added string_add lint and fixed string_add_assign + test

This commit is contained in:
llogiq 2015-08-12 15:50:56 +02:00
parent 8dfa02938d
commit 0b08e9e83e
4 changed files with 54 additions and 8 deletions

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@ -30,6 +30,7 @@ Lints included in this crate:
- `collapsible_if`: Warns on cases where two nested `if`-expressions can be collapsed into one, e.g. `if x { if y { foo() } }` can be written as `if x && y { foo() }`
- `zero_width_space`: Warns on encountering a unicode zero-width space
- `string_add_assign`: Warns on `x = x + ..` where `x` is a `String` and suggests using `push_str(..)` instead.
- `string_add`: Matches `x + ..` where `x` is a `String` and where `string_add_assign` doesn't warn. Allowed by default.
- `needless_return`: Warns on using `return expr;` when a simple `expr` would suffice.
- `let_and_return`: Warns on doing `let x = expr; x` at the end of a function.
- `option_unwrap_used`: Warns when `Option.unwrap()` is used, and suggests `.expect()`.

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@ -58,6 +58,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
reg.register_lint_pass(box misc::ModuloOne as LintPassObject);
reg.register_lint_pass(box unicode::Unicode as LintPassObject);
reg.register_lint_pass(box strings::StringAdd as LintPassObject);
reg.register_lint_pass(box strings::StringAddAssign as LintPassObject);
reg.register_lint_pass(box returns::ReturnPass as LintPassObject);
reg.register_lint_pass(box methods::MethodsPass as LintPassObject);
reg.register_lint_pass(box types::LetPass as LintPassObject);

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@ -9,7 +9,7 @@ use syntax::ast::*;
use syntax::codemap::{Span, Spanned};
use eq_op::is_exp_equal;
use types::match_ty_unwrap;
use utils::{match_def_path, span_lint, walk_ptrs_ty};
use utils::{match_def_path, span_lint, walk_ptrs_ty, get_parent_expr};
declare_lint! {
pub STRING_ADD_ASSIGN,
@ -17,10 +17,48 @@ declare_lint! {
"Warn on `x = x + ..` where x is a `String`"
}
#[derive(Copy,Clone)]
declare_lint! {
pub STRING_ADD,
Allow,
"Warn on `x + ..` where x is a `String`"
}
#[derive(Copy, Clone)]
pub struct StringAdd;
impl LintPass for StringAdd {
fn get_lints(&self) -> LintArray {
lint_array!(STRING_ADD)
}
fn check_expr(&mut self, cx: &Context, e: &Expr) {
if let &ExprBinary(Spanned{ node: BiAdd, .. }, ref left, _) = &e.node {
if is_string(cx, left) {
if let Allow = cx.current_level(STRING_ADD_ASSIGN) {
// the string_add_assign is allow, so no duplicates
} else {
let parent = get_parent_expr(cx, e);
if let Some(ref p) = parent {
if let &ExprAssign(ref target, _) = &p.node {
// avoid duplicate matches
if is_exp_equal(target, left) { return; }
}
}
}
//TODO check for duplicates
span_lint(cx, STRING_ADD, e.span,
"you add something to a string. \
Consider using `String::push_str()` instead.")
}
}
}
}
#[derive(Copy, Clone)]
pub struct StringAddAssign;
impl LintPass for StringAddAssign {
fn get_lints(&self) -> LintArray {
lint_array!(STRING_ADD_ASSIGN)
}
@ -37,8 +75,9 @@ impl LintPass for StringAdd {
}
fn is_string(cx: &Context, e: &Expr) -> bool {
if let TyStruct(did, _) = walk_ptrs_ty(cx.tcx.expr_ty(e)).sty {
match_def_path(cx, did.did, &["std", "string", "String"])
let ty = walk_ptrs_ty(cx.tcx.expr_ty(e));
if let TyStruct(did, _) = ty.sty {
match_def_path(cx, did.did, &["collections", "string", "String"])
} else { false }
}

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@ -2,11 +2,16 @@
#![plugin(clippy)]
#![deny(string_add_assign)]
#![deny(string_add)]
fn main() {
let x = "".to_owned();
let mut x = "".to_owned();
for i in (1..3) {
x = x + "."; //~ERROR
for _ in (1..3) {
x = x + "."; //~ERROR you assign the result of adding something to this string.
}
let y = "".to_owned();
let z = y + "..."; //~ERROR you add something to a string.
assert_eq!(&x, &z);
}