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fix rust-lang#3028.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,126 @@ | ||
| use crate::consts::{miri_to_const, Constant}; | ||
| use crate::utils::{in_macro, is_type_diagnostic_item, snippet, span_lint_and_sugg, walk_ptrs_ty}; | ||
| use if_chain::if_chain; | ||
| use rustc_ast::ast::LitKind; | ||
| use rustc_errors::Applicability; | ||
| use rustc_hir::def::{DefKind, Res}; | ||
| use rustc_hir::{Expr, ExprKind}; | ||
| use rustc_lint::{LateContext, LateLintPass}; | ||
| use rustc_middle::ty::{self, Ty}; | ||
| use rustc_session::{declare_lint_pass, declare_tool_lint}; | ||
|
|
||
| declare_clippy_lint! { | ||
| /// **What it does:** Checks for usage of `.repeat(1)` and suggest the following method for each types. | ||
| /// - `.to_string()` for `str` | ||
| /// - `.clone()` for `String` | ||
| /// - `.to_vec()` for `slice` | ||
| /// | ||
| /// **Why is this bad?** For example, `String.repeat(1)` is equivalent to `.clone()`. If cloning the string is the intention behind thi, `clone()` should be used. | ||
| /// | ||
| /// **Known problems:** None. | ||
| /// | ||
| /// **Example:** | ||
| /// | ||
| /// ```rust | ||
| /// fn main() { | ||
| /// let x = String::from("hello world").repeat(1); | ||
| /// } | ||
| /// ``` | ||
| /// Use instead: | ||
| /// ```rust | ||
| /// fn main() { | ||
| /// let x = String::from("hello world").clone(); | ||
| /// } | ||
| /// ``` | ||
| pub REPEAT_ONCE, | ||
| complexity, | ||
| "using `.repeat(1)` instead of `String.clone()`, `str.to_string()` or `slice.to_vec()` " | ||
| } | ||
|
|
||
| declare_lint_pass!(RepeatOnce => [REPEAT_ONCE]); | ||
|
|
||
| impl<'tcx> LateLintPass<'tcx> for RepeatOnce { | ||
| fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'tcx Expr<'_>) { | ||
| if_chain! { | ||
| if let ExprKind::MethodCall(ref path, _, ref args, _) = expr.kind; | ||
| if path.ident.name == sym!(repeat); | ||
| if is_once(cx, &args[1]) && !in_macro(args[0].span); | ||
| then { | ||
| let ty = walk_ptrs_ty(cx.tables().expr_ty(&args[0])); | ||
| if is_str(ty){ | ||
| span_lint_and_sugg( | ||
| cx, | ||
| REPEAT_ONCE, | ||
| expr.span, | ||
| "calling `repeat(1)` on str", | ||
| "consider using `.to_string()` instead", | ||
| format!("{}.to_string()", snippet(cx, args[0].span, r#""...""#)), | ||
| Applicability::MachineApplicable, | ||
| ); | ||
| } else if is_slice(ty) { | ||
| span_lint_and_sugg( | ||
| cx, | ||
| REPEAT_ONCE, | ||
| expr.span, | ||
| "calling `repeat(1)` on slice", | ||
| "consider using `.to_vec()` instead", | ||
| format!("{}.to_vec()", snippet(cx, args[0].span, r#""...""#)), | ||
| Applicability::MachineApplicable, | ||
| ); | ||
| } else if is_type_diagnostic_item(cx, ty, sym!(string_type)) { | ||
| span_lint_and_sugg( | ||
| cx, | ||
| REPEAT_ONCE, | ||
| expr.span, | ||
| "calling `repeat(1)` on a string literal", | ||
| "consider using `.clone()` instead", | ||
| format!("{}.clone()", snippet(cx, args[0].span, r#""...""#)), | ||
| Applicability::MachineApplicable, | ||
| ); | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| fn is_once<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'_>) -> bool { | ||
| match expr.kind { | ||
| ExprKind::Lit(ref lit) => { | ||
| if let LitKind::Int(ref lit_content, _) = lit.node { | ||
| *lit_content == 1 | ||
| } else { | ||
| false | ||
| } | ||
| }, | ||
