diff --git a/CHANGELOG.md b/CHANGELOG.md
index fa4e1e7ac38..edd7bc250a7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3830,6 +3830,7 @@ Released 2018-09-13
[`manual_assert`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_assert
[`manual_async_fn`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_async_fn
[`manual_bits`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_bits
+[`manual_empty_string_creations`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_empty_string_creations
[`manual_filter_map`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_filter_map
[`manual_find`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_find
[`manual_find_map`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_find_map
diff --git a/clippy_dev/src/new_lint.rs b/clippy_dev/src/new_lint.rs
index 10a8f31f457..be05e67d724 100644
--- a/clippy_dev/src/new_lint.rs
+++ b/clippy_dev/src/new_lint.rs
@@ -155,7 +155,7 @@ fn to_camel_case(name: &str) -> String {
name.split('_')
.map(|s| {
if s.is_empty() {
- String::from("")
+ String::new()
} else {
[&s[0..1].to_uppercase(), &s[1..]].concat()
}
diff --git a/clippy_lints/src/lib.register_all.rs b/clippy_lints/src/lib.register_all.rs
index 030da3c3db8..a0a4b07a77e 100644
--- a/clippy_lints/src/lib.register_all.rs
+++ b/clippy_lints/src/lib.register_all.rs
@@ -124,6 +124,7 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![
LintId::of(main_recursion::MAIN_RECURSION),
LintId::of(manual_async_fn::MANUAL_ASYNC_FN),
LintId::of(manual_bits::MANUAL_BITS),
+ LintId::of(manual_empty_string_creations::MANUAL_EMPTY_STRING_CREATIONS),
LintId::of(manual_non_exhaustive::MANUAL_NON_EXHAUSTIVE),
LintId::of(manual_rem_euclid::MANUAL_REM_EUCLID),
LintId::of(manual_retain::MANUAL_RETAIN),
diff --git a/clippy_lints/src/lib.register_lints.rs b/clippy_lints/src/lib.register_lints.rs
index 122b5fe529b..b7dbd30aa0c 100644
--- a/clippy_lints/src/lib.register_lints.rs
+++ b/clippy_lints/src/lib.register_lints.rs
@@ -244,6 +244,7 @@ store.register_lints(&[
manual_assert::MANUAL_ASSERT,
manual_async_fn::MANUAL_ASYNC_FN,
manual_bits::MANUAL_BITS,
+ manual_empty_string_creations::MANUAL_EMPTY_STRING_CREATIONS,
manual_instant_elapsed::MANUAL_INSTANT_ELAPSED,
manual_non_exhaustive::MANUAL_NON_EXHAUSTIVE,
manual_ok_or::MANUAL_OK_OR,
diff --git a/clippy_lints/src/lib.register_style.rs b/clippy_lints/src/lib.register_style.rs
index bfa654238f1..6972c75597a 100644
--- a/clippy_lints/src/lib.register_style.rs
+++ b/clippy_lints/src/lib.register_style.rs
@@ -44,6 +44,7 @@ store.register_group(true, "clippy::style", Some("clippy_style"), vec![
LintId::of(main_recursion::MAIN_RECURSION),
LintId::of(manual_async_fn::MANUAL_ASYNC_FN),
LintId::of(manual_bits::MANUAL_BITS),
+ LintId::of(manual_empty_string_creations::MANUAL_EMPTY_STRING_CREATIONS),
LintId::of(manual_non_exhaustive::MANUAL_NON_EXHAUSTIVE),
LintId::of(map_clone::MAP_CLONE),
LintId::of(match_result_ok::MATCH_RESULT_OK),
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 521739c28ff..a041fbc7fd9 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -273,6 +273,7 @@ mod main_recursion;
mod manual_assert;
mod manual_async_fn;
mod manual_bits;
+mod manual_empty_string_creations;
mod manual_instant_elapsed;
mod manual_non_exhaustive;
mod manual_ok_or;
@@ -933,6 +934,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| Box::new(std_instead_of_core::StdReexports::default()));
store.register_late_pass(|| Box::new(manual_instant_elapsed::ManualInstantElapsed));
store.register_late_pass(|| Box::new(partialeq_to_none::PartialeqToNone));
