add impl-ordering-except-fn-names config field for arbitrary_source_item_ordering

CHANGELOG.md

@@ -6425,6 +6425,7 @@ Released 2018-09-13
 [`excessive-nesting-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#excessive-nesting-threshold
 [`future-size-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#future-size-threshold
 [`ignore-interior-mutability`]: https://doc.rust-lang.org/clippy/lint_configuration.html#ignore-interior-mutability
+[`impl-ordering-except-fn-names`]: https://doc.rust-lang.org/clippy/lint_configuration.html#impl-ordering-except-fn-names
 [`large-error-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#large-error-threshold
 [`lint-commented-code`]: https://doc.rust-lang.org/clippy/lint_configuration.html#lint-commented-code
 [`literal-representation-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#literal-representation-threshold

book/src/lint_configuration.md

@@ -630,6 +630,16 @@ A list of paths to types that should be treated as if they do not contain interi
 * [`mutable_key_type`](https://rust-lang.github.io/rust-clippy/master/index.html#mutable_key_type)
 
 
+## `impl-ordering-except-fn-names`
+A list of function names that should be ignored when ordering functions in impl blocks.
+
+**Default Value:** `[]`
+
+---
+**Affected lints:**
+* [`arbitrary_source_item_ordering`](https://rust-lang.github.io/rust-clippy/master/index.html#arbitrary_source_item_ordering)
+
+
 ## `large-error-threshold`
 The maximum size of the `Err`-variant in a `Result` returned from a function
 

clippy_config/src/conf.rs

@@ -635,6 +635,9 @@ define_Conf! {
     /// A list of paths to types that should be treated as if they do not contain interior mutability
     #[lints(borrow_interior_mutable_const, declare_interior_mutable_const, ifs_same_cond, mutable_key_type)]
     ignore_interior_mutability: Vec<String> = Vec::from(["bytes::Bytes".into()]),
+    /// A list of function names that should be ignored when ordering functions in impl blocks.
+    #[lints(arbitrary_source_item_ordering)]
+    impl_ordering_except_fn_names: Vec<String> = Vec::new(),
     /// The maximum size of the `Err`-variant in a `Result` returned from a function
     #[lints(result_large_err)]
     large_error_threshold: u64 = 128,

clippy_lints/src/arbitrary_source_item_ordering.rs

@@ -85,6 +85,15 @@ declare_clippy_lint! {
     /// module-items-ordered-within-groupings = ["UPPER_SNAKE_CASE"]
     /// ```
     ///
+    /// #### Exception function names in impl blocks
+    ///
+    /// Sometimes you want to exclude some functions in impl blocks from being linted.
+    /// You can do this by adding the function names in the config.
+    ///
+    /// ```toml
+    /// impl-ordering-except-fn-names = ["new"]
+    /// ```
+    ///
     /// ### Known Problems
     ///
     /// #### Performance Impact
@@ -169,6 +178,7 @@ pub struct ArbitrarySourceItemOrdering {
     enable_ordering_for_trait: bool,
     module_item_order_groupings: SourceItemOrderingModuleItemGroupings,
     module_items_ordered_within_groupings: SourceItemOrderingWithinModuleItemGroupings,
+    impl_ordering_except_fn_names: Vec<String>,
 }
 
 impl ArbitrarySourceItemOrdering {
@@ -184,6 +194,7 @@ impl ArbitrarySourceItemOrdering {
             enable_ordering_for_trait: conf.source_item_ordering.contains(&Trait),
             module_item_order_groupings: conf.module_item_order_groupings.clone(),
             module_items_ordered_within_groupings: conf.module_items_ordered_within_groupings.clone(),
+            impl_ordering_except_fn_names: conf.impl_ordering_except_fn_names.clone(),
         }
     }
 
@@ -321,6 +332,15 @@ impl<'tcx> LateLintPass<'tcx> for ArbitrarySourceItemOrdering {
                     if item.span.in_external_macro(cx.sess().source_map()) {
                         continue;
                     }
+                    // If there are exception function names, skip it.
+                    if !self.impl_ordering_except_fn_names.is_empty()
+                        && convert_assoc_item_kind(item.kind) == SourceItemOrderingTraitAssocItemKind::Fn
+                        && self
+                            .impl_ordering_except_fn_names
+                            .contains(&item.ident.name.to_string())
+                    {
+                        continue;
+                    }
 
                     if let Some(cur_t) = cur_t {
                         let cur_t_kind = convert_assoc_item_kind(cur_t.kind);

tests/ui-toml/arbitrary_source_item_ordering/exceptions/clippy.toml

@@ -0,0 +1 @@
+impl-ordering-except-fn-names = ["new"]

tests/ui-toml/arbitrary_source_item_ordering/ordering_exceptions.exceptions.stderr

