Auto merge of #7560 - xFrednet:7289-configuration-for-every-type-lint, r=camsteffen

Use `avoid-breaking-exported-api` configuration in types module

This PR empowers our lovely `avoid-breaking-exported-api` configuration value to also influence the emission of lints inside the `types` module.

(That's pretty much it, not really a change worthy of writing a fairy tale about. Don't get me wrong, I would love to write a short one, but I sadly need to study now).

---

Closes: rust-lang/rust-clippy#7489

changelog: The `avoid-breaking-exported-api` configuration now also works for [`box_vec`], [`redundant_allocation`], [`rc_buffer`], [`vec_box`], [`option_option`], [`linkedlist`], [`rc_mutex`]

changelog: [`rc_mutex`]: update the lint message to comply with the normal format

---

r? `@camsteffen,` as you implemented the configuration value

cc: `@flip1995,` as we've discussed this change in rust-lang/rust-clippy#7308

10 files changed, 167 insertions, 88 deletions

diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index dbdb4251b3b..18600498e1c 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -1840,7 +1840,12 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| box serde_api::SerdeApi);
     let vec_box_size_threshold = conf.vec_box_size_threshold;
     let type_complexity_threshold = conf.type_complexity_threshold;
-    store.register_late_pass(move || box types::Types::new(vec_box_size_threshold, type_complexity_threshold));
+    let avoid_breaking_exported_api = conf.avoid_breaking_exported_api;
+    store.register_late_pass(move || box types::Types::new(
+        vec_box_size_threshold,
+        type_complexity_threshold,
+        avoid_breaking_exported_api,
+    ));
     store.register_late_pass(|| box booleans::NonminimalBool);
     store.register_late_pass(|| box needless_bitwise_bool::NeedlessBitwiseBool);
     store.register_late_pass(|| box eq_op::EqOp);
diff --git a/clippy_lints/src/types/mod.rs b/clippy_lints/src/types/mod.rs
index 371bb8b445a..9588de8459c 100644
--- a/clippy_lints/src/types/mod.rs
+++ b/clippy_lints/src/types/mod.rs
@@ -295,6 +295,7 @@ declare_clippy_lint! {
 pub struct Types {
     vec_box_size_threshold: u64,
     type_complexity_threshold: u64,
+    avoid_breaking_exported_api: bool,
 }
 
 impl_lint_pass!(Types => [BOX_VEC, VEC_BOX, OPTION_OPTION, LINKEDLIST, BORROWED_BOX, REDUNDANT_ALLOCATION, RC_BUFFER, RC_MUTEX, TYPE_COMPLEXITY]);
@@ -308,19 +309,31 @@ impl<'tcx> LateLintPass<'tcx> for Types {
             false
         };
 
+        let is_exported = cx.access_levels.is_exported(cx.tcx.hir().local_def_id(id));
+
         self.check_fn_decl(
             cx,
             decl,
             CheckTyContext {
                 is_in_trait_impl,
+                is_exported,
                 ..CheckTyContext::default()
             },
         );
     }
 
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
+        let is_exported = cx.access_levels.is_exported(item.def_id);
+
         match item.kind {
-            ItemKind::Static(ty, _, _) | ItemKind::Const(ty, _) => self.check_ty(cx, ty, CheckTyContext::default()),
+            ItemKind::Static(ty, _, _) | ItemKind::Const(ty, _) => self.check_ty(
+                cx,
+                ty,
+                CheckTyContext {
+                    is_exported,
+                    ..CheckTyContext::default()
+                },
+            ),
             // functions, enums, structs, impls and traits are covered
             _ => (),
         }
@@ -342,15 +355,31 @@ impl<'tcx> LateLintPass<'tcx> for Types {
     }
 
     fn check_field_def(&mut self, cx: &LateContext<'_>, field: &hir::FieldDef<'_>) {
-        self.check_ty(cx, field.ty, CheckTyContext::default());
+        let is_exported = cx.access_levels.is_exported(cx.tcx.hir().local_def_id(field.hir_id));
+
+        self.check_ty(
+            cx,
+            field.ty,
+            CheckTyContext {
+                is_exported,
+                ..CheckTyContext::default()
+            },
+        );
     }
 