+ store.register_late_pass(|| Box::new(manual_empty_string_creations::ManualEmptyStringCreations));
// add lints here, do not remove this comment, it's used in `new_lint`
}
diff --git a/clippy_lints/src/manual_async_fn.rs b/clippy_lints/src/manual_async_fn.rs
index a0ca7e6ff1e..2502c8f880d 100644
--- a/clippy_lints/src/manual_async_fn.rs
+++ b/clippy_lints/src/manual_async_fn.rs
@@ -192,7 +192,7 @@ fn suggested_ret(cx: &LateContext<'_>, output: &Ty<'_>) -> Option<(&'static str,
match output.kind {
TyKind::Tup(tys) if tys.is_empty() => {
let sugg = "remove the return type";
- Some((sugg, "".into()))
+ Some((sugg, String::new()))
},
_ => {
let sugg = "return the output of the future directly";
diff --git a/clippy_lints/src/manual_empty_string_creations.rs b/clippy_lints/src/manual_empty_string_creations.rs
new file mode 100644
index 00000000000..dd602a89b4f
--- /dev/null
+++ b/clippy_lints/src/manual_empty_string_creations.rs
@@ -0,0 +1,141 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use rustc_ast::LitKind;
+use rustc_errors::Applicability::MachineApplicable;
+use rustc_hir::{Expr, ExprKind, PathSegment, QPath, TyKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty;
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::{sym, symbol, Span};
+
+declare_clippy_lint! {
+ /// ### What it does
+ ///
+ /// Checks for usage of `""` to create a `String`, such as `"".to_string()`, `"".to_owned()`,
+ /// `String::from("")` and others.
+ ///
+ /// ### Why is this bad?
+ ///
+ /// Different ways of creating an empty string makes your code less standardized, which can
+ /// be confusing.
+ ///
+ /// ### Example
+ /// ```rust
+ /// let a = "".to_string();
+ /// let b: String = "".into();
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// let a = String::new();
+ /// let b = String::new();
+ /// ```
+ #[clippy::version = "1.65.0"]
+ pub MANUAL_EMPTY_STRING_CREATIONS,
+ style,
+ "empty String is being created manually"
+}
+declare_lint_pass!(ManualEmptyStringCreations => [MANUAL_EMPTY_STRING_CREATIONS]);
+
+impl LateLintPass<'_> for ManualEmptyStringCreations {
+ fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
+ if expr.span.from_expansion() {
+ return;
+ }
+
+ let ty = cx.typeck_results().expr_ty(expr);
+ match ty.kind() {
+ ty::Adt(adt_def, _) if adt_def.is_struct() => {
+ if !cx.tcx.is_diagnostic_item(sym::String, adt_def.did()) {
+ return;
+ }
+ },
+ _ => return,
+ }
+
+ match expr.kind {
+ ExprKind::Call(func, args) => {
+ parse_call(cx, expr.span, func, args);
+ },
+ ExprKind::MethodCall(path_segment, args, _) => {
+ parse_method_call(cx, expr.span, path_segment, args);
+ },
+ _ => (),
+ }
+ }
+}
+
+/// Checks if an expression's kind corresponds to an empty &str.
+fn is_expr_kind_empty_str(expr_kind: &ExprKind<'_>) -> bool {
+ if let ExprKind::Lit(lit) = expr_kind &&
+ let LitKind::Str(value, _) = lit.node &&
+ value == symbol::kw::Empty
+ {
+ return true;
+ }
+
+ false
+}
+
+/// Emits the `MANUAL_EMPTY_STRING_CREATION` warning and suggests the appropriate fix.
+fn warn_then_suggest(cx: &LateContext<'_>, span: Span) {
+ span_lint_and_sugg(
+ cx,
+ MANUAL_EMPTY_STRING_CREATIONS,
+ span,
+ "empty String is being created manually",
+ "consider using",
+ "String::new()".into(),
+ MachineApplicable,
+ );
+}
+
+/// Tries to parse an expression as a method call, emiting the warning if necessary.
+fn parse_method_call(cx: &LateContext<'_>, span: Span, path_segment: &PathSegment<'_>, args: &[Expr<'_>]) {
+ if args.is_empty() {
+ // When parsing TryFrom::try_from(...).expect(...), we will have more than 1 arg.
