3a68217f49
Remove overlapping parts of multipart suggestions This PR adds a debug assertion that the parts of a single substitution cannot overlap, fixes a overlapping substitution from the testsuite, and fixes https://github.com/rust-lang/rust/issues/106870. Note that a single suggestion can still have multiple overlapping substitutions / possible edits, we just don't suggest overlapping replacements in a single edit anymore. I've also included a fix for an unrelated bug where rustfix for `explicit_outlives_requirements` would produce multiple trailing commas for a where clause.
468 lines
16 KiB
Rust
468 lines
16 KiB
Rust
use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
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use clippy_utils::is_diag_trait_item;
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use clippy_utils::macros::FormatParamKind::{Implicit, Named, NamedInline, Numbered, Starred};
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use clippy_utils::macros::{
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is_assert_macro, is_format_macro, is_panic, root_macro_call, Count, FormatArg, FormatArgsExpn, FormatParam,
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FormatParamUsage,
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};
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use clippy_utils::msrvs::{self, Msrv};
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use clippy_utils::source::snippet_opt;
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use clippy_utils::ty::{implements_trait, is_type_lang_item};
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use if_chain::if_chain;
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use itertools::Itertools;
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use rustc_errors::{
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Applicability,
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SuggestionStyle::{CompletelyHidden, ShowCode},
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};
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use rustc_hir::{Expr, ExprKind, HirId, LangItem, QPath};
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use rustc_lint::{LateContext, LateLintPass, LintContext};
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use rustc_middle::ty::adjustment::{Adjust, Adjustment};
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use rustc_middle::ty::Ty;
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use rustc_session::{declare_tool_lint, impl_lint_pass};
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use rustc_span::def_id::DefId;
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use rustc_span::edition::Edition::Edition2021;
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use rustc_span::{sym, ExpnData, ExpnKind, Span, Symbol};
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declare_clippy_lint! {
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/// ### What it does
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/// Detects `format!` within the arguments of another macro that does
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/// formatting such as `format!` itself, `write!` or `println!`. Suggests
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/// inlining the `format!` call.
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///
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/// ### Why is this bad?
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/// The recommended code is both shorter and avoids a temporary allocation.
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///
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/// ### Example
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/// ```rust
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/// # use std::panic::Location;
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/// println!("error: {}", format!("something failed at {}", Location::caller()));
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/// ```
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/// Use instead:
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/// ```rust
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/// # use std::panic::Location;
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/// println!("error: something failed at {}", Location::caller());
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/// ```
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#[clippy::version = "1.58.0"]
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pub FORMAT_IN_FORMAT_ARGS,
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perf,
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"`format!` used in a macro that does formatting"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for [`ToString::to_string`](https://doc.rust-lang.org/std/string/trait.ToString.html#tymethod.to_string)
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/// applied to a type that implements [`Display`](https://doc.rust-lang.org/std/fmt/trait.Display.html)
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/// in a macro that does formatting.
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///
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/// ### Why is this bad?
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/// Since the type implements `Display`, the use of `to_string` is
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/// unnecessary.
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///
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/// ### Example
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/// ```rust
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/// # use std::panic::Location;
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/// println!("error: something failed at {}", Location::caller().to_string());
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/// ```
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/// Use instead:
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/// ```rust
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/// # use std::panic::Location;
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/// println!("error: something failed at {}", Location::caller());
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/// ```
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#[clippy::version = "1.58.0"]
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pub TO_STRING_IN_FORMAT_ARGS,
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perf,
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"`to_string` applied to a type that implements `Display` in format args"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Detect when a variable is not inlined in a format string,
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/// and suggests to inline it.
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///
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/// ### Why is this bad?
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/// Non-inlined code is slightly more difficult to read and understand,
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/// as it requires arguments to be matched against the format string.
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/// The inlined syntax, where allowed, is simpler.
