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use rustc::hir::*;
use rustc::lint::*;
use syntax::codemap::Spanned;
use utils::SpanlessEq;
use utils::{get_parent_expr, is_allowed, match_type, paths, span_lint, span_lint_and_sugg, walk_ptrs_ty};
declare_clippy_lint! {
pub STRING_ADD_ASSIGN,
pedantic,
"using `x = x + ..` where x is a `String` instead of `push_str()`"
}
declare_clippy_lint! {
pub STRING_ADD,
restriction,
"using `x + ..` where x is a `String` instead of `push_str()`"
}
declare_clippy_lint! {
pub STRING_LIT_AS_BYTES,
style,
"calling `as_bytes` on a string literal instead of using a byte string literal"
}
#[derive(Copy, Clone)]
pub struct StringAdd;
impl LintPass for StringAdd {
fn get_lints(&self) -> LintArray {
lint_array!(STRING_ADD, STRING_ADD_ASSIGN)
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for StringAdd {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
if let ExprBinary(Spanned { node: BiAdd, .. }, ref left, _) = e.node {
if is_string(cx, left) {
if !is_allowed(cx, STRING_ADD_ASSIGN, e.id) {
let parent = get_parent_expr(cx, e);
if let Some(p) = parent {
if let ExprAssign(ref target, _) = p.node {
if SpanlessEq::new(cx).eq_expr(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.tables.expr_ty(e)), &paths::STRING)
}
fn is_add(cx: &LateContext, src: &Expr, target: &Expr) -> bool {
match src.node {
ExprBinary(Spanned { node: BiAdd, .. }, ref left, _) => SpanlessEq::new(cx).eq_expr(target, left),
ExprBlock(ref block) => {
block.stmts.is_empty()
&& block
.expr
.as_ref()
.map_or(false, |expr| is_add(cx, expr, target))
},
_ => false,
}
}
#[derive(Copy, Clone)]
pub struct StringLitAsBytes;
impl LintPass for StringLitAsBytes {
fn get_lints(&self) -> LintArray {
lint_array!(STRING_LIT_AS_BYTES)
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for StringLitAsBytes {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
use syntax::ast::LitKind;
use utils::{in_macro, snippet};
if let ExprMethodCall(ref path, _, ref args) = e.node {
if path.name == "as_bytes" {
if let ExprLit(ref lit) = args[0].node {
if let LitKind::Str(ref lit_content, _) = lit.node {
if lit_content.as_str().chars().all(|c| c.is_ascii()) && !in_macro(args[0].span) {
span_lint_and_sugg(
cx,
STRING_LIT_AS_BYTES,
e.span,
"calling `as_bytes()` on a string literal",
"consider using a byte string literal instead",
format!("b{}", snippet(cx, args[0].span, r#""foo""#)),
);
}
}
}
}
}
}
}