-    fn check_trait_item(&mut self, cx: &LateContext<'_>, item: &TraitItem<'_>) {
+    fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &TraitItem<'_>) {
+        let is_exported = cx.access_levels.is_exported(item.def_id);
+
+        let context = CheckTyContext {
+            is_exported,
+            ..CheckTyContext::default()
+        };
+
         match item.kind {
             TraitItemKind::Const(ty, _) | TraitItemKind::Type(_, Some(ty)) => {
-                self.check_ty(cx, ty, CheckTyContext::default());
+                self.check_ty(cx, ty, context);
             },
-            TraitItemKind::Fn(ref sig, _) => self.check_fn_decl(cx, sig.decl, CheckTyContext::default()),
+            TraitItemKind::Fn(ref sig, _) => self.check_fn_decl(cx, sig.decl, context),
             TraitItemKind::Type(..) => (),
         }
     }
@@ -370,10 +399,11 @@ impl<'tcx> LateLintPass<'tcx> for Types {
 }
 
 impl Types {
-    pub fn new(vec_box_size_threshold: u64, type_complexity_threshold: u64) -> Self {
+    pub fn new(vec_box_size_threshold: u64, type_complexity_threshold: u64, avoid_breaking_exported_api: bool) -> Self {
         Self {
             vec_box_size_threshold,
             type_complexity_threshold,
+            avoid_breaking_exported_api,
         }
     }
 
@@ -410,17 +440,24 @@ impl Types {
                 let hir_id = hir_ty.hir_id;
                 let res = cx.qpath_res(qpath, hir_id);
                 if let Some(def_id) = res.opt_def_id() {
-                    let mut triggered = false;
-                    triggered |= box_vec::check(cx, hir_ty, qpath, def_id);
-                    triggered |= redundant_allocation::check(cx, hir_ty, qpath, def_id);
-                    triggered |= rc_buffer::check(cx, hir_ty, qpath, def_id);
-                    triggered |= vec_box::check(cx, hir_ty, qpath, def_id, self.vec_box_size_threshold);
-                    triggered |= option_option::check(cx, hir_ty, qpath, def_id);
-                    triggered |= linked_list::check(cx, hir_ty, def_id);
-                    triggered |= rc_mutex::check(cx, hir_ty, qpath, def_id);
-
-                    if triggered {
-                        return;
+                    if self.is_type_change_allowed(context) {
+                        // All lints that are being checked in this block are guarded by
+                        // the `avoid_breaking_exported_api` configuration. When adding a
+                        // new lint, please also add the name to the configuration documentation
+                        // in `clippy_lints::utils::conf.rs`
+
+                        let mut triggered = false;
+                        triggered |= box_vec::check(cx, hir_ty, qpath, def_id);
+                        triggered |= redundant_allocation::check(cx, hir_ty, qpath, def_id);
+                        triggered |= rc_buffer::check(cx, hir_ty, qpath, def_id);
+                        triggered |= vec_box::check(cx, hir_ty, qpath, def_id, self.vec_box_size_threshold);
+                        triggered |= option_option::check(cx, hir_ty, qpath, def_id);
+                        triggered |= linked_list::check(cx, hir_ty, def_id);
+                        triggered |= rc_mutex::check(cx, hir_ty, qpath, def_id);
+
+                        if triggered {
+                            return;
+                        }
                     }
                 }
                 match *qpath {
@@ -487,11 +524,21 @@ impl Types {
             _ => {},
         }
     }
+
+    /// This function checks if the type is allowed to change in the current context
+    /// based on the `avoid_breaking_exported_api` configuration
+    fn is_type_change_allowed(&self, context: CheckTyContext) -> bool {
+        !(context.is_exported && self.avoid_breaking_exported_api)
+    }
 }
 
