2018-12-29 15:04:45 +00:00
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use rustc_errors::Applicability;
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2020-02-21 08:39:38 +00:00
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use rustc_hir::{BinOpKind, Expr, ExprKind};
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2020-01-12 06:08:41 +00:00
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use rustc_lint::{LateContext, LateLintPass, LintContext};
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2020-03-30 09:02:14 +00:00
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use rustc_middle::lint::in_external_macro;
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2020-01-11 11:37:08 +00:00
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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2020-01-04 10:00:00 +00:00
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use rustc_span::source_map::Spanned;
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2015-08-05 13:10:45 +00:00
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2019-11-11 22:42:12 +00:00
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use if_chain::if_chain;
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2019-05-14 08:06:21 +00:00
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use crate::utils::SpanlessEq;
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2020-04-23 06:09:42 +00:00
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use crate::utils::{get_parent_expr, is_allowed, is_type_diagnostic_item, span_lint, span_lint_and_sugg, walk_ptrs_ty};
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2019-01-31 01:15:29 +00:00
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2018-03-28 13:24:26 +00:00
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declare_clippy_lint! {
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2019-03-05 16:50:33 +00:00
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/// **What it does:** Checks for string appends of the form `x = x + y` (without
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/// `let`!).
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///
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/// **Why is this bad?** It's not really bad, but some people think that the
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/// `.push_str(_)` method is more readable.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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///
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/// ```rust
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/// let mut x = "Hello".to_owned();
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/// x = x + ", World";
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2020-06-09 14:36:01 +00:00
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///
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/// // More readable
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/// x += ", World";
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/// x.push_str(", World");
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2019-03-05 16:50:33 +00:00
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/// ```
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2015-08-05 13:10:45 +00:00
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pub STRING_ADD_ASSIGN,
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2018-03-28 13:24:26 +00:00
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pedantic,
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2016-08-06 08:18:36 +00:00
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"using `x = x + ..` where x is a `String` instead of `push_str()`"
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2015-08-05 13:10:45 +00:00
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}
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2018-03-28 13:24:26 +00:00
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declare_clippy_lint! {
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2019-03-05 16:50:33 +00:00
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/// **What it does:** Checks for all instances of `x + _` where `x` is of type
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/// `String`, but only if [`string_add_assign`](#string_add_assign) does *not*
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/// match.
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///
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/// **Why is this bad?** It's not bad in and of itself. However, this particular
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/// `Add` implementation is asymmetric (the other operand need not be `String`,
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/// but `x` does), while addition as mathematically defined is symmetric, also
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/// the `String::push_str(_)` function is a perfectly good replacement.
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2019-01-31 01:15:29 +00:00
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/// Therefore, some dislike it and wish not to have it in their code.
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2019-03-05 16:50:33 +00:00
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///
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/// That said, other people think that string addition, having a long tradition
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/// in other languages is actually fine, which is why we decided to make this
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/// particular lint `allow` by default.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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///
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/// ```rust
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/// let x = "Hello".to_owned();
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2019-08-03 19:24:50 +00:00
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/// x + ", World";
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2019-03-05 16:50:33 +00:00
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/// ```
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2015-08-12 13:57:50 +00:00
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pub STRING_ADD,
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2018-03-28 13:24:26 +00:00
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restriction,
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2016-08-06 08:18:36 +00:00
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"using `x + ..` where x is a `String` instead of `push_str()`"
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2015-08-12 13:50:56 +00:00
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}
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2018-03-28 13:24:26 +00:00
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declare_clippy_lint! {
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2019-03-05 16:50:33 +00:00
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/// **What it does:** Checks for the `as_bytes` method called on string literals
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/// that contain only ASCII characters.
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///
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2019-01-31 01:15:29 +00:00
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/// **Why is this bad?** Byte string literals (e.g., `b"foo"`) can be used
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2019-03-05 16:50:33 +00:00
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/// instead. They are shorter but less discoverable than `as_bytes()`.
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///
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/// **Known Problems:** None.
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///
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/// **Example:**
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/// ```rust
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2020-06-09 14:36:01 +00:00
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/// // Bad
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2019-03-05 16:50:33 +00:00
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/// let bs = "a byte string".as_bytes();
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2020-06-09 14:36:01 +00:00
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///
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/// // Good
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/// let bs = b"a byte string";
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2019-03-05 16:50:33 +00:00
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/// ```
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2016-01-19 18:14:49 +00:00
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pub STRING_LIT_AS_BYTES,
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2018-03-28 13:24:26 +00:00
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style,
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2016-08-06 08:18:36 +00:00
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"calling `as_bytes` on a string literal instead of using a byte string literal"
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2016-01-19 18:14:49 +00:00
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}
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2019-04-08 20:43:55 +00:00
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declare_lint_pass!(StringAdd => [STRING_ADD, STRING_ADD_ASSIGN]);
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2015-08-12 13:50:56 +00:00
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2020-06-25 20:41:36 +00:00
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impl<'tcx> LateLintPass<'tcx> for StringAdd {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
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2019-12-05 10:06:13 +00:00
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if in_external_macro(cx.sess(), e.span) {
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2019-12-04 20:50:28 +00:00
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return;
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}
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2018-10-05 16:06:05 +00:00
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if let ExprKind::Binary(
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Spanned {
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node: BinOpKind::Add, ..
