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Added suggestion to function_item_references lint and fixed warning message

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Also updated tests accordingly and tweaked some wording in the lint declaration.
This commit is contained in:
Ayrton 2020-10-27 09:00:19 -04:00
parent 935fc3642a
commit c791c64e84
4 changed files with 102 additions and 95 deletions
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27
compiler/rustc_mir/src/transform/function_item_references.rs
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@ -1,3 +1,4 @@
use rustc_errors::Applicability;
use rustc_hir::def_id::DefId;
use rustc_middle::mir::visit::Visitor;
use rustc_middle::mir::*;
@ -183,16 +184,22 @@ impl<'a, 'tcx> FunctionItemRefChecker<'a, 'tcx> {
let variadic = if fn_sig.c_variadic() { ", ..." } else { "" };
let ret = if fn_sig.output().skip_binder().is_unit() { "" } else { " -> _" };
self.tcx.struct_span_lint_hir(FUNCTION_ITEM_REFERENCES, lint_root, span, |lint| {
lint.build(&format!(
"cast `{}` with `as {}{}fn({}{}){}` to obtain a function pointer",
ident,
unsafety,
abi,
vec!["_"; num_args].join(", "),
variadic,
ret,
))
.emit();
lint.build("taking a reference to a function item does not give a function pointer")
.span_suggestion(
span,
&format!("cast `{}` to obtain a function pointer", ident),
format!(
"{} as {}{}fn({}{}){}",
ident,
unsafety,
abi,
vec!["_"; num_args].join(", "),
variadic,
ret,
),
Applicability::Unspecified,
)
.emit();
});
}
}

2
compiler/rustc_session/src/lint/builtin.rs
View File

@ -2674,7 +2674,7 @@ declare_lint! {
/// arguments bound by [`fmt::Pointer`] or transmuted.
pub FUNCTION_ITEM_REFERENCES,
Warn,
"suggest casting functions to pointers when attempting to take references",
"suggest casting to a function pointer when attempting to take references to function items",
}
declare_lint! {

56
src/test/ui/lint/function-item-references.rs
View File

@ -38,7 +38,7 @@ fn _format_assoc_item<T: HasItem>(data: T, f: &mut Formatter) -> std::fmt::Resul
fn _call_pointer_fmt(f: &mut Formatter) -> std::fmt::Result {
let zst_ref = &foo;
Pointer::fmt(&zst_ref, f)
//~^ WARNING cast `foo` with `as fn() -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
}
fn main() {
@ -75,47 +75,47 @@ fn main() {
//potential ways to incorrectly try printing function pointers
println!("{:p}", &foo);
//~^ WARNING cast `foo` with `as fn() -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
print!("{:p}", &foo);
//~^ WARNING cast `foo` with `as fn() -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
format!("{:p}", &foo);
//~^ WARNING cast `foo` with `as fn() -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
println!("{:p}", &foo as *const _);
//~^ WARNING cast `foo` with `as fn() -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
println!("{:p}", zst_ref);
//~^ WARNING cast `foo` with `as fn() -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
println!("{:p}", cast_zst_ptr);
//~^ WARNING cast `foo` with `as fn() -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
println!("{:p}", coerced_zst_ptr);
//~^ WARNING cast `foo` with `as fn() -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
println!("{:p}", &fn_item);
//~^ WARNING cast `foo` with `as fn() -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
println!("{:p}", indirect_ref);
//~^ WARNING cast `foo` with `as fn() -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
println!("{:p}", &nop);
//~^ WARNING cast `nop` with `as fn()` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
println!("{:p}", &bar);
//~^ WARNING cast `bar` with `as fn(_) -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
println!("{:p}", &baz);
//~^ WARNING cast `baz` with `as fn(_, _) -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
println!("{:p}", &unsafe_fn);
//~^ WARNING cast `unsafe_fn` with `as unsafe fn()` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
println!("{:p}", &c_fn);
//~^ WARNING cast `c_fn` with `as extern "C" fn()` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
println!("{:p}", &unsafe_c_fn);
//~^ WARNING cast `unsafe_c_fn` with `as unsafe extern "C" fn()` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
println!("{:p}", &variadic);
//~^ WARNING cast `variadic` with `as unsafe extern "C" fn(_, ...)` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
println!("{:p}", &std::env::var::<String>);
//~^ WARNING cast `var` with `as fn(_) -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
println!("{:p} {:p} {:p}", &nop, &foo, &bar);
//~^ WARNING cast `nop` with `as fn()` to obtain a function pointer
//~^^ WARNING cast `foo` with `as fn() -> _` to obtain a function pointer
//~^^^ WARNING cast `bar` with `as fn(_) -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
//~^^ WARNING taking a reference to a function item does not give a function pointer
//~^^^ WARNING taking a reference to a function item does not give a function pointer
//using a function reference to call a function shouldn't lint
(&bar)(1);
@ -128,10 +128,10 @@ fn main() {
unsafe {
//potential ways to incorrectly try transmuting function pointers
std::mem::transmute::<_, usize>(&foo);
//~^ WARNING cast `foo` with `as fn() -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
std::mem::transmute::<_, (usize, usize)>((&foo, &bar));
//~^ WARNING cast `foo` with `as fn() -> _` to obtain a function pointer
//~^^ WARNING cast `bar` with `as fn(_) -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
//~^^ WARNING taking a reference to a function item does not give a function pointer
//the correct way to transmute function pointers
std::mem::transmute::<_, usize>(foo as fn() -> u32);
@ -140,12 +140,12 @@ fn main() {
//function references as arguments required to be bound by std::fmt::Pointer should lint
print_ptr(&bar);
//~^ WARNING cast `bar` with `as fn(_) -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
bound_by_ptr_trait(&bar);
//~^ WARNING cast `bar` with `as fn(_) -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
bound_by_ptr_trait_tuple((&foo, &bar));
//~^ WARNING cast `foo` with `as fn() -> _` to obtain a function pointer
//~^^ WARNING cast `bar` with `as fn(_) -> _` to obtain a function pointer
//~^ WARNING taking a reference to a function item does not give a function pointer
//~^^ WARNING taking a reference to a function item does not give a function pointer
implicit_ptr_trait(&bar); // ignore
//correct ways to pass function pointers as arguments bound by std::fmt::Pointer