+#[allow(clippy::struct_excessive_bools)]
 #[derive(Clone, Copy, Default)]
 struct CheckTyContext {
     is_in_trait_impl: bool,
+    /// `true` for types on local variables.
     is_local: bool,
+    /// `true` for types that are part of the public API.
+    is_exported: bool,
     is_nested_call: bool,
 }
diff --git a/clippy_lints/src/types/rc_mutex.rs b/clippy_lints/src/types/rc_mutex.rs
index bd7a0ee6408..12db7afb81c 100644
--- a/clippy_lints/src/types/rc_mutex.rs
+++ b/clippy_lints/src/types/rc_mutex.rs
@@ -1,4 +1,4 @@
-use clippy_utils::diagnostics::span_lint;
+use clippy_utils::diagnostics::span_lint_and_help;
 use clippy_utils::is_ty_param_diagnostic_item;
 use if_chain::if_chain;
 use rustc_hir::{self as hir, def_id::DefId, QPath};
@@ -11,13 +11,14 @@ pub(super) fn check(cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>, qpath: &QPath<'_
     if_chain! {
         if cx.tcx.is_diagnostic_item(sym::Rc, def_id) ;
         if let Some(_) = is_ty_param_diagnostic_item(cx, qpath, sym!(mutex_type)) ;
-
-        then{
-            span_lint(
+        then {
+            span_lint_and_help(
                 cx,
                 RC_MUTEX,
                 hir_ty.span,
-                "found `Rc<Mutex<_>>`. Consider using `Rc<RefCell<_>>` or `Arc<Mutex<_>>` instead",
+                "usage of `Rc<Mutex<_>>`",
+                None,
+                "consider using `Rc<RefCell<_>>` or `Arc<Mutex<_>>` instead",
             );
             return true;
         }
diff --git a/clippy_lints/src/utils/conf.rs b/clippy_lints/src/utils/conf.rs
index a28b1d78f7d..9ee2e302452 100644
--- a/clippy_lints/src/utils/conf.rs
+++ b/clippy_lints/src/utils/conf.rs
@@ -132,7 +132,7 @@ macro_rules! define_Conf {
 
 // N.B., this macro is parsed by util/lintlib.py
 define_Conf! {
-    /// Lint: ENUM_VARIANT_NAMES, LARGE_TYPES_PASSED_BY_VALUE, TRIVIALLY_COPY_PASS_BY_REF, UNNECESSARY_WRAPS, UPPER_CASE_ACRONYMS, WRONG_SELF_CONVENTION.
+    /// Lint: ENUM_VARIANT_NAMES, LARGE_TYPES_PASSED_BY_VALUE, TRIVIALLY_COPY_PASS_BY_REF, UNNECESSARY_WRAPS, UPPER_CASE_ACRONYMS, WRONG_SELF_CONVENTION, BOX_VEC, REDUNDANT_ALLOCATION, RC_BUFFER, VEC_BOX, OPTION_OPTION, LINKEDLIST, RC_MUTEX.
     ///
     /// Suppress lints whenever the suggested change would cause breakage for other crates.
     (avoid_breaking_exported_api: bool = true),
diff --git a/tests/ui/box_vec.rs b/tests/ui/box_vec.rs
index 87b67c23704..1d6366972da 100644
--- a/tests/ui/box_vec.rs
+++ b/tests/ui/box_vec.rs
@@ -1,6 +1,10 @@
 #![warn(clippy::all)]
-#![allow(clippy::boxed_local, clippy::needless_pass_by_value)]
-#![allow(clippy::blacklisted_name)]
+#![allow(
+    clippy::boxed_local,
+    clippy::needless_pass_by_value,
+    clippy::blacklisted_name,
+    unused
+)]
 
 macro_rules! boxit {
     ($init:expr, $x:ty) => {
@@ -11,22 +15,22 @@ macro_rules! boxit {
 fn test_macro() {
     boxit!(Vec::new(), Vec<u8>);
 }
-pub fn test(foo: Box<Vec<bool>>) {
-    println!("{:?}", foo.get(0))
-}
+fn test(foo: Box<Vec<bool>>) {}
 
