Auto merge of #5141 - xiongmao86:issue5095, r=flip1995

Fixes issue 5095

fixes #5095.

- [x] Followed [lint naming conventions][lint_naming]
- [x] Added passing UI tests (including committed `.stderr` file)
- [x] `cargo test` passes locally
- [x] Executed `cargo dev update_lints`
- [x] Added lint documentation
- [x] Run `cargo dev fmt`

[lint_naming]: https://rust-lang.github.io/rfcs/0344-conventions-galore.html#lints

changelog: (internal) warn about collapsible `span_lint_and_then` calls.

clippy_lints/src/as_conversions.rs

@@ -50,6 +50,7 @@ impl EarlyLintPass for AsConversions {
                 AS_CONVERSIONS,
                 expr.span,
                 "using a potentially dangerous silent `as` conversion",
+                None,
                 "consider using a safe wrapper for this conversion",
             );
         }

clippy_lints/src/assertions_on_constants.rs

@@ -41,6 +41,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssertionsOnConstants {
                 } else {
                     "`assert!(true)` will be optimized out by the compiler"
                 },
+                None,
                 "remove it",
             );
         };
@@ -50,6 +51,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssertionsOnConstants {
                 ASSERTIONS_ON_CONSTANTS,
                 e.span,
                 "`assert!(false)` should probably be replaced",
+                None,
                 "use `panic!()` or `unreachable!()`",
             );
         };
@@ -59,6 +61,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssertionsOnConstants {
                 ASSERTIONS_ON_CONSTANTS,
                 e.span,
                 &format!("`assert!(false, {})` should probably be replaced", panic_message),
+                None,
                 &format!("use `panic!({})` or `unreachable!({})`", panic_message, panic_message),
             )
         };

clippy_lints/src/atomic_ordering.rs

@@ -85,6 +85,7 @@ fn check_atomic_load_store(cx: &LateContext<'_, '_>, expr: &Expr<'_>) {
                     INVALID_ATOMIC_ORDERING,
                     ordering_arg.span,
                     "atomic loads cannot have `Release` and `AcqRel` ordering",
+                    None,
                     "consider using ordering modes `Acquire`, `SeqCst` or `Relaxed`"
                 );
             } else if method == "store" &&
@@ -94,6 +95,7 @@ fn check_atomic_load_store(cx: &LateContext<'_, '_>, expr: &Expr<'_>) {
                     INVALID_ATOMIC_ORDERING,
                     ordering_arg.span,
                     "atomic stores cannot have `Acquire` and `AcqRel` ordering",
+                    None,
                     "consider using ordering modes `Release`, `SeqCst` or `Relaxed`"
                 );
             }
@@ -118,6 +120,7 @@ fn check_memory_fence(cx: &LateContext<'_, '_>, expr: &Expr<'_>) {
                 INVALID_ATOMIC_ORDERING,
                 args[0].span,
                 "memory fences cannot have `Relaxed` ordering",
+                None,
                 "consider using ordering modes `Acquire`, `Release`, `AcqRel` or `SeqCst`"
             );
         }

clippy_lints/src/cognitive_complexity.rs

@@ -105,6 +105,7 @@ impl CognitiveComplexity {
                     rust_cc,
                     self.limit.limit()
                 ),
+                None,
                 "you could split it up into multiple smaller functions",
             );
         }

clippy_lints/src/comparison_chain.rs

@@ -104,6 +104,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ComparisonChain {
             COMPARISON_CHAIN,
             expr.span,
             "`if` chain can be rewritten with `match`",
+            None,
             "Consider rewriting the `if` chain to use `cmp` and `match`.",
         )
     }

clippy_lints/src/copies.rs

@@ -183,7 +183,7 @@ fn lint_same_then_else(cx: &LateContext<'_, '_>, blocks: &[&Block<'_>]) {
             IF_SAME_THEN_ELSE,
             j.span,
             "this `if` has identical blocks",
-            i.span,
+            Some(i.span),
             "same as this",
         );
     }
@@ -206,7 +206,7 @@ fn lint_same_cond(cx: &LateContext<'_, '_>, conds: &[&Expr<'_>]) {
             IFS_SAME_COND,
             j.span,
             "this `if` has the same condition as a previous `if`",
-            i.span,
+            Some(i.span),
             "same as this",
         );
     }
@@ -234,7 +234,7 @@ fn lint_same_fns_in_if_cond(cx: &LateContext<'_, '_>, conds: &[&Expr<'_>]) {
             SAME_FUNCTIONS_IN_IF_CONDITION,
             j.span,
             "this `if` has the same function call as a previous `if`",
-            i.span,
+            Some(i.span),
             "same as this",
         );
     }

