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rustc_pass_by_value lint: add test on custom types

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This commit is contained in:
Mahdi Dibaiee 2022-01-10 08:54:42 +00:00
parent 4c3e330a8c
commit 91ed6892f7
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GPG Key ID: BABA115BDF0C598A
4 changed files with 82 additions and 22 deletions
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1
compiler/rustc_lint/src/pass_by_value.rs
View File

@ -11,6 +11,7 @@ declare_tool_lint! {
/// The `rustc_pass_by_value` lint marks a type with `#[rustc_pass_by_value]` requiring it to always be passed by value.
/// This is usually used for types that are thin wrappers around references, so there is no benefit to an extra
/// layer of indirection. (Example: `Ty` which is a reference to a `TyS`)
/// This lint relies on `#[rustc_diagnostic_item]` being available for the target.
pub rustc::PASS_BY_VALUE,
Warn,
"pass by reference of a type flagged as `#[rustc_pass_by_value]`",

11
compiler/rustc_passes/src/check_attr.rs
View File

@ -1070,20 +1070,15 @@ impl CheckAttrVisitor<'_> {
/// Warns against some misuses of `#[pass_by_value]`
fn check_pass_by_value(&self, attr: &Attribute, span: &Span, target: Target) -> bool {
match target {
Target::Struct
| Target::Enum
| Target::Union
| Target::Trait
| Target::TraitAlias
| Target::TyAlias => true,
Target::Struct | Target::Enum | Target::TyAlias => true,
_ => {
self.tcx
.sess
.struct_span_err(
attr.span,
"`pass_by_value` attribute should be applied to a struct, enum, trait or type alias.",
"`pass_by_value` attribute should be applied to a struct, enum or type alias.",
)
.span_label(*span, "is not a struct, enum, trait or type alias")
.span_label(*span, "is not a struct, enum or type alias")
.emit();
false
}

40
src/test/ui-fulldeps/internal-lints/rustc_pass_by_value.rs
View File

@ -1,5 +1,6 @@
// compile-flags: -Z unstable-options
#![feature(rustc_attrs)]
#![feature(rustc_private)]
#![deny(rustc::pass_by_value)]
#![allow(unused)]
@ -61,4 +62,43 @@ impl Foo {
//~^^ ERROR passing `TyCtxt<'_>` by reference
}
#[rustc_diagnostic_item = "CustomEnum"]
#[rustc_pass_by_value]
enum CustomEnum {
A,
B,
}
impl CustomEnum {
fn test(
value: CustomEnum,
reference: &CustomEnum, //~ ERROR passing `CustomEnum` by reference
) {
}
}
#[rustc_diagnostic_item = "CustomStruct"]
#[rustc_pass_by_value]
struct CustomStruct {
s: u8,
}
#[rustc_diagnostic_item = "CustomAlias"]
#[rustc_pass_by_value]
type CustomAlias<'a> = &'a CustomStruct; //~ ERROR passing `CustomStruct` by reference
impl CustomStruct {
fn test(
value: CustomStruct,
reference: &CustomStruct, //~ ERROR passing `CustomStruct` by reference
) {
}
fn test_alias(
value: CustomAlias,
reference: &CustomAlias, //~ ERROR passing `CustomAlias<>` by reference
) {
}
}
fn main() {}