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///
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/// ### Example
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/// ```rust
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/// # let var = 42;
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/// # let width = 1;
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/// # let prec = 2;
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/// format!("{}", var);
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/// format!("{v:?}", v = var);
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/// format!("{0} {0}", var);
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/// format!("{0:1$}", var, width);
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/// format!("{:.*}", prec, var);
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/// ```
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/// Use instead:
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/// ```rust
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/// # let var = 42;
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/// # let width = 1;
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/// # let prec = 2;
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/// format!("{var}");
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/// format!("{var:?}");
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/// format!("{var} {var}");
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/// format!("{var:width$}");
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/// format!("{var:.prec$}");
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/// ```
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///
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/// If allow-mixed-uninlined-format-args is set to false in clippy.toml,
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/// the following code will also trigger the lint:
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/// ```rust
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/// # let var = 42;
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/// format!("{} {}", var, 1+2);
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/// ```
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/// Use instead:
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/// ```rust
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/// # let var = 42;
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/// format!("{var} {}", 1+2);
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/// ```
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///
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/// ### Known Problems
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///
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/// If a format string contains a numbered argument that cannot be inlined
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/// nothing will be suggested, e.g. `println!("{0}={1}", var, 1+2)`.
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#[clippy::version = "1.66.0"]
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pub UNINLINED_FORMAT_ARGS,
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style,
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"using non-inlined variables in `format!` calls"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Detects [formatting parameters] that have no effect on the output of
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/// `format!()`, `println!()` or similar macros.
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///
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/// ### Why is this bad?
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/// Shorter format specifiers are easier to read, it may also indicate that
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/// an expected formatting operation such as adding padding isn't happening.
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///
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/// ### Example
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/// ```rust
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/// println!("{:.}", 1.0);
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///
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/// println!("not padded: {:5}", format_args!("..."));
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/// ```
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/// Use instead:
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/// ```rust
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/// println!("{}", 1.0);
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///
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/// println!("not padded: {}", format_args!("..."));
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/// // OR
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/// println!("padded: {:5}", format!("..."));
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/// ```
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///
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/// [formatting parameters]: https://doc.rust-lang.org/std/fmt/index.html#formatting-parameters
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#[clippy::version = "1.66.0"]
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pub UNUSED_FORMAT_SPECS,
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complexity,
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"use of a format specifier that has no effect"
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}
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impl_lint_pass!(FormatArgs => [
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FORMAT_IN_FORMAT_ARGS,
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TO_STRING_IN_FORMAT_ARGS,
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UNINLINED_FORMAT_ARGS,
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UNUSED_FORMAT_SPECS,
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]);
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pub struct FormatArgs {
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msrv: Msrv,
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ignore_mixed: bool,
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}
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impl FormatArgs {
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#[must_use]
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pub fn new(msrv: Msrv, allow_mixed_uninlined_format_args: bool) -> Self {
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Self {
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msrv,
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ignore_mixed: allow_mixed_uninlined_format_args,
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}
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}
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}
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impl<'tcx> LateLintPass<'tcx> for FormatArgs {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
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if let Some(format_args) = FormatArgsExpn::parse(cx, expr)
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&& let expr_expn_data = expr.span.ctxt().outer_expn_data()
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&& let outermost_expn_data = outermost_expn_data(expr_expn_data)
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&& let Some(macro_def_id) = outermost_expn_data.macro_def_id
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&& is_format_macro(cx, macro_def_id)
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&& let ExpnKind::Macro(_, name) = outermost_expn_data.kind
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{
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for arg in &format_args.args {
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check_unused_format_specifier(cx, arg);
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if !arg.format.is_default() {
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continue;
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}
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if is_aliased(&format_args, arg.param.value.hir_id) {
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continue;
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}
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check_format_in_format_args(cx, outermost_expn_data.call_site, name, arg.param.value);
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check_to_string_in_format_args(cx, name, arg.param.value);
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}
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if self.msrv.meets(msrvs::FORMAT_ARGS_CAPTURE) {
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check_uninlined_args(cx, &format_args, outermost_expn_data.call_site, macro_def_id, self.ignore_mixed);
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}
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}
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}
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extract_msrv_attr!(LateContext);
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}
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fn check_unused_format_specifier(cx: &LateContext<'_>, arg: &FormatArg<'_>) {
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let param_ty = cx.typeck_results().expr_ty(arg.param.value).peel_refs();
