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Fix string_lit_as_bytes lint for macros

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Prior to this change, string_lit_as_bytes would trigger for constructs
like `include_str!("filename").as_bytes()` and would recommend fixing it
by rewriting as `binclude_str!("filename")`.

This change updates the lint to act as an EarlyLintPass lint. It then
differentiates between string literals and macros that have bytes
yielding alternatives.

Closes #3205
This commit is contained in:
Jane Lusby 2018-10-05 09:06:05 -07:00
parent 457e7f12e9
commit c209fc9349
3 changed files with 36 additions and 23 deletions
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39
clippy_lints/src/strings.rs
View File

@ -92,7 +92,14 @@ impl LintPass for StringAdd {
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for StringAdd {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
if let ExprKind::Binary(Spanned { node: BinOpKind::Add, .. }, ref left, _) = e.node {
if let ExprKind::Binary(
Spanned {
node: BinOpKind::Add, ..
},
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);
@ -132,13 +139,15 @@ fn is_string(cx: &LateContext<'_, '_>, e: &Expr) -> bool {
fn is_add(cx: &LateContext<'_, '_>, src: &Expr, target: &Expr) -> bool {
match src.node {
ExprKind::Binary(Spanned { node: BinOpKind::Add, .. }, ref left, _) => SpanlessEq::new(cx).eq_expr(target, left),
ExprKind::Binary(
Spanned {
node: BinOpKind::Add, ..
},
ref left,
_,
) => SpanlessEq::new(cx).eq_expr(target, left),
ExprKind::Block(ref block, _) => {
block.stmts.is_empty()
&& block
.expr
.as_ref()
.map_or(false, |expr| is_add(cx, expr, target))
block.stmts.is_empty() && block.expr.as_ref().map_or(false, |expr| is_add(cx, expr, target))
},
_ => false,
}
@ -162,7 +171,21 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for StringLitAsBytes {
if path.ident.name == "as_bytes" {
if let ExprKind::Lit(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) {
let callsite = snippet(cx, args[0].span.source_callsite(), "");
let expanded = format!("\"{}\"", lit_content.as_str());
if callsite.starts_with("include_str!") {
span_lint_and_sugg(
cx,
STRING_LIT_AS_BYTES,
e.span,
"calling `as_bytes()` on `include_str!(..)`",
"consider using `include_bytes!(..)` instead",
snippet(cx, args[0].span, r#""foo""#).replacen("include_str", "include_bytes", 1),
);
} else if callsite == expanded
&& lit_content.as_str().chars().all(|c| c.is_ascii())
&& !in_macro(args[0].span)
{
span_lint_and_sugg(
cx,
STRING_LIT_AS_BYTES,

8
tests/ui/strings.rs
View File

@ -10,10 +10,10 @@
#[warn(clippy::string_add)]
#[allow(clippy::string_add_assign)]
fn add_only() { // ignores assignment distinction
fn add_only() {
// ignores assignment distinction
let mut x = "".to_owned();
for _ in 1..3 {
@ -63,6 +63,8 @@ fn str_lit_as_bytes() {
let ubs = "☃".as_bytes();
let strify = stringify!(foobar).as_bytes();
let includestr = include_str!("entry.rs").as_bytes();
}
fn main() {
@ -72,6 +74,6 @@ fn main() {
// the add is only caught for `String`
let mut x = 1;
; x = x + 1;
; x = x + 1;
assert_eq!(2, x);
}

12
tests/ui/strings.stderr
View File

@ -60,17 +60,5 @@ error: calling `as_bytes()` on a string literal
|
= note: `-D clippy::string-lit-as-bytes` implied by `-D warnings`
error: calling `as_bytes()` on a string literal
--> $DIR/strings.rs:65:18
|
65 | let strify = stringify!(foobar).as_bytes();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using a byte string literal instead: `bstringify!(foobar)`
error: manual implementation of an assign operation
--> $DIR/strings.rs:75:7
|
75 | ; x = x + 1;
| ^^^^^^^^^ help: replace it with: `x += 1`
error: aborting due to 11 previous errors