| ExprKind::Path(rustc_hir::QPath::Resolved(None, path)) => { | ||
| if let Res::Def(DefKind::Const, def_id) = path.res { | ||
| let ty = cx.tcx.type_of(def_id); | ||
| let con = cx | ||
| .tcx | ||
| .const_eval_poly(def_id) | ||
| .ok() | ||
| .map(|val| rustc_middle::ty::Const::from_value(cx.tcx, val, ty)) | ||
| .unwrap(); | ||
| let con = miri_to_const(con); | ||
| con == Some(Constant::Int(1)) | ||
| } else { | ||
| false | ||
| } | ||
| }, | ||
| _ => false, | ||
| } | ||
| } | ||
|
|
||
| fn is_str(ty: Ty<'_>) -> bool { | ||
| match ty.kind { | ||
| ty::Str => true, | ||
| _ => false, | ||
| } | ||
| } | ||
|
|
||
| fn is_slice(ty: Ty<'_>) -> bool { | ||
| match ty.kind { | ||
| ty::Slice(..) | ty::Array(..) => true, | ||
| _ => false, | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,16 @@ | ||
| // run-rustfix | ||
| #![warn(clippy::repeat_once)] | ||
| #[allow(unused, clippy::many_single_char_names, clippy::redundant_clone)] | ||
| fn main() { | ||
| const N: usize = 1; | ||
| let s = "str"; | ||
| let string = "String".to_string(); | ||
| let slice = [1; 5]; | ||
|
|
||
| let a = [1; 5].to_vec(); | ||
| let b = slice.to_vec(); | ||
| let c = "hello".to_string(); | ||
| let d = "hi".to_string(); | ||
| let e = s.to_string(); | ||
| let f = string.clone(); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,16 @@ | ||
| // run-rustfix | ||
| #![warn(clippy::repeat_once)] | ||
| #[allow(unused, clippy::many_single_char_names, clippy::redundant_clone)] | ||
| fn main() { | ||
| const N: usize = 1; | ||
| let s = "str"; | ||
| let string = "String".to_string(); | ||
| let slice = [1; 5]; | ||
|
|
||
| let a = [1; 5].repeat(1); | ||
| let b = slice.repeat(1); | ||
| let c = "hello".repeat(N); | ||
| let d = "hi".repeat(1); | ||
| let e = s.repeat(1); | ||
| let f = string.repeat(1); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,40 @@ | ||
| error: calling `repeat(1)` on slice | ||
| --> $DIR/repeat_once.rs:10:13 | ||
| | | ||
| LL | let a = [1; 5].repeat(1); | ||
| | ^^^^^^^^^^^^^^^^ help: consider using `.to_vec()` instead: `[1; 5].to_vec()` | ||
| | | ||
| = note: `-D clippy::repeat-once` implied by `-D warnings` | ||
|
|
||
| error: calling `repeat(1)` on slice | ||
| --> $DIR/repeat_once.rs:11:13 | ||
| | | ||
| LL | let b = slice.repeat(1); | ||
| | ^^^^^^^^^^^^^^^ help: consider using `.to_vec()` instead: `slice.to_vec()` | ||
|
|
||
| error: calling `repeat(1)` on str | ||
| --> $DIR/repeat_once.rs:12:13 | ||
| | | ||
| LL | let c = "hello".repeat(N); | ||
| | ^^^^^^^^^^^^^^^^^ help: consider using `.to_string()` instead: `"hello".to_string()` | ||
|
|
||
| error: calling `repeat(1)` on str | ||
| --> $DIR/repeat_once.rs:13:13 | ||
| | | ||
| LL | let d = "hi".repeat(1); | ||
| | ^^^^^^^^^^^^^^ help: consider using `.to_string()` instead: `"hi".to_string()` | ||
|
|
||
| error: calling `repeat(1)` on str | ||
| --> $DIR/repeat_once.rs:14:13 | ||
| | | ||
| LL | let e = s.repeat(1); | ||
| | ^^^^^^^^^^^ help: consider using `.to_string()` instead: `s.to_string()` | ||
|
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||
| error: calling `repeat(1)` on a string literal | ||
| --> $DIR/repeat_once.rs:15:13 | ||
| | | ||
| LL | let f = string.repeat(1); | ||
| | ^^^^^^^^^^^^^^^^ help: consider using `.clone()` instead: `string.clone()` | ||
|
|
||
| error: aborting due to 6 previous errors | ||
|
|