112
src/test/ui/lint/function-item-references.stderr
View File

@ -1,8 +1,8 @@
warning: cast `foo` with `as fn() -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:40:18
|
LL | Pointer::fmt(&zst_ref, f)
| ^^^^^^^^
| ^^^^^^^^ help: cast `foo` to obtain a function pointer: `foo as fn() -> _`
|
note: the lint level is defined here
--> $DIR/function-item-references.rs:3:9
@ -10,167 +10,167 @@ note: the lint level is defined here
LL | #![warn(function_item_references)]
| ^^^^^^^^^^^^^^^^^^^^^^^^
warning: cast `foo` with `as fn() -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:77:22
|
LL | println!("{:p}", &foo);
| ^^^^
| ^^^^ help: cast `foo` to obtain a function pointer: `foo as fn() -> _`
warning: cast `foo` with `as fn() -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:79:20
|
LL | print!("{:p}", &foo);
| ^^^^
| ^^^^ help: cast `foo` to obtain a function pointer: `foo as fn() -> _`
warning: cast `foo` with `as fn() -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:81:21
|
LL | format!("{:p}", &foo);
| ^^^^
| ^^^^ help: cast `foo` to obtain a function pointer: `foo as fn() -> _`
warning: cast `foo` with `as fn() -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:84:22
|
LL | println!("{:p}", &foo as *const _);
| ^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^ help: cast `foo` to obtain a function pointer: `foo as fn() -> _`
warning: cast `foo` with `as fn() -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:86:22
|
LL | println!("{:p}", zst_ref);
| ^^^^^^^
| ^^^^^^^ help: cast `foo` to obtain a function pointer: `foo as fn() -> _`
warning: cast `foo` with `as fn() -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:88:22
|
LL | println!("{:p}", cast_zst_ptr);
| ^^^^^^^^^^^^
| ^^^^^^^^^^^^ help: cast `foo` to obtain a function pointer: `foo as fn() -> _`
warning: cast `foo` with `as fn() -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:90:22
|
LL | println!("{:p}", coerced_zst_ptr);
| ^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^ help: cast `foo` to obtain a function pointer: `foo as fn() -> _`
warning: cast `foo` with `as fn() -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:93:22
|
LL | println!("{:p}", &fn_item);
| ^^^^^^^^
| ^^^^^^^^ help: cast `foo` to obtain a function pointer: `foo as fn() -> _`
warning: cast `foo` with `as fn() -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:95:22
|
LL | println!("{:p}", indirect_ref);
| ^^^^^^^^^^^^
| ^^^^^^^^^^^^ help: cast `foo` to obtain a function pointer: `foo as fn() -> _`
warning: cast `nop` with `as fn()` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:98:22
|
LL | println!("{:p}", &nop);
| ^^^^
| ^^^^ help: cast `nop` to obtain a function pointer: `nop as fn()`
warning: cast `bar` with `as fn(_) -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:100:22
|
LL | println!("{:p}", &bar);
| ^^^^
| ^^^^ help: cast `bar` to obtain a function pointer: `bar as fn(_) -> _`
warning: cast `baz` with `as fn(_, _) -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:102:22
|
LL | println!("{:p}", &baz);
| ^^^^
| ^^^^ help: cast `baz` to obtain a function pointer: `baz as fn(_, _) -> _`
warning: cast `unsafe_fn` with `as unsafe fn()` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:104:22
|
LL | println!("{:p}", &unsafe_fn);
| ^^^^^^^^^^
| ^^^^^^^^^^ help: cast `unsafe_fn` to obtain a function pointer: `unsafe_fn as unsafe fn()`