@@ -0,0 +1,40 @@
+error: incorrect ordering of items (must be alphabetically ordered)
+  --> tests/ui-toml/arbitrary_source_item_ordering/ordering_exceptions.rs:35:8
+   |
+LL |     fn a() {}
+   |        ^
+   |
+note: should be placed before `b`
+  --> tests/ui-toml/arbitrary_source_item_ordering/ordering_exceptions.rs:31:8
+   |
+LL |     fn b() {}
+   |        ^
+   = note: `-D clippy::arbitrary-source-item-ordering` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::arbitrary_source_item_ordering)]`
+
+error: incorrect ordering of items (must be alphabetically ordered)
+  --> tests/ui-toml/arbitrary_source_item_ordering/ordering_exceptions.rs:47:8
+   |
+LL |     fn b() {}
+   |        ^
+   |
+note: should be placed before `c`
+  --> tests/ui-toml/arbitrary_source_item_ordering/ordering_exceptions.rs:46:8
+   |
+LL |     fn c() {}
+   |        ^
+
+error: incorrect ordering of items (must be alphabetically ordered)
+  --> tests/ui-toml/arbitrary_source_item_ordering/ordering_exceptions.rs:59:8
+   |
+LL |     fn a() {}
+   |        ^
+   |
+note: should be placed before `c`
+  --> tests/ui-toml/arbitrary_source_item_ordering/ordering_exceptions.rs:58:8
+   |
+LL |     fn c() {}
+   |        ^
+
+error: aborting due to 3 previous errors
+

tests/ui-toml/arbitrary_source_item_ordering/ordering_exceptions.rs

@@ -0,0 +1,65 @@
+//@aux-build:../../ui/auxiliary/proc_macros.rs
+//@revisions: exceptions
+//@[exceptions] rustc-env:CLIPPY_CONF_DIR=tests/ui-toml/arbitrary_source_item_ordering/exceptions
+
+#![allow(dead_code)]
+#![warn(clippy::arbitrary_source_item_ordering)]
+
+struct BasicStruct1 {}
+
+impl BasicStruct1 {
+    fn new() -> Self {
+        Self {}
+    }
+    fn a() {}
+    fn b() {}
+}
+
+struct BasicStruct2 {}
+
+impl BasicStruct2 {
+    fn a() {}
+    fn new() -> Self {
+        Self {}
+    }
+    fn b() {}
+}
+
+struct BasicStruct3 {}
+
+impl BasicStruct3 {
+    fn b() {}
+    fn new() -> Self {
+        Self {}
+    }
+    fn a() {}
+    //~^ arbitrary_source_item_ordering
+}
+
+struct BasicStruct4 {}
+
+impl BasicStruct4 {
+    fn a() {}
+    fn new() -> Self {
+        Self {}
+    }
+    fn c() {}
+    fn b() {}
+    //~^ arbitrary_source_item_ordering
+}
+
+struct BasicStruct5 {}
+
+impl BasicStruct5 {
+    fn new() -> Self {
+        Self {}
+    }
+    fn b() {}
+    fn c() {}
+    fn a() {}
+    //~^ arbitrary_source_item_ordering
+}
+
+fn main() {
+    // test code goes here
+}

tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr

@@ -47,6 +47,7 @@ error: error reading Clippy's configuration file: unknown field `foobar`, expect
            excessive-nesting-threshold
            future-size-threshold
            ignore-interior-mutability
+           impl-ordering-except-fn-names
            large-error-threshold
            lint-commented-code
            literal-representation-threshold
@@ -140,6 +141,7 @@ error: error reading Clippy's configuration file: unknown field `barfoo`, expect
            excessive-nesting-threshold
            future-size-threshold
            ignore-interior-mutability
+           impl-ordering-except-fn-names
            large-error-threshold
            lint-commented-code
            literal-representation-threshold
@@ -233,6 +235,7 @@ error: error reading Clippy's configuration file: unknown field `allow_mixed_uni
            excessive-nesting-threshold
            future-size-threshold
            ignore-interior-mutability
+           impl-ordering-except-fn-names
            large-error-threshold
            lint-commented-code
            literal-representation-threshold