Auto merge of rust-lang#7880 - Alexendoo:newlint-add-pass, r=flip1995

Register the generated lints from `cargo dev new_lint`

How to register a lint was something that took me a couple reads to figure out, this will hopefully make that easier. It appends the created lint to the end of the list when running `cargo dev new_lint`

changelog: none

Author: bors

clippy_dev/src/new_lint.rs

@@ -42,7 +42,8 @@ pub fn create(pass: Option<&str>, lint_name: Option<&str>, category: Option<&str
     };
 
     create_lint(&lint, msrv).context("Unable to create lint implementation")?;
-    create_test(&lint).context("Unable to create a test for the new lint")
+    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")
 }
 
 fn create_lint(lint: &LintData<'_>, enable_msrv: bool) -> io::Result<()> {
@@ -80,6 +81,33 @@ fn create_test(lint: &LintData<'_>) -> io::Result<()> {
     }
 }
 
+fn add_lint(lint: &LintData<'_>, enable_msrv: bool) -> io::Result<()> {
+    let path = "clippy_lints/src/lib.rs";
+    let mut lib_rs = fs::read_to_string(path).context("reading")?;
+
+    let comment_start = lib_rs.find("// add lints here,").expect("Couldn't find comment");
+
+    let new_lint = if enable_msrv {
+        format!(
+            "store.register_{lint_pass}_pass(move || Box::new({module_name}::{camel_name}::new(msrv)));\n    ",
+            lint_pass = lint.pass,
+            module_name = lint.name,
+            camel_name = to_camel_case(lint.name),
+        )
+    } else {
+        format!(
+            "store.register_{lint_pass}_pass(|| Box::new({module_name}::{camel_name}));\n    ",
+            lint_pass = lint.pass,
+            module_name = lint.name,
+            camel_name = to_camel_case(lint.name),
+        )
+    };
+
+    lib_rs.insert_str(comment_start, &new_lint);
+
+    fs::write(path, lib_rs).context("writing")
+}
+
 fn write_file<P: AsRef<Path>, C: AsRef<[u8]>>(path: P, contents: C) -> io::Result<()> {
     fn inner(path: &Path, contents: &[u8]) -> io::Result<()> {
         OpenOptions::new()
@@ -151,7 +179,6 @@ fn get_lint_file_contents(lint: &LintData<'_>, enable_msrv: bool) -> String {
     };
 
     let lint_name = lint.name;
-    let pass_name = lint.pass;
     let category = lint.category;
     let name_camel = to_camel_case(lint.name);
     let name_upper = lint_name.to_uppercase();
@@ -228,18 +255,14 @@ fn get_lint_file_contents(lint: &LintData<'_>, enable_msrv: bool) -> String {
                     extract_msrv_attr!({context_import});
                 }}
 
-                // TODO: Register the lint pass in `clippy_lints/src/lib.rs`,
-                //       e.g. store.register_{pass_name}_pass(move || Box::new({module_name}::{name_camel}::new(msrv)));
                 // TODO: Add MSRV level to `clippy_utils/src/msrvs.rs` if needed.
                 // TODO: Add MSRV test to `tests/ui/min_rust_version_attr.rs`.
                 // TODO: Update msrv config comment in `clippy_lints/src/utils/conf.rs`
             "},
             pass_type = pass_type,
             pass_lifetimes = pass_lifetimes,
-            pass_name = pass_name,
             name_upper = name_upper,
             name_camel = name_camel,
-            module_name = lint_name,
             context_import = context_import,
         )
     } else {
@@ -248,16 +271,11 @@ fn get_lint_file_contents(lint: &LintData<'_>, enable_msrv: bool) -> String {
                 declare_lint_pass!({name_camel} => [{name_upper}]);
 
                 impl {pass_type}{pass_lifetimes} for {name_camel} {{}}
-                //
-                // TODO: Register the lint pass in `clippy_lints/src/lib.rs`,
-                //       e.g. store.register_{pass_name}_pass(|| Box::new({module_name}::{name_camel}));
             "},
             pass_type = pass_type,
             pass_lifetimes = pass_lifetimes,
-            pass_name = pass_name,
             name_upper = name_upper,
             name_camel = name_camel,
-            module_name = lint_name,
         )
     });
 

clippy_lints/src/lib.rs

@@ -777,7 +777,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| Box::new(match_str_case_mismatch::MatchStrCaseMismatch));
     store.register_late_pass(move || Box::new(format_args::FormatArgs));
     store.register_late_pass(|| Box::new(trailing_empty_array::TrailingEmptyArray));
-
+    // add lints here, do not remove this comment, it's used in `new_lint`
 }
 