+ return;
+ }
+
+ let ident = path_segment.ident.as_str();
+ let method_arg_kind = &args[0].kind;
+ if ["to_string", "to_owned", "into"].contains(&ident) && is_expr_kind_empty_str(method_arg_kind) {
+ warn_then_suggest(cx, span);
+ } else if let ExprKind::Call(func, args) = method_arg_kind {
+ // If our first argument is a function call itself, it could be an `unwrap`-like function.
+ // E.g. String::try_from("hello").unwrap(), TryFrom::try_from("").expect("hello"), etc.
+ parse_call(cx, span, func, args);
+ }
+}
+
+/// Tries to parse an expression as a function call, emiting the warning if necessary.
+fn parse_call(cx: &LateContext<'_>, span: Span, func: &Expr<'_>, args: &[Expr<'_>]) {
+ if args.len() != 1 {
+ return;
+ }
+
+ let arg_kind = &args[0].kind;
+ if let ExprKind::Path(qpath) = &func.kind {
+ if let QPath::TypeRelative(_, _) = qpath {
+ // String::from(...) or String::try_from(...)
+ if let QPath::TypeRelative(ty, path_seg) = qpath &&
+ [sym::from, sym::try_from].contains(&path_seg.ident.name) &&
+ let TyKind::Path(qpath) = &ty.kind &&
+ let QPath::Resolved(_, path) = qpath &&
+ let [path_seg] = path.segments &&
+ path_seg.ident.name == sym::String &&
+ is_expr_kind_empty_str(arg_kind)
+ {
+ warn_then_suggest(cx, span);
+ }
+ } else if let QPath::Resolved(_, path) = qpath {
+ // From::from(...) or TryFrom::try_from(...)
+ if let [path_seg1, path_seg2] = path.segments &&
+ is_expr_kind_empty_str(arg_kind) && (
+ (path_seg1.ident.name == sym::From && path_seg2.ident.name == sym::from) ||
+ (path_seg1.ident.name == sym::TryFrom && path_seg2.ident.name == sym::try_from)
+ )
+ {
+ warn_then_suggest(cx, span);
+ }
+ }
+ }
+}
diff --git a/clippy_lints/src/methods/option_map_unwrap_or.rs b/clippy_lints/src/methods/option_map_unwrap_or.rs
index 6c641af59f9..3c4002a3aef 100644
--- a/clippy_lints/src/methods/option_map_unwrap_or.rs
+++ b/clippy_lints/src/methods/option_map_unwrap_or.rs
@@ -78,7 +78,7 @@ pub(super) fn check<'tcx>(
map_span,
String::from(if unwrap_snippet_none { "and_then" } else { "map_or" }),
),
- (expr.span.with_lo(unwrap_recv.span.hi()), String::from("")),
+ (expr.span.with_lo(unwrap_recv.span.hi()), String::new()),
];
if !unwrap_snippet_none {
diff --git a/clippy_lints/src/misc_early/unneeded_wildcard_pattern.rs b/clippy_lints/src/misc_early/unneeded_wildcard_pattern.rs
index df044538fe1..7c4ae746e90 100644
--- a/clippy_lints/src/misc_early/unneeded_wildcard_pattern.rs
+++ b/clippy_lints/src/misc_early/unneeded_wildcard_pattern.rs
@@ -46,7 +46,7 @@ fn span_lint(cx: &EarlyContext<'_>, span: Span, only_one: bool) {
"these patterns are unneeded as the `..` pattern can match those elements"
},
if only_one { "remove it" } else { "remove them" },
- "".to_string(),
+ String::new(),
Applicability::MachineApplicable,
);
}
diff --git a/clippy_lints/src/unnecessary_wraps.rs b/clippy_lints/src/unnecessary_wraps.rs
index f4f5a4336a3..a5afbb8ff9d 100644
--- a/clippy_lints/src/unnecessary_wraps.rs
+++ b/clippy_lints/src/unnecessary_wraps.rs
@@ -130,7 +130,7 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryWraps {
(
ret_expr.span,
if inner_type.is_unit() {
- "".to_string()
+ String::new()
} else {
snippet(cx, arg.span.source_callsite(), "..").to_string()
}
diff --git a/clippy_utils/src/msrvs.rs b/clippy_utils/src/msrvs.rs
index 7fa0046a267..62020e21c81 100644
--- a/clippy_utils/src/msrvs.rs
+++ b/clippy_utils/src/msrvs.rs
@@ -32,8 +32,8 @@ msrv_aliases! {
1,30,0 { ITERATOR_FIND_MAP, TOOL_ATTRIBUTES }
1,28,0 { FROM_BOOL }