-pub fn test2(foo: Box<dyn Fn(Vec<u32>)>) {
+fn test2(foo: Box<dyn Fn(Vec<u32>)>) {
     // pass if #31 is fixed
     foo(vec![1, 2, 3])
 }
 
-pub fn test_local_not_linted() {
+fn test_local_not_linted() {
     let _: Box<Vec<bool>>;
 }
 
-fn main() {
-    test(Box::new(Vec::new()));
-    test2(Box::new(|v| println!("{:?}", v)));
-    test_macro();
-    test_local_not_linted();
+// All of these test should be allowed because they are part of the
+// public api and `avoid_breaking_exported_api` is `false` by default.
+pub fn pub_test(foo: Box<Vec<bool>>) {}
+pub fn pub_test_ret() -> Box<Vec<bool>> {
+    Box::new(Vec::new())
 }
+
+fn main() {}
diff --git a/tests/ui/box_vec.stderr b/tests/ui/box_vec.stderr
index 9b789334bae..58c1f13fb87 100644
--- a/tests/ui/box_vec.stderr
+++ b/tests/ui/box_vec.stderr
@@ -1,8 +1,8 @@
 error: you seem to be trying to use `Box<Vec<T>>`. Consider using just `Vec<T>`
-  --> $DIR/box_vec.rs:14:18
+  --> $DIR/box_vec.rs:18:14
    |
-LL | pub fn test(foo: Box<Vec<bool>>) {
-   |                  ^^^^^^^^^^^^^^
+LL | fn test(foo: Box<Vec<bool>>) {}
+   |              ^^^^^^^^^^^^^^
    |
    = note: `-D clippy::box-vec` implied by `-D warnings`
    = help: `Vec<T>` is already on the heap, `Box<Vec<T>>` makes an extra allocation
diff --git a/tests/ui/linkedlist.rs b/tests/ui/linkedlist.rs
index 2c3b25cd45e..690ea810a62 100644
--- a/tests/ui/linkedlist.rs
+++ b/tests/ui/linkedlist.rs
@@ -1,6 +1,6 @@
 #![feature(associated_type_defaults)]
 #![warn(clippy::linkedlist)]
-#![allow(dead_code, clippy::needless_pass_by_value)]
+#![allow(unused, dead_code, clippy::needless_pass_by_value)]
 
 extern crate alloc;
 use alloc::collections::linked_list::LinkedList;
@@ -20,24 +20,29 @@ impl Foo for LinkedList<u8> {
     const BAR: Option<LinkedList<u8>> = None;
 }
 
-struct Bar;
+pub struct Bar {
+    priv_linked_list_field: LinkedList<u8>,
+    pub pub_linked_list_field: LinkedList<u8>,
+}
 impl Bar {
     fn foo(_: LinkedList<u8>) {}
 }
 
-pub fn test(my_favourite_linked_list: LinkedList<u8>) {
-    println!("{:?}", my_favourite_linked_list)
-}
-
-pub fn test_ret() -> Option<LinkedList<u8>> {
-    unimplemented!();
+// All of these test should be trigger the lint because they are not
+// part of the public api
+fn test(my_favorite_linked_list: LinkedList<u8>) {}
+fn test_ret() -> Option<LinkedList<u8>> {
+    None
 }
-
-pub fn test_local_not_linted() {
+fn test_local_not_linted() {
     let _: LinkedList<u8>;
 }
 