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if let Count::Implied(Some(mut span)) = arg.format.precision
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&& !span.is_empty()
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{
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span_lint_and_then(
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cx,
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UNUSED_FORMAT_SPECS,
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span,
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"empty precision specifier has no effect",
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|diag| {
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if param_ty.is_floating_point() {
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diag.note("a precision specifier is not required to format floats");
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}
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if arg.format.is_default() {
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// If there's no other specifiers remove the `:` too
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span = arg.format_span();
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}
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diag.span_suggestion_verbose(span, "remove the `.`", "", Applicability::MachineApplicable);
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},
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);
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}
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if is_type_lang_item(cx, param_ty, LangItem::FormatArguments) && !arg.format.is_default_for_trait() {
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span_lint_and_then(
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cx,
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UNUSED_FORMAT_SPECS,
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arg.span,
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"format specifiers have no effect on `format_args!()`",
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|diag| {
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let mut suggest_format = |spec, span| {
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let message = format!("for the {spec} to apply consider using `format!()`");
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if let Some(mac_call) = root_macro_call(arg.param.value.span)
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&& cx.tcx.is_diagnostic_item(sym::format_args_macro, mac_call.def_id)
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&& arg.span.eq_ctxt(mac_call.span)
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{
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diag.span_suggestion(
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cx.sess().source_map().span_until_char(mac_call.span, '!'),
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message,
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"format",
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Applicability::MaybeIncorrect,
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);
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} else if let Some(span) = span {
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diag.span_help(span, message);
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}
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};
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if !arg.format.width.is_implied() {
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suggest_format("width", arg.format.width.span());
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}
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if !arg.format.precision.is_implied() {
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suggest_format("precision", arg.format.precision.span());
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}
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diag.span_suggestion_verbose(
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arg.format_span(),
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"if the current behavior is intentional, remove the format specifiers",
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"",
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Applicability::MaybeIncorrect,
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);
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},
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);
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}
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}
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fn check_uninlined_args(
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cx: &LateContext<'_>,
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args: &FormatArgsExpn<'_>,
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call_site: Span,
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def_id: DefId,
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ignore_mixed: bool,
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) {
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if args.format_string.span.from_expansion() {
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return;
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}
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if call_site.edition() < Edition2021 && (is_panic(cx, def_id) || is_assert_macro(cx, def_id)) {
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// panic!, assert!, and debug_assert! before 2021 edition considers a single string argument as
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// non-format
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return;
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}
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let mut fixes = Vec::new();
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// If any of the arguments are referenced by an index number,
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// and that argument is not a simple variable and cannot be inlined,
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// we cannot remove any other arguments in the format string,
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// because the index numbers might be wrong after inlining.
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// Example of an un-inlinable format: print!("{}{1}", foo, 2)
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if !args.params().all(|p| check_one_arg(args, &p, &mut fixes, ignore_mixed)) || fixes.is_empty() {
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return;
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}
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// multiline span display suggestion is sometimes broken: https://github.com/rust-lang/rust/pull/102729#discussion_r988704308
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// in those cases, make the code suggestion hidden
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let multiline_fix = fixes.iter().any(|(span, _)| cx.sess().source_map().is_multiline(*span));
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// Suggest removing each argument only once, for example in `format!("{0} {0}", arg)`.
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fixes.sort_unstable_by_key(|(span, _)| *span);
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fixes.dedup_by_key(|(span, _)| *span);
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span_lint_and_then(
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cx,
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UNINLINED_FORMAT_ARGS,
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call_site,
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"variables can be used directly in the `format!` string",
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|diag| {
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diag.multipart_suggestion_with_style(
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"change this to",
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fixes,
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Applicability::MachineApplicable,
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if multiline_fix { CompletelyHidden } else { ShowCode },
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);
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},
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);
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}
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fn check_one_arg(
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args: &FormatArgsExpn<'_>,
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param: &FormatParam<'_>,
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fixes: &mut Vec<(Span, String)>,
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ignore_mixed: bool,
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) -> bool {
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if matches!(param.kind, Implicit | Starred | Named(_) | Numbered)
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&& let ExprKind::Path(QPath::Resolved(None, path)) = param.value.kind
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&& let [segment] = path.segments
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&& let Some(arg_span) = args.value_with_prev_comma_span(param.value.hir_id)
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{