52
src/test/ui-fulldeps/internal-lints/rustc_pass_by_value.stderr
View File

@ -1,80 +1,104 @@
error: passing `Ty<'_>` by reference
--> $DIR/rustc_pass_by_value.rs:13:13
--> $DIR/rustc_pass_by_value.rs:14:13
|
LL | ty_ref: &Ty<'_>,
| ^^^^^^^ help: try passing by value: `Ty<'_>`
|
note: the lint level is defined here
--> $DIR/rustc_pass_by_value.rs:4:9
--> $DIR/rustc_pass_by_value.rs:5:9
|
LL | #![deny(rustc::pass_by_value)]
| ^^^^^^^^^^^^^^^^^^^^
error: passing `TyCtxt<'_>` by reference
--> $DIR/rustc_pass_by_value.rs:15:18
--> $DIR/rustc_pass_by_value.rs:16:18
|
LL | ty_ctxt_ref: &TyCtxt<'_>,
| ^^^^^^^^^^^ help: try passing by value: `TyCtxt<'_>`
error: passing `Ty<'_>` by reference
--> $DIR/rustc_pass_by_value.rs:19:28
--> $DIR/rustc_pass_by_value.rs:20:28
|
LL | fn ty_multi_ref(ty_multi: &&Ty<'_>, ty_ctxt_multi: &&&&TyCtxt<'_>) {}
| ^^^^^^^ help: try passing by value: `Ty<'_>`
error: passing `TyCtxt<'_>` by reference
--> $DIR/rustc_pass_by_value.rs:19:55
--> $DIR/rustc_pass_by_value.rs:20:55
|
LL | fn ty_multi_ref(ty_multi: &&Ty<'_>, ty_ctxt_multi: &&&&TyCtxt<'_>) {}
| ^^^^^^^^^^^ help: try passing by value: `TyCtxt<'_>`
error: passing `Ty<'_>` by reference
--> $DIR/rustc_pass_by_value.rs:26:17
--> $DIR/rustc_pass_by_value.rs:27:17
|
LL | ty_ref: &Ty<'_>,
| ^^^^^^^ help: try passing by value: `Ty<'_>`
error: passing `TyCtxt<'_>` by reference
--> $DIR/rustc_pass_by_value.rs:28:22
--> $DIR/rustc_pass_by_value.rs:29:22
|
LL | ty_ctxt_ref: &TyCtxt<'_>,
| ^^^^^^^^^^^ help: try passing by value: `TyCtxt<'_>`
error: passing `Ty<'_>` by reference
--> $DIR/rustc_pass_by_value.rs:31:41
--> $DIR/rustc_pass_by_value.rs:32:41
|
LL | fn ty_multi_ref_in_trait(ty_multi: &&Ty<'_>, ty_ctxt_multi: &&&&TyCtxt<'_>);
| ^^^^^^^ help: try passing by value: `Ty<'_>`
error: passing `TyCtxt<'_>` by reference
--> $DIR/rustc_pass_by_value.rs:31:68
--> $DIR/rustc_pass_by_value.rs:32:68
|
LL | fn ty_multi_ref_in_trait(ty_multi: &&Ty<'_>, ty_ctxt_multi: &&&&TyCtxt<'_>);
| ^^^^^^^^^^^ help: try passing by value: `TyCtxt<'_>`
error: passing `Ty<'_>` by reference
--> $DIR/rustc_pass_by_value.rs:53:17
--> $DIR/rustc_pass_by_value.rs:54:17
|
LL | ty_ref: &Ty<'_>,
| ^^^^^^^ help: try passing by value: `Ty<'_>`
error: passing `TyCtxt<'_>` by reference
--> $DIR/rustc_pass_by_value.rs:55:22
--> $DIR/rustc_pass_by_value.rs:56:22
|
LL | ty_ctxt_ref: &TyCtxt<'_>,
| ^^^^^^^^^^^ help: try passing by value: `TyCtxt<'_>`
error: passing `Ty<'_>` by reference
--> $DIR/rustc_pass_by_value.rs:59:38
--> $DIR/rustc_pass_by_value.rs:60:38
|
LL | fn ty_multi_ref_assoc(ty_multi: &&Ty<'_>, ty_ctxt_multi: &&&&TyCtxt<'_>) {}
| ^^^^^^^ help: try passing by value: `Ty<'_>`
error: passing `TyCtxt<'_>` by reference
--> $DIR/rustc_pass_by_value.rs:59:65
--> $DIR/rustc_pass_by_value.rs:60:65
|
LL | fn ty_multi_ref_assoc(ty_multi: &&Ty<'_>, ty_ctxt_multi: &&&&TyCtxt<'_>) {}
| ^^^^^^^^^^^ help: try passing by value: `TyCtxt<'_>`
error: aborting due to 12 previous errors
error: passing `CustomEnum` by reference
--> $DIR/rustc_pass_by_value.rs:75:20
|
LL | reference: &CustomEnum,
| ^^^^^^^^^^^ help: try passing by value: `CustomEnum`
error: passing `CustomStruct` by reference
--> $DIR/rustc_pass_by_value.rs:88:24
|
LL | type CustomAlias<'a> = &'a CustomStruct;
| ^^^^^^^^^^^^^^^^ help: try passing by value: `CustomStruct`
error: passing `CustomStruct` by reference
--> $DIR/rustc_pass_by_value.rs:93:20
|
LL | reference: &CustomStruct,
| ^^^^^^^^^^^^^ help: try passing by value: `CustomStruct`
error: passing `CustomAlias<>` by reference
--> $DIR/rustc_pass_by_value.rs:99:20
|
LL | reference: &CustomAlias,
| ^^^^^^^^^^^^ help: try passing by value: `CustomAlias<>`
error: aborting due to 16 previous errors