warning: cast `c_fn` with `as extern "C" fn()` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:106:22
|
LL | println!("{:p}", &c_fn);
| ^^^^^
| ^^^^^ help: cast `c_fn` to obtain a function pointer: `c_fn as extern "C" fn()`
warning: cast `unsafe_c_fn` with `as unsafe extern "C" fn()` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:108:22
|
LL | println!("{:p}", &unsafe_c_fn);
| ^^^^^^^^^^^^
| ^^^^^^^^^^^^ help: cast `unsafe_c_fn` to obtain a function pointer: `unsafe_c_fn as unsafe extern "C" fn()`
warning: cast `variadic` with `as unsafe extern "C" fn(_, ...)` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:110:22
|
LL | println!("{:p}", &variadic);
| ^^^^^^^^^
| ^^^^^^^^^ help: cast `variadic` to obtain a function pointer: `variadic as unsafe extern "C" fn(_, ...)`
warning: cast `var` with `as fn(_) -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:112:22
|
LL | println!("{:p}", &std::env::var::<String>);
| ^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: cast `var` to obtain a function pointer: `var as fn(_) -> _`
warning: cast `nop` with `as fn()` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:115:32
|
LL | println!("{:p} {:p} {:p}", &nop, &foo, &bar);
| ^^^^
| ^^^^ help: cast `nop` to obtain a function pointer: `nop as fn()`
warning: cast `foo` with `as fn() -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:115:38
|
LL | println!("{:p} {:p} {:p}", &nop, &foo, &bar);
| ^^^^
| ^^^^ help: cast `foo` to obtain a function pointer: `foo as fn() -> _`
warning: cast `bar` with `as fn(_) -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:115:44
|
LL | println!("{:p} {:p} {:p}", &nop, &foo, &bar);
| ^^^^
| ^^^^ help: cast `bar` to obtain a function pointer: `bar as fn(_) -> _`
warning: cast `foo` with `as fn() -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:130:41
|
LL | std::mem::transmute::<_, usize>(&foo);
| ^^^^
| ^^^^ help: cast `foo` to obtain a function pointer: `foo as fn() -> _`
warning: cast `foo` with `as fn() -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:132:50
|
LL | std::mem::transmute::<_, (usize, usize)>((&foo, &bar));
| ^^^^^^^^^^^^
| ^^^^^^^^^^^^ help: cast `foo` to obtain a function pointer: `foo as fn() -> _`
warning: cast `bar` with `as fn(_) -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:132:50
|
LL | std::mem::transmute::<_, (usize, usize)>((&foo, &bar));
| ^^^^^^^^^^^^
| ^^^^^^^^^^^^ help: cast `bar` to obtain a function pointer: `bar as fn(_) -> _`
warning: cast `bar` with `as fn(_) -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:142:15
|
LL | print_ptr(&bar);
| ^^^^
| ^^^^ help: cast `bar` to obtain a function pointer: `bar as fn(_) -> _`
warning: cast `bar` with `as fn(_) -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:144:24
|
LL | bound_by_ptr_trait(&bar);
| ^^^^
| ^^^^ help: cast `bar` to obtain a function pointer: `bar as fn(_) -> _`
warning: cast `bar` with `as fn(_) -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:146:30
|
LL | bound_by_ptr_trait_tuple((&foo, &bar));
| ^^^^^^^^^^^^
| ^^^^^^^^^^^^ help: cast `bar` to obtain a function pointer: `bar as fn(_) -> _`
warning: cast `foo` with `as fn() -> _` to obtain a function pointer
warning: taking a reference to a function item does not give a function pointer
--> $DIR/function-item-references.rs:146:30
|
LL | bound_by_ptr_trait_tuple((&foo, &bar));
| ^^^^^^^^^^^^
| ^^^^^^^^^^^^ help: cast `foo` to obtain a function pointer: `foo as fn() -> _`
warning: 28 warnings emitted