mut offset = 0usize;
+    let mut last_decl_curly_offset = None;
+    let mut lint_context = None;
+
+    let mut iter = rustc_lexer::tokenize(&file_contents).map(|t| {
+        let range = offset..offset + t.len;
+        offset = range.end;
+
+        LintDeclSearchResult {
+            token_kind: t.kind,
+            content: &file_contents[range.clone()],
+            range,
+        }
+    });
+
+    // Find both the last lint declaration (declare_clippy_lint!) and the lint pass impl
+    while let Some(LintDeclSearchResult { content, .. }) = iter.find(|result| result.token_kind == TokenKind::Ident) {
+        let mut iter = iter
+            .by_ref()
+            .filter(|t| !matches!(t.token_kind, TokenKind::Whitespace | TokenKind::LineComment { .. }));
+
+        match content {
+            "declare_clippy_lint" => {
+                // matches `!{`
+                match_tokens!(iter, Bang OpenBrace);
+                if let Some(LintDeclSearchResult { range, .. }) =
+                    iter.find(|result| result.token_kind == TokenKind::CloseBrace)
+                {
+                    last_decl_curly_offset = Some(range.end);
+                }
+            },
+            "impl" => {
+                let mut token = iter.next();
+                match token {
+                    // matches <'foo>
+                    Some(LintDeclSearchResult {
+                        token_kind: TokenKind::Lt,
+                        ..
+                    }) => {
+                        match_tokens!(iter, Lifetime { .. } Gt);
+                        token = iter.next();
+                    },
+                    None => break,
+                    _ => {},
+                }
+
+                if let Some(LintDeclSearchResult {
+                    token_kind: TokenKind::Ident,
+                    content,
+                    ..
+                }) = token
+                {
+                    // Get the appropriate lint context struct
+                    lint_context = match content {
+                        "LateLintPass" => Some("LateContext"),
+                        "EarlyLintPass" => Some("EarlyContext"),
+                        _ => continue,
+                    };
+                }
+            },
+            _ => {},
+        }
+    }
+
+    drop(iter);
+
+    let last_decl_curly_offset =
+        last_decl_curly_offset.unwrap_or_else(|| panic!("No lint declarations found in `{}`", path.display()));
+    let lint_context =
+        lint_context.unwrap_or_else(|| panic!("No lint pass implementation found in `{}`", path.display()));
+
+    // Add the lint declaration to `mod.rs`
+    file_contents.replace_range(
+        // Remove the trailing newline, which should always be present
+        last_decl_curly_offset..=last_decl_curly_offset,
+        &format!("\n\n{}", get_lint_declaration(&lint_name_upper, lint.category)),
+    );
+
+    // Add the lint to `impl_lint_pass`/`declare_lint_pass`
+    let impl_lint_pass_start = file_contents.find("impl_lint_pass!").unwrap_or_else(|| {
+        file_contents
+            .find("declare_lint_pass!")
+            .unwrap_or_else(|| panic!("failed to find `impl_lint_pass`/`declare_lint_pass`"))
+    });
+
+    let mut arr_start = file_contents[impl_lint_pass_start..].find('[').unwrap_or_else(|| {
+        panic!("malformed `impl_lint_pass`/`declare_lint_pass`");
+    });
+
+    arr_start += impl_lint_pass_start;
+
+    let mut arr_end = file_contents[arr_start..]
+        .find(']')
+        .expect("failed to find `impl_lint_pass` terminator");
+
+    arr_end += arr_start;
+
+    let mut arr_content = file_contents[arr_start + 1..arr_end].to_string();
+    arr_content.retain(|c| !c.is_whitespace());
+
+    let mut new_arr_content = String::new();
+    for ident in arr_content
+        .split(',')
+        .chain(std::iter::once(&*lint_name_upper))
+        .filter(|s| !s.is_empty())
+    {
+        let _ = write!(new_arr_content, "\n    {},", ident);
+    }
+    new_arr_content.push('\n');
+
+    file_contents.replace_range(arr_start + 1..arr_end, &new_arr_content);
+
+    // Just add the mod declaration at the top, it'll be fixed by rustfmt
+    file_contents.insert_str(0, &format!("mod {};\n", &lint.name));
+
+    let mut file = OpenOptions::new()
+        .write(true)
+        .truncate(true)
+        .open(path)
+        .context(format!("trying to open: `{}`", path.display()))?;
+    file.write_all(file_contents.as_bytes())
+        .context(format!("writing to file: `{}`", path.display()))?;
+
+    Ok(lint_context)
+}
+
 #[test]
 fn test_camel_case() {
     let s = "a_lint";
diff --git a/clippy_dev/src/update_lints.rs b/clippy_dev/src/update_lints.rs
index c089f4d8ce4..aed38bc2817 100644
--- a/clippy_dev/src/update_lints.rs
+++ b/clippy_dev/src/update_lints.rs
@@ -824,10 +824,12 @@ macro_rules! match_tokens {
     }
 }
 