-fn main() {
-    test(LinkedList::new());
-    test_local_not_linted();
+// All of these test should be allowed because they are part of the
+// public api and `avoid_breaking_exported_api` is `false` by default.
+pub fn pub_test(the_most_awesome_linked_list: LinkedList<u8>) {}
+pub fn pub_test_ret() -> Option<LinkedList<u8>> {
+    None
 }
+
+fn main() {}
diff --git a/tests/ui/linkedlist.stderr b/tests/ui/linkedlist.stderr
index 38ae71714d6..51327df1321 100644
--- a/tests/ui/linkedlist.stderr
+++ b/tests/ui/linkedlist.stderr
@@ -40,7 +40,15 @@ LL |     const BAR: Option<LinkedList<u8>>;
    = help: a `VecDeque` might work
 
 error: you seem to be using a `LinkedList`! Perhaps you meant some other data structure?
-  --> $DIR/linkedlist.rs:25:15
+  --> $DIR/linkedlist.rs:24:29
+   |
+LL |     priv_linked_list_field: LinkedList<u8>,
+   |                             ^^^^^^^^^^^^^^
+   |
+   = help: a `VecDeque` might work
+
+error: you seem to be using a `LinkedList`! Perhaps you meant some other data structure?
+  --> $DIR/linkedlist.rs:28:15
    |
 LL |     fn foo(_: LinkedList<u8>) {}
    |               ^^^^^^^^^^^^^^
@@ -48,20 +56,20 @@ LL |     fn foo(_: LinkedList<u8>) {}
    = help: a `VecDeque` might work
 
 error: you seem to be using a `LinkedList`! Perhaps you meant some other data structure?
-  --> $DIR/linkedlist.rs:28:39
+  --> $DIR/linkedlist.rs:33:34
    |
-LL | pub fn test(my_favourite_linked_list: LinkedList<u8>) {
-   |                                       ^^^^^^^^^^^^^^
+LL | fn test(my_favorite_linked_list: LinkedList<u8>) {}
+   |                                  ^^^^^^^^^^^^^^
    |
    = help: a `VecDeque` might work
 
 error: you seem to be using a `LinkedList`! Perhaps you meant some other data structure?
-  --> $DIR/linkedlist.rs:32:29
+  --> $DIR/linkedlist.rs:34:25
    |
-LL | pub fn test_ret() -> Option<LinkedList<u8>> {
-   |                             ^^^^^^^^^^^^^^
+LL | fn test_ret() -> Option<LinkedList<u8>> {
+   |                         ^^^^^^^^^^^^^^
    |
    = help: a `VecDeque` might work
 
-error: aborting due to 8 previous errors
+error: aborting due to 9 previous errors
 
diff --git a/tests/ui/rc_mutex.rs b/tests/ui/rc_mutex.rs
index 657a3ecf6a0..18e8a2e01e0 100644
--- a/tests/ui/rc_mutex.rs
+++ b/tests/ui/rc_mutex.rs
@@ -1,13 +1,17 @@
 #![warn(clippy::rc_mutex)]
-#![allow(clippy::blacklisted_name)]
+#![allow(unused, clippy::blacklisted_name)]
 
 use std::rc::Rc;
 use std::sync::Mutex;
 
-pub struct MyStruct {
+pub struct MyStructWithPrivItem {
     foo: Rc<Mutex<i32>>,
 }
 
+pub struct MyStructWithPubItem {
+    pub foo: Rc<Mutex<i32>>,
+}
+
 pub struct SubT<T> {
     foo: T,
 }
@@ -17,18 +21,16 @@ pub enum MyEnum {
     Two,
 }
 
-pub fn test1<T>(foo: Rc<Mutex<T>>) {}
-
-pub fn test2(foo: Rc<Mutex<MyEnum>>) {}
+// All of these test should be trigger the lint because they are not
+// part of the public api
+fn test1<T>(foo: Rc<Mutex<T>>) {}
+fn test2(foo: Rc<Mutex<MyEnum>>) {}
+fn test3(foo: Rc<Mutex<SubT<usize>>>) {}
 