1,26,0 { RANGE_INCLUSIVE, STRING_RETAIN }
+ 1,24,0 { IS_ASCII_DIGIT }
1,18,0 { HASH_MAP_RETAIN, HASH_SET_RETAIN }
1,17,0 { FIELD_INIT_SHORTHAND, STATIC_IN_CONST, EXPECT_ERR }
1,16,0 { STR_REPEAT }
- 1,24,0 { IS_ASCII_DIGIT }
}
diff --git a/tests/ui/case_sensitive_file_extension_comparisons.rs b/tests/ui/case_sensitive_file_extension_comparisons.rs
index 0d65071af15..6f0485b5279 100644
--- a/tests/ui/case_sensitive_file_extension_comparisons.rs
+++ b/tests/ui/case_sensitive_file_extension_comparisons.rs
@@ -14,31 +14,31 @@ fn is_rust_file(filename: &str) -> bool {
fn main() {
// std::string::String and &str should trigger the lint failure with .ext12
- let _ = String::from("").ends_with(".ext12");
+ let _ = String::new().ends_with(".ext12");
let _ = "str".ends_with(".ext12");
// The test struct should not trigger the lint failure with .ext12
TestStruct {}.ends_with(".ext12");
// std::string::String and &str should trigger the lint failure with .EXT12
- let _ = String::from("").ends_with(".EXT12");
+ let _ = String::new().ends_with(".EXT12");
let _ = "str".ends_with(".EXT12");
// The test struct should not trigger the lint failure with .EXT12
TestStruct {}.ends_with(".EXT12");
// Should not trigger the lint failure with .eXT12
- let _ = String::from("").ends_with(".eXT12");
+ let _ = String::new().ends_with(".eXT12");
let _ = "str".ends_with(".eXT12");
TestStruct {}.ends_with(".eXT12");
// Should not trigger the lint failure with .EXT123 (too long)
- let _ = String::from("").ends_with(".EXT123");
+ let _ = String::new().ends_with(".EXT123");
let _ = "str".ends_with(".EXT123");
TestStruct {}.ends_with(".EXT123");
// Shouldn't fail if it doesn't start with a dot
- let _ = String::from("").ends_with("a.ext");
+ let _ = String::new().ends_with("a.ext");
let _ = "str".ends_with("a.extA");
TestStruct {}.ends_with("a.ext");
}
diff --git a/tests/ui/case_sensitive_file_extension_comparisons.stderr b/tests/ui/case_sensitive_file_extension_comparisons.stderr
index 05b98169f2d..5d9a043edb9 100644
--- a/tests/ui/case_sensitive_file_extension_comparisons.stderr
+++ b/tests/ui/case_sensitive_file_extension_comparisons.stderr
@@ -8,10 +8,10 @@ LL | filename.ends_with(".rs")
= help: consider using a case-insensitive comparison instead
error: case-sensitive file extension comparison
- --> $DIR/case_sensitive_file_extension_comparisons.rs:17:30
+ --> $DIR/case_sensitive_file_extension_comparisons.rs:17:27
|
-LL | let _ = String::from("").ends_with(".ext12");
- | ^^^^^^^^^^^^^^^^^^^
+LL | let _ = String::new().ends_with(".ext12");
+ | ^^^^^^^^^^^^^^^^^^^
|
= help: consider using a case-insensitive comparison instead
@@ -24,10 +24,10 @@ LL | let _ = "str".ends_with(".ext12");
= help: consider using a case-insensitive comparison instead
error: case-sensitive file extension comparison
- --> $DIR/case_sensitive_file_extension_comparisons.rs:24:30
+ --> $DIR/case_sensitive_file_extension_comparisons.rs:24:27
|
-LL | let _ = String::from("").ends_with(".EXT12");
- | ^^^^^^^^^^^^^^^^^^^
+LL | let _ = String::new().ends_with(".EXT12");
+ | ^^^^^^^^^^^^^^^^^^^
|
= help: consider using a case-insensitive comparison instead
diff --git a/tests/ui/format.fixed b/tests/ui/format.fixed
index 6b754f3bd71..b56d6aec508 100644
--- a/tests/ui/format.fixed
+++ b/tests/ui/format.fixed
@@ -33,7 +33,7 @@ fn main() {
format!("foo {}", "bar");
format!("{} bar", "foo");
- let arg: String = "".to_owned();
+ let arg = String::new();
arg.to_string();
format!("{:?}", arg); // Don't warn about debug.