clippy_lints/src/copy_iterator.rs

@@ -46,7 +46,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for CopyIterator {
                     COPY_ITERATOR,
                     item.span,
                     "you are implementing `Iterator` on a `Copy` type",
-                    item.span,
+                    None,
                     "consider implementing `IntoIterator` instead",
                 );
             }

clippy_lints/src/dbg_macro.rs

@@ -48,6 +48,7 @@ impl EarlyLintPass for DbgMacro {
                     DBG_MACRO,
                     mac.span(),
                     "`dbg!` macro is intended as a debugging tool",
+                    None,
                     "ensure to avoid having uses of it in version control",
                 );
             }

clippy_lints/src/derive.rs

@@ -1,5 +1,5 @@
 use crate::utils::paths;
-use crate::utils::{is_automatically_derived, is_copy, match_path, span_lint_and_then};
+use crate::utils::{is_automatically_derived, is_copy, match_path, span_lint_and_note, span_lint_and_then};
 use if_chain::if_chain;
 use rustc_hir::{Item, ItemKind, TraitRef};
 use rustc_lint::{LateContext, LateLintPass};
@@ -163,14 +163,13 @@ fn check_copy_clone<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, item: &Item<'_>, trait
             _ => (),
         }
 
-        span_lint_and_then(
+        span_lint_and_note(
             cx,
             EXPL_IMPL_CLONE_ON_COPY,
             item.span,
             "you are implementing `Clone` explicitly on a `Copy` type",
-            |diag| {
-                diag.span_note(item.span, "consider deriving `Clone` or removing `Copy`");
-            },
+            Some(item.span),
+            "consider deriving `Clone` or removing `Copy`",
         );
     }
 }

clippy_lints/src/drop_forget_ref.rs

@@ -135,7 +135,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for DropForgetRef {
                                        lint,
                                        expr.span,
                                        &msg,
-                                       arg.span,
+                                       Some(arg.span),
                                        &format!("argument has type `{}`", arg_ty));
                 } else if is_copy(cx, arg_ty) {
                     if match_def_path(cx, def_id, &paths::DROP) {
@@ -151,7 +151,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for DropForgetRef {
                                        lint,
                                        expr.span,
                                        &msg,
-                                       arg.span,
+                                       Some(arg.span),
                                        &format!("argument has type {}", arg_ty));
                 }
             }

clippy_lints/src/else_if_without_else.rs

@@ -61,6 +61,7 @@ impl EarlyLintPass for ElseIfWithoutElse {
                     ELSE_IF_WITHOUT_ELSE,
                     els.span,
                     "`if` expression with an `else if`, but without a final `else`",
+                    None,
                     "add an `else` block here",
                 );
             }

clippy_lints/src/empty_enum.rs

@@ -1,6 +1,6 @@
 //! lint when there is an enum with no variants
 
-use crate::utils::span_lint_and_then;
+use crate::utils::span_lint_and_help;
 use rustc_hir::{Item, ItemKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
@@ -45,13 +45,15 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EmptyEnum {
             let ty = cx.tcx.type_of(did);
             let adt = ty.ty_adt_def().expect("already checked whether this is an enum");
             if adt.variants.is_empty() {
-                span_lint_and_then(cx, EMPTY_ENUM, item.span, "enum with no variants", |diag| {
-                    diag.span_help(
-                        item.span,
-                        "consider using the uninhabited type `!` (never type) or a wrapper \
-                         around it to introduce a type which can't be instantiated",
-                    );
-                });
+                span_lint_and_help(
+                    cx,
+                    EMPTY_ENUM,
+                    item.span,
+                    "enum with no variants",
+                    None,
+                    "consider using the uninhabited type `!` (never type) or a wrapper \
+                    around it to introduce a type which can't be instantiated",
+                );
             }
         }
     }