-struct LintDeclSearchResult<'a> {
-    token_kind: TokenKind,
-    content: &'a str,
-    range: Range<usize>,
+pub(crate) use match_tokens;
+
+pub(crate) struct LintDeclSearchResult<'a> {
+    pub token_kind: TokenKind,
+    pub content: &'a str,
+    pub range: Range<usize>,
 }
 
 /// Parse a source file looking for `declare_clippy_lint` macro invocations.
diff --git a/clippy_lints/src/cargo/mod.rs b/clippy_lints/src/cargo/mod.rs
index abe95c6663f..9f45db86a09 100644
--- a/clippy_lints/src/cargo/mod.rs
+++ b/clippy_lints/src/cargo/mod.rs
@@ -1,3 +1,8 @@
+mod common_metadata;
+mod feature_name;
+mod multiple_crate_versions;
+mod wildcard_dependencies;
+
 use cargo_metadata::MetadataCommand;
 use clippy_utils::diagnostics::span_lint;
 use clippy_utils::is_lint_allowed;
@@ -6,11 +11,6 @@ use rustc_lint::{LateContext, LateLintPass, Lint};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::DUMMY_SP;
 
-mod common_metadata;
-mod feature_name;
-mod multiple_crate_versions;
-mod wildcard_dependencies;
-
 declare_clippy_lint! {
     /// ### What it does
     /// Checks to see if all common metadata is defined in
diff --git a/clippy_lints/src/matches/mod.rs b/clippy_lints/src/matches/mod.rs
index a3d69a4d09c..b638f271602 100644
--- a/clippy_lints/src/matches/mod.rs
+++ b/clippy_lints/src/matches/mod.rs
@@ -1,13 +1,3 @@
-use clippy_utils::source::{snippet_opt, span_starts_with, walk_span_to_context};
-use clippy_utils::{higher, in_constant, meets_msrv, msrvs};
-use rustc_hir::{Arm, Expr, ExprKind, Local, MatchSource, Pat};
-use rustc_lexer::{tokenize, TokenKind};
-use rustc_lint::{LateContext, LateLintPass, LintContext};
-use rustc_middle::lint::in_external_macro;
-use rustc_semver::RustcVersion;
-use rustc_session::{declare_tool_lint, impl_lint_pass};
-use rustc_span::{Span, SpanData, SyntaxContext};
-
 mod collapsible_match;
 mod infallible_destructuring_match;
 mod manual_map;
@@ -31,6 +21,16 @@ mod single_match;
 mod try_err;
 mod wild_in_or_pats;
 
+use clippy_utils::source::{snippet_opt, span_starts_with, walk_span_to_context};
+use clippy_utils::{higher, in_constant, meets_msrv, msrvs};
+use rustc_hir::{Arm, Expr, ExprKind, Local, MatchSource, Pat};
+use rustc_lexer::{tokenize, TokenKind};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_middle::lint::in_external_macro;
+use rustc_semver::RustcVersion;
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::{Span, SpanData, SyntaxContext};
+
 declare_clippy_lint! {
     /// ### What it does
     /// Checks for matches with a single arm where an `if let`
diff --git a/clippy_lints/src/operators/mod.rs b/clippy_lints/src/operators/mod.rs
index c688d94bb52..bb6d99406b4 100644
--- a/clippy_lints/src/operators/mod.rs
+++ b/clippy_lints/src/operators/mod.rs
@@ -1,9 +1,3 @@
-use rustc_hir::{Body, Expr, ExprKind, UnOp};
-use rustc_lint::{LateContext, LateLintPass};
-use rustc_session::{declare_tool_lint, impl_lint_pass};
-
-pub(crate) mod arithmetic;
-
 mod absurd_extreme_comparisons;
 mod assign_op_pattern;
 mod bit_mask;
@@ -27,6 +21,12 @@ mod ptr_eq;
 mod self_assignment;
 mod verbose_bit_mask;
 
+pub(crate) mod arithmetic;
+
+use rustc_hir::{Body, Expr, ExprKind, UnOp};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+
 declare_clippy_lint! {
     /// ### What it does
     /// Checks for comparisons where one side of the relation is