format!("{:8}", arg);
diff --git a/tests/ui/format.rs b/tests/ui/format.rs
index ca9826b356e..4c1a3a840ed 100644
--- a/tests/ui/format.rs
+++ b/tests/ui/format.rs
@@ -35,7 +35,7 @@ fn main() {
format!("foo {}", "bar");
format!("{} bar", "foo");
- let arg: String = "".to_owned();
+ let arg = String::new();
format!("{}", arg);
format!("{:?}", arg); // Don't warn about debug.
format!("{:8}", arg);
diff --git a/tests/ui/identity_op.fixed b/tests/ui/identity_op.fixed
index 5f9cebe212a..fa564e23cd2 100644
--- a/tests/ui/identity_op.fixed
+++ b/tests/ui/identity_op.fixed
@@ -68,7 +68,7 @@ fn main() {
&x;
x;
- let mut a = A("".into());
+ let mut a = A(String::new());
let b = a << 0; // no error: non-integer
1 * Meter; // no error: non-integer
diff --git a/tests/ui/identity_op.rs b/tests/ui/identity_op.rs
index ca799c9cfac..3d06d2a73b6 100644
--- a/tests/ui/identity_op.rs
+++ b/tests/ui/identity_op.rs
@@ -68,7 +68,7 @@ fn main() {
&x >> 0;
x >> &0;
- let mut a = A("".into());
+ let mut a = A(String::new());
let b = a << 0; // no error: non-integer
1 * Meter; // no error: non-integer
diff --git a/tests/ui/manual_empty_string_creations.fixed b/tests/ui/manual_empty_string_creations.fixed
new file mode 100644
index 00000000000..caf0c657c81
--- /dev/null
+++ b/tests/ui/manual_empty_string_creations.fixed
@@ -0,0 +1,63 @@
+// run-rustfix
+
+#![warn(clippy::manual_empty_string_creations)]
+
+macro_rules! create_strings_from_macro {
+ // When inside a macro, nothing should warn to prevent false positives.
+ ($some_str:expr) => {
+ let _: String = $some_str.into();
+ let _ = $some_str.to_string();
+ };
+}
+
+fn main() {
+ // Method calls
+ let _ = String::new();
+ let _ = "no warning".to_string();
+
+ let _ = String::new();
+ let _ = "no warning".to_owned();
+
+ let _: String = String::new();
+ let _: String = "no warning".into();
+
+ let _: SomeOtherStruct = "no warning".into();
+ let _: SomeOtherStruct = "".into(); // No warning too. We are not converting into String.
+
+ // Calls
+ let _ = String::new();
+ let _ = String::new();
+ let _ = String::from("no warning");
+ let _ = SomeOtherStruct::from("no warning");
+ let _ = SomeOtherStruct::from(""); // Again: no warning.
+
+ let _ = String::new();
+ let _ = String::try_from("no warning").unwrap();
+ let _ = String::try_from("no warning").expect("this should not warn");
+ let _ = SomeOtherStruct::try_from("no warning").unwrap();
+ let _ = SomeOtherStruct::try_from("").unwrap(); // Again: no warning.
+
+ let _: String = String::new();
+ let _: String = From::from("no warning");
+ let _: SomeOtherStruct = From::from("no warning");
+ let _: SomeOtherStruct = From::from(""); // Again: no warning.
+
+ let _: String = String::new();
+ let _: String = TryFrom::try_from("no warning").unwrap();
+ let _: String = TryFrom::try_from("no warning").expect("this should not warn");
+ let _: String = String::new();
+ let _: SomeOtherStruct = TryFrom::try_from("no_warning").unwrap();
+ let _: SomeOtherStruct = TryFrom::try_from("").unwrap(); // Again: no warning.