clippy_lints/src/enum_variants.rs

@@ -206,6 +206,7 @@ fn check_variant(
         lint,
         span,
         &format!("All variants have the same {}fix: `{}`", what, value),
+        None,
         &format!(
             "remove the {}fixes and use full paths to \
              the variants instead of glob imports",

clippy_lints/src/eta_reduction.rs

@@ -7,7 +7,8 @@ use rustc_middle::ty::{self, Ty};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
 use crate::utils::{
-    implements_trait, is_adjusted, iter_input_pats, snippet_opt, span_lint_and_then, type_is_unsafe_function,
+    implements_trait, is_adjusted, iter_input_pats, snippet_opt, span_lint_and_sugg, span_lint_and_then,
+    type_is_unsafe_function,
 };
 
 declare_clippy_lint! {
@@ -131,14 +132,15 @@ fn check_closure(cx: &LateContext<'_, '_>, expr: &Expr<'_>) {
             if let Some(name) = get_ufcs_type_name(cx, method_def_id, &args[0]);
 
             then {
-                span_lint_and_then(cx, REDUNDANT_CLOSURE_FOR_METHOD_CALLS, expr.span, "redundant closure found", |diag| {
-                    diag.span_suggestion(
-                        expr.span,
-                        "remove closure as shown",
-                        format!("{}::{}", name, path.ident.name),
-                        Applicability::MachineApplicable,
-                    );
-                });
+                span_lint_and_sugg(
+                    cx,
+                    REDUNDANT_CLOSURE_FOR_METHOD_CALLS,
+                    expr.span,
+                    "redundant closure found",
+                    "remove closure as shown",
+                    format!("{}::{}", name, path.ident.name),
+                    Applicability::MachineApplicable,
+                );
             }
         );
     }

clippy_lints/src/eval_order_dependence.rs

@@ -310,7 +310,7 @@ impl<'a, 'tcx> Visitor<'tcx> for ReadVisitor<'a, 'tcx> {
                             EVAL_ORDER_DEPENDENCE,
                             expr.span,
                             "unsequenced read of a variable",
-                            self.write_expr.span,
+                            Some(self.write_expr.span),
                             "whether read occurs before this write depends on evaluation order"
                         );
                     }

clippy_lints/src/excessive_bools.rs

@@ -114,6 +114,7 @@ impl ExcessiveBools {
                 FN_PARAMS_EXCESSIVE_BOOLS,
                 span,
                 &format!("more than {} bools in function parameters", self.max_fn_params_bools),
+                None,
                 "consider refactoring bools into two-variant enums",
             );
         }
@@ -153,6 +154,7 @@ impl EarlyLintPass for ExcessiveBools {
                         STRUCT_EXCESSIVE_BOOLS,
                         item.span,
                         &format!("more than {} bools in a struct", self.max_struct_bools),
+                        None,
                         "consider using a state machine or refactoring bools into two-variant enums",
                     );
                 }

clippy_lints/src/formatting.rs

@@ -149,7 +149,7 @@ fn check_assign(cx: &EarlyContext<'_>, expr: &Expr) {
                                  really are doing `.. = ({op} ..)`",
                                 op = op
                             ),
-                            eqop_span,
+                            None,
                             &format!("to remove this lint, use either `{op}=` or `= {op}`", op = op),
                         );
                     }
@@ -188,6 +188,7 @@ fn check_unop(cx: &EarlyContext<'_>, expr: &Expr) {
                     binop = binop_str,
                     unop = unop_str
                 ),
+                None,
                 &format!(
                     "put a space between `{binop}` and `{unop}` and remove the space after `{unop}`",
                     binop = binop_str,
@@ -226,7 +227,7 @@ fn check_else(cx: &EarlyContext<'_>, expr: &Expr) {
                 SUSPICIOUS_ELSE_FORMATTING,
                 else_span,
                 &format!("this is an `else {}` but the formatting might hide it", else_desc),
-                else_span,
+                None,
                 &format!(
                     "to remove this lint, remove the `else` or remove the new line between \
                      `else` and `{}`",
@@ -265,7 +266,7 @@ fn check_array(cx: &EarlyContext<'_>, expr: &Expr) {
                         POSSIBLE_MISSING_COMMA,
                         lint_span,
                         "possibly missing a comma here",
-                        lint_span,
+                        None,
                         "to remove this lint, add a comma or write the expr in a single line",
                     );
                 }
@@ -296,7 +297,7 @@ fn check_missing_else(cx: &EarlyContext<'_>, first: &Expr, second: &Expr) {
                     SUSPICIOUS_ELSE_FORMATTING,
                     else_span,
                     &format!("this looks like {} but the `else` is missing", looks_like),
-                    else_span,
+                    None,
                     &format!(
                         "to remove this lint, add the missing `else` or add a new line before {}",
                         next_thing,

