Suggest inline const blocks for array initialization
This commit is contained in:
Pavel Grigorenko
parent
2c243d9570
commit
ba5ec1fc5c
@ -2915,38 +2915,21 @@ fn note_obligation_cause_code<G: EmissionGuarantee, T>(
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}
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ObligationCauseCode::RepeatElementCopy {
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is_constable,
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elt_type,
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elt_type: _,
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elt_span,
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elt_stmt_span,
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elt_stmt_span: _,
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} => {
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err.note(
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"the `Copy` trait is required because this value will be copied for each element of the array",
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);
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let value_kind = match is_constable {
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IsConstable::Fn => Some("the result of the function call"),
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IsConstable::Ctor => Some("the result of the constructor"),
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_ => None,
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};
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let sm = tcx.sess.source_map();
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if let Some(value_kind) = value_kind
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if matches!(is_constable, IsConstable::Fn | IsConstable::Ctor)
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&& let Ok(snip) = sm.span_to_snippet(elt_span)
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{
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let help_msg = format!(
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"consider creating a new `const` item and initializing it with {value_kind} \
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to be used in the repeat position"
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);
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let indentation = sm.indentation_before(elt_stmt_span).unwrap_or_default();
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err.multipart_suggestion(
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help_msg,
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vec![
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(
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elt_stmt_span.shrink_to_lo(),
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format!(
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"const ARRAY_REPEAT_VALUE: {elt_type} = {snip};\n{indentation}"
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),
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),
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(elt_span, "ARRAY_REPEAT_VALUE".to_string()),
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],
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err.span_suggestion(
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elt_span,
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"create an inline `const` block",
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format!("const {{ {snip} }}"),
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Applicability::MachineApplicable,
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);
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} else {
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@ -2954,15 +2937,6 @@ fn note_obligation_cause_code<G: EmissionGuarantee, T>(
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err.help("consider using `core::array::from_fn` to initialize the array");
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err.help("see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html for more information");
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}
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if tcx.sess.is_nightly_build()
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&& matches!(is_constable, IsConstable::Fn | IsConstable::Ctor)
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{
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err.help(
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"create an inline `const` block, see RFC #2920 \
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<https://github.com/rust-lang/rfcs/pull/2920> for more information",
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);
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}
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}
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ObligationCauseCode::VariableType(hir_id) => {
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if let Some(typeck_results) = &self.typeck_results
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@ -6,17 +6,15 @@ LL | let _: [Option<Bar>; 2] = [no_copy(); 2];
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= note: required for `Option<Bar>` to implement `Copy`
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= note: the `Copy` trait is required because this value will be copied for each element of the array
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= help: create an inline `const` block, see RFC #2920 <https://github.com/rust-lang/rfcs/pull/2920> for more information
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help: consider annotating `Bar` with `#[derive(Copy)]`
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LL + #[derive(Copy)]
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LL | struct Bar;
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help: consider creating a new `const` item and initializing it with the result of the function call to be used in the repeat position
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LL ~ const ARRAY_REPEAT_VALUE: Option<Bar> = no_copy();
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LL ~ let _: [Option<Bar>; 2] = [ARRAY_REPEAT_VALUE; 2];
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help: create an inline `const` block
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LL | let _: [Option<Bar>; 2] = [const { no_copy() }; 2];
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| ~~~~~~~~~~~~~~~~~~~
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error: aborting due to 1 previous error
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@ -2,7 +2,10 @@ error[E0277]: the trait bound `String: Copy` is not satisfied
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--> $DIR/trait-error.rs:5:6
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LL | [Foo(String::new()); 4];