+
+ // Macros (never warn)
+ create_strings_from_macro!("");
+ create_strings_from_macro!("Hey");
+}
+
+struct SomeOtherStruct {}
+
+impl From<&str> for SomeOtherStruct {
+ fn from(_value: &str) -> Self {
+ Self {}
+ }
+}
diff --git a/tests/ui/manual_empty_string_creations.rs b/tests/ui/manual_empty_string_creations.rs
new file mode 100644
index 00000000000..ed39a05ed5c
--- /dev/null
+++ b/tests/ui/manual_empty_string_creations.rs
@@ -0,0 +1,63 @@
+// run-rustfix
+
+#![warn(clippy::manual_empty_string_creations)]
+
+macro_rules! create_strings_from_macro {
+ // When inside a macro, nothing should warn to prevent false positives.
+ ($some_str:expr) => {
+ let _: String = $some_str.into();
+ let _ = $some_str.to_string();
+ };
+}
+
+fn main() {
+ // Method calls
+ let _ = "".to_string();
+ let _ = "no warning".to_string();
+
+ let _ = "".to_owned();
+ let _ = "no warning".to_owned();
+
+ let _: String = "".into();
+ let _: String = "no warning".into();
+
+ let _: SomeOtherStruct = "no warning".into();
+ let _: SomeOtherStruct = "".into(); // No warning too. We are not converting into String.
+
+ // Calls
+ let _ = String::from("");
+ let _ = <String>::from("");
+ let _ = String::from("no warning");
+ let _ = SomeOtherStruct::from("no warning");
+ let _ = SomeOtherStruct::from(""); // Again: no warning.
+
+ let _ = String::try_from("").unwrap();
+ let _ = String::try_from("no warning").unwrap();
+ let _ = String::try_from("no warning").expect("this should not warn");
+ let _ = SomeOtherStruct::try_from("no warning").unwrap();
+ let _ = SomeOtherStruct::try_from("").unwrap(); // Again: no warning.
+
+ let _: String = From::from("");
+ let _: String = From::from("no warning");
+ let _: SomeOtherStruct = From::from("no warning");
+ let _: SomeOtherStruct = From::from(""); // Again: no warning.
+
+ let _: String = TryFrom::try_from("").unwrap();
+ let _: String = TryFrom::try_from("no warning").unwrap();
+ let _: String = TryFrom::try_from("no warning").expect("this should not warn");
+ let _: String = TryFrom::try_from("").expect("this should warn");
+ let _: SomeOtherStruct = TryFrom::try_from("no_warning").unwrap();
+ let _: SomeOtherStruct = TryFrom::try_from("").unwrap(); // Again: no warning.
+
+ // Macros (never warn)
+ create_strings_from_macro!("");
+ create_strings_from_macro!("Hey");
+}
+
+struct SomeOtherStruct {}
+
+impl From<&str> for SomeOtherStruct {
+ fn from(_value: &str) -> Self {
+ Self {}
+ }
+}
diff --git a/tests/ui/manual_empty_string_creations.stderr b/tests/ui/manual_empty_string_creations.stderr
new file mode 100644
index 00000000000..f38ba02a508
--- /dev/null
+++ b/tests/ui/manual_empty_string_creations.stderr
@@ -0,0 +1,58 @@
+error: empty String is being created manually
+ --> $DIR/manual_empty_string_creations.rs:15:13
+ |
+LL | let _ = "".to_string();
+ | ^^^^^^^^^^^^^^ help: consider using: `String::new()`
+ |
+ = note: `-D clippy::manual-empty-string-creations` implied by `-D warnings`
+
+error: empty String is being created manually
+ --> $DIR/manual_empty_string_creations.rs:18:13
+ |
+LL | let _ = "".to_owned();
+ | ^^^^^^^^^^^^^ help: consider using: `String::new()`
+
+error: empty String is being created manually
+ --> $DIR/manual_empty_string_creations.rs:21:21
+ |
+LL | let _: String = "".into();
+ | ^^^^^^^^^ help: consider using: `String::new()`
+
+error: empty String is being created manually
+ --> $DIR/manual_empty_string_creations.rs:28:13
+ |
+LL | let _ = String::from("");
+ | ^^^^^^^^^^^^^^^^ help: consider using: `String::new()`
+
+error: empty String is being created manually