clippy_lints/src/functions.rs

@@ -431,6 +431,7 @@ fn check_needless_must_use(
             DOUBLE_MUST_USE,
             fn_header_span,
             "this function has an empty `#[must_use]` attribute, but returns a type already marked as `#[must_use]`",
+            None,
             "either add some descriptive text or remove the attribute",
         );
     }

clippy_lints/src/identity_conversion.rs

@@ -1,5 +1,5 @@
 use crate::utils::{
-    match_def_path, match_trait_method, paths, same_tys, snippet, snippet_with_macro_callsite, span_lint_and_then,
+    match_def_path, match_trait_method, paths, same_tys, snippet, snippet_with_macro_callsite, span_lint_and_sugg,
 };
 use rustc_errors::Applicability;
 use rustc_hir::{Expr, ExprKind, HirId, MatchSource};
@@ -58,29 +58,31 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for IdentityConversion {
                     if same_tys(cx, a, b) {
                         let sugg = snippet_with_macro_callsite(cx, args[0].span, "<expr>").to_string();
 
-                        span_lint_and_then(cx, IDENTITY_CONVERSION, e.span, "identical conversion", |diag| {
-                            diag.span_suggestion(
-                                e.span,
-                                "consider removing `.into()`",
-                                sugg,
-                                Applicability::MachineApplicable, // snippet
-                            );
-                        });
+                        span_lint_and_sugg(
+                            cx,
+                            IDENTITY_CONVERSION,
+                            e.span,
+                            "identical conversion",
+                            "consider removing `.into()`",
+                            sugg,
+                            Applicability::MachineApplicable, // snippet
+                        );
                     }
                 }
                 if match_trait_method(cx, e, &paths::INTO_ITERATOR) && &*name.ident.as_str() == "into_iter" {
                     let a = cx.tables.expr_ty(e);
                     let b = cx.tables.expr_ty(&args[0]);
                     if same_tys(cx, a, b) {
                         let sugg = snippet(cx, args[0].span, "<expr>").into_owned();
-                        span_lint_and_then(cx, IDENTITY_CONVERSION, e.span, "identical conversion", |diag| {
-                            diag.span_suggestion(
-                                e.span,
-                                "consider removing `.into_iter()`",
-                                sugg,
-                                Applicability::MachineApplicable, // snippet
-                            );
-                        });
+                        span_lint_and_sugg(
+                            cx,
+                            IDENTITY_CONVERSION,
+                            e.span,
+                            "identical conversion",
+                            "consider removing `.into_iter()`",
+                            sugg,
+                            Applicability::MachineApplicable, // snippet
+                        );
                     }
                 }
             },
@@ -95,14 +97,15 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for IdentityConversion {
                                 let sugg = snippet(cx, args[0].span.source_callsite(), "<expr>").into_owned();
                                 let sugg_msg =
                                     format!("consider removing `{}()`", snippet(cx, path.span, "From::from"));
-                                span_lint_and_then(cx, IDENTITY_CONVERSION, e.span, "identical conversion", |diag| {
-                                    diag.span_suggestion(
-                                        e.span,
-                                        &sugg_msg,
-                                        sugg,
-                                        Applicability::MachineApplicable, // snippet
-                                    );
-                                });
+                                span_lint_and_sugg(
+                                    cx,
+                                    IDENTITY_CONVERSION,
+                                    e.span,
+                                    "identical conversion",
+                                    &sugg_msg,
+                                    sugg,
+                                    Applicability::MachineApplicable, // snippet
+                                );
                             }
                         }
                     }