78 lines
2.6 KiB
Rust
78 lines
2.6 KiB
Rust
//! This LintPass catches both string addition and string addition + assignment
|
|
//!
|
|
//! Note that since we have two lints where one subsumes the other, we try to
|
|
//! disable the subsumed lint unless it has a higher level
|
|
|
|
use rustc::lint::*;
|
|
use rustc_front::hir::*;
|
|
use syntax::codemap::Spanned;
|
|
|
|
use eq_op::is_exp_equal;
|
|
use utils::{match_type, span_lint, walk_ptrs_ty, get_parent_expr};
|
|
use utils::STRING_PATH;
|
|
|
|
declare_lint! {
|
|
pub STRING_ADD_ASSIGN,
|
|
Allow,
|
|
"using `x = x + ..` where x is a `String`; suggests using `push_str()` instead"
|
|
}
|
|
|
|
declare_lint! {
|
|
pub STRING_ADD,
|
|
Allow,
|
|
"using `x + ..` where x is a `String`; suggests using `push_str()` instead"
|
|
}
|
|
|
|
#[derive(Copy, Clone)]
|
|
pub struct StringAdd;
|
|
|
|
impl LintPass for StringAdd {
|
|
fn get_lints(&self) -> LintArray {
|
|
lint_array!(STRING_ADD, STRING_ADD_ASSIGN)
|
|
}
|
|
}
|
|
|
|
impl LateLintPass for StringAdd {
|
|
fn check_expr(&mut self, cx: &LateContext, 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(cx, target, left) { return; }
|
|
}
|
|
}
|
|
}
|
|
span_lint(cx, STRING_ADD, e.span,
|
|
"you added something to a string. \
|
|
Consider using `String::push_str()` instead")
|
|
}
|
|
} else if let &ExprAssign(ref target, ref src) = &e.node {
|
|
if is_string(cx, target) && is_add(cx, src, target) {
|
|
span_lint(cx, STRING_ADD_ASSIGN, e.span,
|
|
"you assigned the result of adding something to this string. \
|
|
Consider using `String::push_str()` instead")
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn is_string(cx: &LateContext, e: &Expr) -> bool {
|
|
match_type(cx, walk_ptrs_ty(cx.tcx.expr_ty(e)), &STRING_PATH)
|
|
}
|
|
|
|
fn is_add(cx: &LateContext, src: &Expr, target: &Expr) -> bool {
|
|
match src.node {
|
|
ExprBinary(Spanned{ node: BiAdd, .. }, ref left, _) =>
|
|
is_exp_equal(cx, target, left),
|
|
ExprBlock(ref block) => block.stmts.is_empty() &&
|
|
block.expr.as_ref().map_or(false,
|
|
|expr| is_add(cx, expr, target)),
|
|
_ => false
|
|
}
|
|
}
|