+ --> $DIR/manual_empty_string_creations.rs:29:13
+ |
+LL | let _ = <String>::from("");
+ | ^^^^^^^^^^^^^^^^^^ help: consider using: `String::new()`
+
+error: empty String is being created manually
+ --> $DIR/manual_empty_string_creations.rs:34:13
+ |
+LL | let _ = String::try_from("").unwrap();
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `String::new()`
+
+error: empty String is being created manually
+ --> $DIR/manual_empty_string_creations.rs:40:21
+ |
+LL | let _: String = From::from("");
+ | ^^^^^^^^^^^^^^ help: consider using: `String::new()`
+
+error: empty String is being created manually
+ --> $DIR/manual_empty_string_creations.rs:45:21
+ |
+LL | let _: String = TryFrom::try_from("").unwrap();
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `String::new()`
+
+error: empty String is being created manually
+ --> $DIR/manual_empty_string_creations.rs:48:21
+ |
+LL | let _: String = TryFrom::try_from("").expect("this should warn");
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `String::new()`
+
+error: aborting due to 9 previous errors
+
diff --git a/tests/ui/or_fun_call.fixed b/tests/ui/or_fun_call.fixed
index fdb08d953ff..18ea4e55029 100644
--- a/tests/ui/or_fun_call.fixed
+++ b/tests/ui/or_fun_call.fixed
@@ -90,8 +90,8 @@ fn or_fun_call() {
let mut btree_vec = BTreeMap::<u64, Vec<i32>>::new();
btree_vec.entry(42).or_insert(vec![]);
- let stringy = Some(String::from(""));
- let _ = stringy.unwrap_or_else(|| "".to_owned());
+ let stringy = Some(String::new());
+ let _ = stringy.unwrap_or_default();
let opt = Some(1);
let hello = "Hello";
diff --git a/tests/ui/or_fun_call.rs b/tests/ui/or_fun_call.rs
index 57ab5f03ee2..c353b41e449 100644
--- a/tests/ui/or_fun_call.rs
+++ b/tests/ui/or_fun_call.rs
@@ -90,8 +90,8 @@ fn or_fun_call() {
let mut btree_vec = BTreeMap::<u64, Vec<i32>>::new();
btree_vec.entry(42).or_insert(vec![]);
- let stringy = Some(String::from(""));
- let _ = stringy.unwrap_or("".to_owned());
+ let stringy = Some(String::new());
+ let _ = stringy.unwrap_or(String::new());
let opt = Some(1);
let hello = "Hello";
diff --git a/tests/ui/or_fun_call.stderr b/tests/ui/or_fun_call.stderr
index 4c5938ab88b..887f23ac976 100644
--- a/tests/ui/or_fun_call.stderr
+++ b/tests/ui/or_fun_call.stderr
@@ -66,11 +66,11 @@ error: use of `unwrap_or` followed by a function call
LL | without_default.unwrap_or(Foo::new());
| ^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(Foo::new)`
-error: use of `unwrap_or` followed by a function call
+error: use of `unwrap_or` followed by a call to `new`
--> $DIR/or_fun_call.rs:94:21
|
-LL | let _ = stringy.unwrap_or("".to_owned());
- | ^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| "".to_owned())`
+LL | let _ = stringy.unwrap_or(String::new());
+ | ^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_default()`
error: use of `unwrap_or` followed by a function call
--> $DIR/or_fun_call.rs:102:21
diff --git a/tests/ui/string_add.rs b/tests/ui/string_add.rs
index 30fd17c59e5..16673c01e63 100644
--- a/tests/ui/string_add.rs
+++ b/tests/ui/string_add.rs
@@ -7,13 +7,13 @@ extern crate macro_rules;
#[allow(clippy::string_add_assign, unused)]
fn main() {
// ignores assignment distinction
- let mut x = "".to_owned();
+ let mut x = String::new();
for _ in 1..3 {
x = x + ".";
}
- let y = "".to_owned();
+ let y = String::new();
let z = y + "...";
assert_eq!(&x, &z);
diff --git a/tests/ui/string_add_assign.fixed b/tests/ui/string_add_assign.fixed
index db71bab1e52..b687f43b254 100644
--- a/tests/ui/string_add_assign.fixed
+++ b/tests/ui/string_add_assign.fixed