-pub fn test3(foo: Rc<Mutex<SubT<usize>>>) {}
+// All of these test should be allowed because they are part of the
+// public api and `avoid_breaking_exported_api` is `false` by default.
+pub fn pub_test1<T>(foo: Rc<Mutex<T>>) {}
+pub fn pub_test2(foo: Rc<Mutex<MyEnum>>) {}
+pub fn pub_test3(foo: Rc<Mutex<SubT<usize>>>) {}
 
-fn main() {
-    test1(Rc::new(Mutex::new(1)));
-    test2(Rc::new(Mutex::new(MyEnum::One)));
-    test3(Rc::new(Mutex::new(SubT { foo: 1 })));
-
-    let _my_struct = MyStruct {
-        foo: Rc::new(Mutex::new(1)),
-    };
-}
+fn main() {}
diff --git a/tests/ui/rc_mutex.stderr b/tests/ui/rc_mutex.stderr
index 8e58e2bc2d0..fe84361d781 100644
--- a/tests/ui/rc_mutex.stderr
+++ b/tests/ui/rc_mutex.stderr
@@ -1,28 +1,35 @@
-error: found `Rc<Mutex<_>>`. Consider using `Rc<RefCell<_>>` or `Arc<Mutex<_>>` instead
+error: usage of `Rc<Mutex<_>>`
   --> $DIR/rc_mutex.rs:8:10
    |
 LL |     foo: Rc<Mutex<i32>>,
    |          ^^^^^^^^^^^^^^
    |
    = note: `-D clippy::rc-mutex` implied by `-D warnings`
+   = help: consider using `Rc<RefCell<_>>` or `Arc<Mutex<_>>` instead
 
-error: found `Rc<Mutex<_>>`. Consider using `Rc<RefCell<_>>` or `Arc<Mutex<_>>` instead
-  --> $DIR/rc_mutex.rs:20:22
+error: usage of `Rc<Mutex<_>>`
+  --> $DIR/rc_mutex.rs:26:18
    |
-LL | pub fn test1<T>(foo: Rc<Mutex<T>>) {}
-   |                      ^^^^^^^^^^^^
+LL | fn test1<T>(foo: Rc<Mutex<T>>) {}
+   |                  ^^^^^^^^^^^^
+   |
+   = help: consider using `Rc<RefCell<_>>` or `Arc<Mutex<_>>` instead
 
-error: found `Rc<Mutex<_>>`. Consider using `Rc<RefCell<_>>` or `Arc<Mutex<_>>` instead
-  --> $DIR/rc_mutex.rs:22:19
+error: usage of `Rc<Mutex<_>>`
+  --> $DIR/rc_mutex.rs:27:15
+   |
+LL | fn test2(foo: Rc<Mutex<MyEnum>>) {}
+   |               ^^^^^^^^^^^^^^^^^
    |
-LL | pub fn test2(foo: Rc<Mutex<MyEnum>>) {}
-   |                   ^^^^^^^^^^^^^^^^^
+   = help: consider using `Rc<RefCell<_>>` or `Arc<Mutex<_>>` instead
 
-error: found `Rc<Mutex<_>>`. Consider using `Rc<RefCell<_>>` or `Arc<Mutex<_>>` instead
-  --> $DIR/rc_mutex.rs:24:19
+error: usage of `Rc<Mutex<_>>`
+  --> $DIR/rc_mutex.rs:28:15
+   |
+LL | fn test3(foo: Rc<Mutex<SubT<usize>>>) {}
+   |               ^^^^^^^^^^^^^^^^^^^^^^
    |
-LL | pub fn test3(foo: Rc<Mutex<SubT<usize>>>) {}
-   |                   ^^^^^^^^^^^^^^^^^^^^^^
+   = help: consider using `Rc<RefCell<_>>` or `Arc<Mutex<_>>` instead
 
 error: aborting due to 4 previous errors