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let replacement = match param.usage {
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FormatParamUsage::Argument => segment.ident.name.to_string(),
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FormatParamUsage::Width => format!("{}$", segment.ident.name),
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FormatParamUsage::Precision => format!(".{}$", segment.ident.name),
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};
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fixes.push((param.span, replacement));
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fixes.push((arg_span, String::new()));
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true // successful inlining, continue checking
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} else {
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// Do not continue inlining (return false) in case
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// * if we can't inline a numbered argument, e.g. `print!("{0} ...", foo.bar, ...)`
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// * if allow_mixed_uninlined_format_args is false and this arg hasn't been inlined already
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param.kind != Numbered && (!ignore_mixed || matches!(param.kind, NamedInline(_)))
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}
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}
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fn outermost_expn_data(expn_data: ExpnData) -> ExpnData {
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if expn_data.call_site.from_expansion() {
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outermost_expn_data(expn_data.call_site.ctxt().outer_expn_data())
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} else {
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expn_data
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}
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}
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fn check_format_in_format_args(
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cx: &LateContext<'_>,
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call_site: Span,
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name: Symbol,
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arg: &Expr<'_>,
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) {
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let expn_data = arg.span.ctxt().outer_expn_data();
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if expn_data.call_site.from_expansion() {
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return;
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}
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let Some(mac_id) = expn_data.macro_def_id else { return };
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if !cx.tcx.is_diagnostic_item(sym::format_macro, mac_id) {
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return;
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}
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span_lint_and_then(
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cx,
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FORMAT_IN_FORMAT_ARGS,
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call_site,
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&format!("`format!` in `{name}!` args"),
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|diag| {
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diag.help(format!(
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"combine the `format!(..)` arguments with the outer `{name}!(..)` call"
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));
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diag.help("or consider changing `format!` to `format_args!`");
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},
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);
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}
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fn check_to_string_in_format_args(cx: &LateContext<'_>, name: Symbol, value: &Expr<'_>) {
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if_chain! {
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if !value.span.from_expansion();
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if let ExprKind::MethodCall(_, receiver, [], to_string_span) = value.kind;
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if let Some(method_def_id) = cx.typeck_results().type_dependent_def_id(value.hir_id);
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if is_diag_trait_item(cx, method_def_id, sym::ToString);
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let receiver_ty = cx.typeck_results().expr_ty(receiver);
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if let Some(display_trait_id) = cx.tcx.get_diagnostic_item(sym::Display);
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let (n_needed_derefs, target) =
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count_needed_derefs(receiver_ty, cx.typeck_results().expr_adjustments(receiver).iter());
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if implements_trait(cx, target, display_trait_id, &[]);
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if let Some(sized_trait_id) = cx.tcx.lang_items().sized_trait();
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if let Some(receiver_snippet) = snippet_opt(cx, receiver.span);
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then {
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let needs_ref = !implements_trait(cx, receiver_ty, sized_trait_id, &[]);
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if n_needed_derefs == 0 && !needs_ref {
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span_lint_and_sugg(
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cx,
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TO_STRING_IN_FORMAT_ARGS,
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to_string_span.with_lo(receiver.span.hi()),
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&format!(
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"`to_string` applied to a type that implements `Display` in `{name}!` args"
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),
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"remove this",
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String::new(),
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Applicability::MachineApplicable,
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);
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} else {
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span_lint_and_sugg(
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cx,
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TO_STRING_IN_FORMAT_ARGS,
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value.span,
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&format!(
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"`to_string` applied to a type that implements `Display` in `{name}!` args"
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),
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|
"use this",
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format!(
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"{}{:*>n_needed_derefs$}{receiver_snippet}",
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if needs_ref { "&" } else { "" },
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""
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),
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Applicability::MachineApplicable,
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);
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}
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}
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}
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}
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|
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/// Returns true if `hir_id` is referred to by multiple format params
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fn is_aliased(args: &FormatArgsExpn<'_>, hir_id: HirId) -> bool {
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args.params().filter(|param| param.value.hir_id == hir_id).at_most_one().is_err()
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}
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fn count_needed_derefs<'tcx, I>(mut ty: Ty<'tcx>, mut iter: I) -> (usize, Ty<'tcx>)
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where
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I: Iterator<Item = &'tcx Adjustment<'tcx>>,
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{
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let mut n_total = 0;
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let mut n_needed = 0;
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loop {
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if let Some(Adjustment { kind: Adjust::Deref(overloaded_deref), target }) = iter.next() {
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n_total += 1;
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if overloaded_deref.is_some() {
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n_needed = n_total;
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}
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ty = *target;
|
|
} else {
|
|
return (n_needed, ty);
|
|
}
|
|
}
|
|
}
|