@@ -4,13 +4,13 @@
#[warn(clippy::string_add_assign)]
fn main() {
// ignores assignment distinction
- let mut x = "".to_owned();
+ let mut x = String::new();
for _ in 1..3 {
x += ".";
}
- let y = "".to_owned();
+ let y = String::new();
let z = y + "...";
assert_eq!(&x, &z);
diff --git a/tests/ui/string_add_assign.rs b/tests/ui/string_add_assign.rs
index 644991945cb..e5dbde108fb 100644
--- a/tests/ui/string_add_assign.rs
+++ b/tests/ui/string_add_assign.rs
@@ -4,13 +4,13 @@
#[warn(clippy::string_add_assign)]
fn main() {
// ignores assignment distinction
- let mut x = "".to_owned();
+ let mut x = String::new();
for _ in 1..3 {
x = x + ".";
}
- let y = "".to_owned();
+ let y = String::new();
let z = y + "...";
assert_eq!(&x, &z);
diff --git a/tests/ui/unnecessary_owned_empty_strings.fixed b/tests/ui/unnecessary_owned_empty_strings.fixed
index f95f91329a2..c390618ca98 100644
--- a/tests/ui/unnecessary_owned_empty_strings.fixed
+++ b/tests/ui/unnecessary_owned_empty_strings.fixed
@@ -12,6 +12,7 @@ fn main() {
ref_str_argument("");
// should be linted
+ #[allow(clippy::manual_empty_string_creations)]
ref_str_argument("");
// should not be linted
diff --git a/tests/ui/unnecessary_owned_empty_strings.rs b/tests/ui/unnecessary_owned_empty_strings.rs
index 0cbdc151ed9..4a9d6125eb1 100644
--- a/tests/ui/unnecessary_owned_empty_strings.rs
+++ b/tests/ui/unnecessary_owned_empty_strings.rs
@@ -12,6 +12,7 @@ fn main() {
ref_str_argument(&String::new());
// should be linted
+ #[allow(clippy::manual_empty_string_creations)]
ref_str_argument(&String::from(""));
// should not be linted
diff --git a/tests/ui/unnecessary_owned_empty_strings.stderr b/tests/ui/unnecessary_owned_empty_strings.stderr
index 46bc4597b33..1eb198a8675 100644
--- a/tests/ui/unnecessary_owned_empty_strings.stderr
+++ b/tests/ui/unnecessary_owned_empty_strings.stderr
@@ -7,7 +7,7 @@ LL | ref_str_argument(&String::new());
= note: `-D clippy::unnecessary-owned-empty-strings` implied by `-D warnings`
error: usage of `&String::from("")` for a function expecting a `&str` argument
- --> $DIR/unnecessary_owned_empty_strings.rs:15:22
+ --> $DIR/unnecessary_owned_empty_strings.rs:16:22
|
LL | ref_str_argument(&String::from(""));
| ^^^^^^^^^^^^^^^^^ help: try: `""`
diff --git a/tests/ui/useless_conversion_try.rs b/tests/ui/useless_conversion_try.rs
index 39f54c27bee..4acf5b5fa2d 100644
--- a/tests/ui/useless_conversion_try.rs
+++ b/tests/ui/useless_conversion_try.rs
@@ -29,10 +29,10 @@ fn main() {
let _ = String::try_from("foo".to_string()).unwrap();
let _ = String::try_from(format!("A: {:04}", 123)).unwrap();
let _: String = format!("Hello {}", "world").try_into().unwrap();
- let _: String = "".to_owned().try_into().unwrap();
+ let _: String = String::new().try_into().unwrap();
let _: String = match String::from("_").try_into() {
Ok(a) => a,
- Err(_) => "".into(),
+ Err(_) => String::new(),
};
// FIXME this is a false negative
#[allow(clippy::cmp_owned)]
diff --git a/tests/ui/useless_conversion_try.stderr b/tests/ui/useless_conversion_try.stderr
index b691c13f7db..12e74d61471 100644
--- a/tests/ui/useless_conversion_try.stderr
+++ b/tests/ui/useless_conversion_try.stderr
@@ -62,7 +62,7 @@ LL | let _: String = format!("Hello {}", "world").try_into().unwrap();
error: useless conversion to the same type: `std::string::String`
--> $DIR/useless_conversion_try.rs:32:21
|
-LL | let _: String = "".to_owned().try_into().unwrap();
+LL | let _: String = String::new().try_into().unwrap();
| ^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: consider removing `.try_into()`