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Handle let ref in toplevel_ref_arg as well

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This commit is contained in:
Manish Goregaokar 2015-09-22 12:38:42 +05:30
parent b56ff4319e
commit 3609a2211a
4 changed files with 39 additions and 6 deletions
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4
README.md
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@ -9,7 +9,7 @@ A collection of lints that give helpful tips to newbies and catch oversights.
There are 58 lints included in this crate:
name | default | meaning
-------------------------------------------------------------------------------------------------------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------|---------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
[approx_constant](https://github.com/Manishearth/rust-clippy/wiki#approx_constant) | warn | the approximate of a known float constant (in `std::f64::consts` or `std::f32::consts`) is found; suggests to use the constant
[bad_bit_mask](https://github.com/Manishearth/rust-clippy/wiki#bad_bit_mask) | warn | expressions of the form `_ & mask == select` that will only ever return `true` or `false` (because in the example `select` containing bits that `mask` doesn't have)
[box_vec](https://github.com/Manishearth/rust-clippy/wiki#box_vec) | warn | usage of `Box<Vec<T>>`, vector elements are already on the heap
@ -59,7 +59,7 @@ name
[string_add](https://github.com/Manishearth/rust-clippy/wiki#string_add) | allow | using `x + ..` where x is a `String`; suggests using `push_str()` instead
[string_add_assign](https://github.com/Manishearth/rust-clippy/wiki#string_add_assign) | allow | using `x = x + ..` where x is a `String`; suggests using `push_str()` instead
[string_to_string](https://github.com/Manishearth/rust-clippy/wiki#string_to_string) | warn | calling `String.to_string()` which is a no-op
[toplevel_ref_arg](https://github.com/Manishearth/rust-clippy/wiki#toplevel_ref_arg) | warn | a function argument is declared `ref` (i.e. `fn foo(ref x: u8)`, but not `fn foo((ref x, ref y): (u8, u8))`)
[toplevel_ref_arg](https://github.com/Manishearth/rust-clippy/wiki#toplevel_ref_arg) | warn | An entire binding was declared as `ref`, in a function argument (`fn foo(ref x: Bar)`), or a `let` statement (`let ref x = foo()`). In such cases, it is preferred to take references with `&`.
[type_complexity](https://github.com/Manishearth/rust-clippy/wiki#type_complexity) | warn | usage of very complex types; recommends factoring out parts into `type` definitions
[unicode_not_nfc](https://github.com/Manishearth/rust-clippy/wiki#unicode_not_nfc) | allow | using a unicode literal not in NFC normal form (see http://www.unicode.org/reports/tr15/ for further information)
[unit_cmp](https://github.com/Manishearth/rust-clippy/wiki#unit_cmp) | warn | comparing unit values (which is always `true` or `false`, respectively)

29
src/misc.rs
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@ -8,11 +8,13 @@
use rustc::middle::ty;
use utils::{get_item_name, match_path, snippet, span_lint, walk_ptrs_ty, is_integer_literal};
use utils::span_help_and_lint;
use consts::constant;
declare_lint!(pub TOPLEVEL_REF_ARG, Warn,
"a function argument is declared `ref` (i.e. `fn foo(ref x: u8)`, but not \
`fn foo((ref x, ref y): (u8, u8))`)");
"An entire binding was declared as `ref`, in a function argument (`fn foo(ref x: Bar)`), \
or a `let` statement (`let ref x = foo()`). In such cases, it is preferred to take \
references with `&`.");
#[allow(missing_copy_implementations)]
pub struct TopLevelRefPass;
@ -39,6 +41,29 @@ fn check_fn(&mut self, cx: &LateContext, k: FnKind, decl: &FnDecl, _: &Block, _:
}
}
}
fn check_stmt(&mut self, cx: &LateContext, s: &Stmt) {
if_let_chain! {
[
let StmtDecl(ref d, _) = s.node,
let DeclLocal(ref l) = d.node,
let PatIdent(BindByRef(_), i, None) = l.pat.node,
let Some(ref init) = l.init
], {
let tyopt = if let Some(ref ty) = l.ty {
format!(": {:?} ", ty)
} else {
"".to_owned()
};
span_help_and_lint(cx,
TOPLEVEL_REF_ARG,
l.pat.span,
"`ref` on an entire `let` pattern is discouraged, take a reference with & instead",
&format!("try `let {} {}= &{};`", snippet(cx, i.span, "_"),
tyopt, snippet(cx, init.span, "_"))
);
}
};
}
}
declare_lint!(pub CMP_NAN, Deny,

4
tests/compile-fail/matches.rs
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@ -40,7 +40,7 @@ fn single_match(){
fn ref_pats() {
{
let ref v = Some(0);
let v = &Some(0);
match v { //~ERROR instead of prefixing all patterns with `&`
&Some(v) => println!("{:?}", v),
&None => println!("none"),
@ -50,7 +50,7 @@ fn ref_pats() {
other => println!("other"),
}
}
let ref tup = (1, 2);
let tup =& (1, 2);
match tup { //~ERROR instead of prefixing all patterns with `&`
&(v, 1) => println!("{}", v),
_ => println!("none"),

8
tests/compile-fail/toplevel_ref_arg.rs
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@ -14,5 +14,13 @@ fn main() {
// Closures should not warn
let y = |ref x| { println!("{:?}", x) };
y(1u8);
let ref x = 1; //~ ERROR `ref` on an entire `let` pattern is discouraged
//~^ HELP try `let x = &1;`
let ref y = (&1, 2); //~ ERROR `ref` on an entire `let` pattern is discouraged
//~^ HELP try `let y = &(&1, 2);`
let (ref x, _) = (1,2); // okay, not top level
println!("The answer is {}.", x);
}