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| ^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `String`, which is required by `Foo<String>: Copy`
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| ^^^^^^^^^^^^^^^^^^
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| |
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| the trait `Copy` is not implemented for `String`, which is required by `Foo<String>: Copy`
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| help: create an inline `const` block: `const { Foo(String::new()) }`
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note: required for `Foo<String>` to implement `Copy`
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--> $DIR/trait-error.rs:1:10
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@ -10,13 +13,7 @@ note: required for `Foo<String>` to implement `Copy`
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LL | #[derive(Copy, Clone)]
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| ^^^^ unsatisfied trait bound introduced in this `derive` macro
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= note: the `Copy` trait is required because this value will be copied for each element of the array
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= help: create an inline `const` block, see RFC #2920 <https://github.com/rust-lang/rfcs/pull/2920> for more information
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= note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
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help: consider creating a new `const` item and initializing it with the result of the function call to be used in the repeat position
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LL ~ const ARRAY_REPEAT_VALUE: Foo<String> = Foo(String::new());
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LL ~ [ARRAY_REPEAT_VALUE; 4];
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error: aborting due to 1 previous error
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@ -2,45 +2,36 @@ error[E0277]: the trait bound `String: Copy` is not satisfied
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--> $DIR/const-fn-in-vec.rs:1:47
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LL | static _MAYBE_STRINGS: [Option<String>; 5] = [None; 5];
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| ^^^^ the trait `Copy` is not implemented for `String`, which is required by `Option<String>: Copy`
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| ^^^^
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| |
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| the trait `Copy` is not implemented for `String`, which is required by `Option<String>: Copy`
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| help: create an inline `const` block: `const { None }`
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= note: required for `Option<String>` to implement `Copy`
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= note: the `Copy` trait is required because this value will be copied for each element of the array
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= help: create an inline `const` block, see RFC #2920 <https://github.com/rust-lang/rfcs/pull/2920> for more information
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help: consider creating a new `const` item and initializing it with the result of the constructor to be used in the repeat position
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LL + const ARRAY_REPEAT_VALUE: Option<String> = None;
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LL ~ static _MAYBE_STRINGS: [Option<String>; 5] = [ARRAY_REPEAT_VALUE; 5];
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error[E0277]: the trait bound `String: Copy` is not satisfied
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--> $DIR/const-fn-in-vec.rs:7:34
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LL | let _strings: [String; 5] = [String::new(); 5];
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| ^^^^^^^^^^^^^ the trait `Copy` is not implemented for `String`
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| ^^^^^^^^^^^^^
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| |
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| the trait `Copy` is not implemented for `String`
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| help: create an inline `const` block: `const { String::new() }`
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= note: the `Copy` trait is required because this value will be copied for each element of the array
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= help: create an inline `const` block, see RFC #2920 <https://github.com/rust-lang/rfcs/pull/2920> for more information
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help: consider creating a new `const` item and initializing it with the result of the function call to be used in the repeat position
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LL ~ const ARRAY_REPEAT_VALUE: String = String::new();
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LL ~ let _strings: [String; 5] = [ARRAY_REPEAT_VALUE; 5];
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error[E0277]: the trait bound `String: Copy` is not satisfied
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--> $DIR/const-fn-in-vec.rs:9:48
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LL | let _maybe_strings: [Option<String>; 5] = [None; 5];
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| ^^^^ the trait `Copy` is not implemented for `String`, which is required by `Option<String>: Copy`
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| ^^^^
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| |
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| the trait `Copy` is not implemented for `String`, which is required by `Option<String>: Copy`
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| help: create an inline `const` block: `const { None }`
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= note: required for `Option<String>` to implement `Copy`
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= note: the `Copy` trait is required because this value will be copied for each element of the array
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= help: create an inline `const` block, see RFC #2920 <https://github.com/rust-lang/rfcs/pull/2920> for more information
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help: consider creating a new `const` item and initializing it with the result of the constructor to be used in the repeat position
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LL ~ const ARRAY_REPEAT_VALUE: Option<String> = None;
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LL ~ let _maybe_strings: [Option<String>; 5] = [ARRAY_REPEAT_VALUE; 5];
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error: aborting due to 3 previous errors
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