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},
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ref left,
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_,
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2019-09-27 15:16:06 +00:00
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) = e.kind
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2018-10-05 16:06:05 +00:00
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{
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2015-08-12 13:57:50 +00:00
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if is_string(cx, left) {
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2019-02-24 18:43:15 +00:00
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if !is_allowed(cx, STRING_ADD_ASSIGN, e.hir_id) {
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2015-08-12 13:57:50 +00:00
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let parent = get_parent_expr(cx, e);
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2016-08-01 14:59:14 +00:00
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if let Some(p) = parent {
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2019-12-24 04:16:04 +00:00
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if let ExprKind::Assign(ref target, _, _) = p.kind {
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2015-08-12 13:57:50 +00:00
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// avoid duplicate matches
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2016-02-06 19:13:25 +00:00
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if SpanlessEq::new(cx).eq_expr(target, left) {
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2016-01-04 04:26:12 +00:00
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return;
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}
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2015-08-12 13:57:50 +00:00
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}
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}
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}
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2017-08-09 07:30:56 +00:00
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span_lint(
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cx,
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STRING_ADD,
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e.span,
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"you added something to a string. Consider using `String::push_str()` instead",
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);
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2015-08-12 13:57:50 +00:00
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}
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2019-12-24 04:16:04 +00:00
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} else if let ExprKind::Assign(ref target, ref src, _) = e.kind {
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2015-08-21 10:19:07 +00:00
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if is_string(cx, target) && is_add(cx, src, target) {
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2017-08-09 07:30:56 +00:00
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span_lint(
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cx,
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STRING_ADD_ASSIGN,
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e.span,
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"you assigned the result of adding something to this string. Consider using \
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2017-09-05 09:33:04 +00:00
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`String::push_str()` instead",
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2017-08-09 07:30:56 +00:00
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);
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2015-08-05 13:10:45 +00:00
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}
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}
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}
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}
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2020-06-25 20:41:36 +00:00
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fn is_string(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
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2020-07-17 08:47:04 +00:00
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is_type_diagnostic_item(cx, walk_ptrs_ty(cx.typeck_results().expr_ty(e)), sym!(string_type))
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2015-08-05 13:10:45 +00:00
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}
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2020-06-25 20:41:36 +00:00
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fn is_add(cx: &LateContext<'_>, src: &Expr<'_>, target: &Expr<'_>) -> bool {
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2019-09-27 15:16:06 +00:00
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match src.kind {
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2018-10-05 16:06:05 +00:00
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ExprKind::Binary(
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Spanned {
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node: BinOpKind::Add, ..
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},
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ref left,
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_,
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) => SpanlessEq::new(cx).eq_expr(target, left),
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2018-07-12 07:30:57 +00:00
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ExprKind::Block(ref block, _) => {
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2018-10-05 16:06:05 +00:00
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block.stmts.is_empty() && block.expr.as_ref().map_or(false, |expr| is_add(cx, expr, target))
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2016-12-20 17:21:30 +00:00
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},
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2016-01-04 04:26:12 +00:00
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_ => false,
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2015-08-05 13:10:45 +00:00
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}
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}
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2016-01-19 18:14:49 +00:00
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2019-07-08 16:12:51 +00:00
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// Max length a b"foo" string can take
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const MAX_LENGTH_BYTE_STRING_LIT: usize = 32;
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2019-04-08 20:43:55 +00:00
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declare_lint_pass!(StringLitAsBytes => [STRING_LIT_AS_BYTES]);
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2016-01-19 18:14:49 +00:00
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2020-06-25 20:41:36 +00:00
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impl<'tcx> LateLintPass<'tcx> for StringLitAsBytes {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
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2019-08-19 16:30:32 +00:00
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use crate::utils::{snippet, snippet_with_applicability};
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2020-03-01 03:23:33 +00:00
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use rustc_ast::ast::LitKind;
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2016-01-19 18:14:49 +00:00
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2019-11-11 22:42:12 +00:00
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if_chain! {
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2020-06-09 21:44:04 +00:00
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if let ExprKind::MethodCall(path, _, args, _) = &e.kind;
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2019-11-11 22:42:12 +00:00
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if path.ident.name == sym!(as_bytes);
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if let ExprKind::Lit(lit) = &args[0].kind;
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if let LitKind::Str(lit_content, _) = &lit.node;
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then {
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let callsite = snippet(cx, args[0].span.source_callsite(), r#""foo""#);
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let mut applicability = Applicability::MachineApplicable;
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if callsite.starts_with("include_str!") {
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span_lint_and_sugg(
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cx,
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STRING_LIT_AS_BYTES,
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e.span,
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"calling `as_bytes()` on `include_str!(..)`",
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"consider using `include_bytes!(..)` instead",
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snippet_with_applicability(cx, args[0].span, r#""foo""#, &mut applicability).replacen(
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"include_str",
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"include_bytes",
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1,
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),
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applicability,
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);
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} else if lit_content.as_str().is_ascii()
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&& lit_content.as_str().len() <= MAX_LENGTH_BYTE_STRING_LIT
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&& !args[0].span.from_expansion()
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{
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span_lint_and_sugg(
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cx,
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STRING_LIT_AS_BYTES,
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e.span,
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"calling `as_bytes()` on a string literal",
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"consider using a byte string literal instead",
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format!(
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"b{}",
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snippet_with_applicability(cx, args[0].span, r#""foo""#, &mut applicability)
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),
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applicability,
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);
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2016-01-19 18:14:49 +00:00
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}
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}
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}
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}
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}
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