 #[rustfmt::skip]

doc/adding_lints.md

@@ -16,6 +16,7 @@ because that's clearly a non-descriptive name.
   - [Edition 2018 tests](#edition-2018-tests)
   - [Testing manually](#testing-manually)
   - [Lint declaration](#lint-declaration)
+  - [Lint registration](#lint-registration)
   - [Lint passes](#lint-passes)
   - [Emitting a lint](#emitting-a-lint)
   - [Adding the lint logic](#adding-the-lint-logic)
@@ -43,9 +44,9 @@ take a look at our [lint naming guidelines][lint_naming]. To get started on this
 lint you can run `cargo dev new_lint --name=foo_functions --pass=early
 --category=pedantic` (category will default to nursery if not provided). This
 command will create two files: `tests/ui/foo_functions.rs` and
-`clippy_lints/src/foo_functions.rs`, as well as run `cargo dev update_lints` to
-register the new lint. For cargo lints, two project hierarchies (fail/pass) will
-be created by default under `tests/ui-cargo`.
+`clippy_lints/src/foo_functions.rs`, as well as
+[registering the lint](#lint-registration). For cargo lints, two project
+hierarchies (fail/pass) will be created by default under `tests/ui-cargo`.
 
 Next, we'll open up these files and add our lint!
 
@@ -220,32 +221,34 @@ declare_lint_pass!(FooFunctions => [FOO_FUNCTIONS]);
 impl EarlyLintPass for FooFunctions {}
 ```
 
-Normally after declaring the lint, we have to run `cargo dev update_lints`,
-which updates some files, so Clippy knows about the new lint. Since we used
-`cargo dev new_lint ...` to generate the lint declaration, this was done
-automatically. While `update_lints` automates most of the things, it doesn't
-automate everything. We will have to register our lint pass manually in the
-`register_plugins` function in `clippy_lints/src/lib.rs`:
+[declare_clippy_lint]: https://github.com/rust-lang/rust-clippy/blob/557f6848bd5b7183f55c1e1522a326e9e1df6030/clippy_lints/src/lib.rs#L60
+[example_lint_page]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure
+[lint_naming]: https://rust-lang.github.io/rfcs/0344-conventions-galore.html#lints
+[category_level_mapping]: https://github.com/rust-lang/rust-clippy/blob/557f6848bd5b7183f55c1e1522a326e9e1df6030/clippy_lints/src/lib.rs#L110
+
+## Lint registration
+
+When using `cargo dev new_lint`, the lint is automatically registered and
+nothing more has to be done.
+
+When declaring a new lint by hand and `cargo dev update_lints` is used, the lint
+pass may have to be registered manually in the `register_plugins` function in
+`clippy_lints/src/lib.rs`:
 
 ```rust
-store.register_early_pass(|| box foo_functions::FooFunctions);
+store.register_early_pass(|| Box::new(foo_functions::FooFunctions));
 ```
 
 As one may expect, there is a corresponding `register_late_pass` method
 available as well. Without a call to one of `register_early_pass` or
 `register_late_pass`, the lint pass in question will not be run.
 
-One reason that `cargo dev` does not automate this step is that multiple lints
-can use the same lint pass, so registering the lint pass may already be done
-when adding a new lint. Another reason that this step is not automated is that
-the order that the passes are registered determines the order the passes
-actually run, which in turn affects the order that any emitted lints are output
-in.
-
-[declare_clippy_lint]: https://github.com/rust-lang/rust-clippy/blob/557f6848bd5b7183f55c1e1522a326e9e1df6030/clippy_lints/src/lib.rs#L60
-[example_lint_page]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure
-[lint_naming]: https://rust-lang.github.io/rfcs/0344-conventions-galore.html#lints
-[category_level_mapping]: https://github.com/rust-lang/rust-clippy/blob/557f6848bd5b7183f55c1e1522a326e9e1df6030/clippy_lints/src/lib.rs#L110
+One reason that `cargo dev update_lints` does not automate this step is that
+multiple lints can use the same lint pass, so registering the lint pass may
+already be done when adding a new lint. Another reason that this step is not
+automated is that the order that the passes are registered determines the order
+the passes actually run, which in turn affects the order that any emitted lints
+are output in.
 
 ## Lint passes