rust/clippy_lints/src/assertions_on_constants.rs

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use clippy_utils::consts::{constant, Constant};
use clippy_utils::diagnostics::span_lint_and_help;
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use clippy_utils::higher;
use clippy_utils::source::snippet_opt;
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use clippy_utils::{is_direct_expn_of, is_expn_of, match_panic_call, peel_blocks};
use if_chain::if_chain;
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use rustc_hir::{Expr, ExprKind, UnOp};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
/// ### What it does
/// Checks for `assert!(true)` and `assert!(false)` calls.
///
/// ### Why is this bad?
/// Will be optimized out by the compiler or should probably be replaced by a
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/// `panic!()` or `unreachable!()`
///
/// ### Known problems
/// None
///
/// ### Example
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/// ```rust,ignore
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/// assert!(false)
/// assert!(true)
/// const B: bool = false;
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/// assert!(B)
/// ```
Added `clippy::version` attribute to all normal lints So, some context for this, well, more a story. I'm not used to scripting, I've never really scripted anything, even if it's a valuable skill. I just never really needed it. Now, `@flip1995` correctly suggested using a script for this in `rust-clippy#7813`... And I decided to write a script using nushell because why not? This was a mistake... I spend way more time on this than I would like to admit. It has definitely been more than 4 hours. It shouldn't take that long, but me being new to scripting and nushell just wasn't a good mixture... Anyway, here is the script that creates another script which adds the versions. Fun... Just execute this on the `gh-pages` branch and the resulting `replacer.sh` in `clippy_lints` and it should all work. ```nu mv v0.0.212 rust-1.00.0; mv beta rust-1.57.0; mv master rust-1.58.0; let paths = (open ./rust-1.58.0/lints.json | select id id_span | flatten | select id path); let versions = ( ls | where name =~ "rust-" | select name | format {name}/lints.json | each { open $it | select id | insert version $it | str substring "5,11" version} | group-by id | rotate counter-clockwise id version | update version {get version | first 1} | flatten | select id version); $paths | each { |row| let version = ($versions | where id == ($row.id) | format {version}) let idu = ($row.id | str upcase) $"sed -i '0,/($idu),/{s/pub ($idu),/#[clippy::version = "($version)"]\n pub ($idu),/}' ($row.path)" } | str collect ";" | str find-replace --all '1.00.0' 'pre 1.29.0' | save "replacer.sh"; ``` And this still has some problems, but at this point I just want to be done -.-
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#[clippy::version = "1.34.0"]
pub ASSERTIONS_ON_CONSTANTS,
style,
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"`assert!(true)` / `assert!(false)` will be optimized out by the compiler, and should probably be replaced by a `panic!()` or `unreachable!()`"
}
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declare_lint_pass!(AssertionsOnConstants => [ASSERTIONS_ON_CONSTANTS]);
impl<'tcx> LateLintPass<'tcx> for AssertionsOnConstants {
fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
let lint_true = |is_debug: bool| {
span_lint_and_help(
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cx,
ASSERTIONS_ON_CONSTANTS,
e.span,
if is_debug {
"`debug_assert!(true)` will be optimized out by the compiler"
} else {
"`assert!(true)` will be optimized out by the compiler"
},
None,
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"remove it",
);
};
let lint_false_without_message = || {
span_lint_and_help(
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cx,
ASSERTIONS_ON_CONSTANTS,
e.span,
"`assert!(false)` should probably be replaced",
None,
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"use `panic!()` or `unreachable!()`",
);
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};
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let lint_false_with_message = |panic_message: String| {
span_lint_and_help(
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cx,
ASSERTIONS_ON_CONSTANTS,
e.span,
&format!("`assert!(false, {})` should probably be replaced", panic_message),
None,
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&format!("use `panic!({})` or `unreachable!({})`", panic_message, panic_message),
);
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};
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if let Some(debug_assert_span) = is_expn_of(e.span, "debug_assert") {
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if debug_assert_span.from_expansion() {
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return;
}
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if_chain! {
if let ExprKind::Unary(_, lit) = e.kind;
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if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.typeck_results(), lit);
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if is_true;
then {
lint_true(true);
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}
};
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} else if let Some(assert_span) = is_direct_expn_of(e.span, "assert") {
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if assert_span.from_expansion() {
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return;
}
if let Some(assert_match) = match_assert_with_message(cx, e) {
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match assert_match {
// matched assert but not message
AssertKind::WithoutMessage(false) => lint_false_without_message(),
AssertKind::WithoutMessage(true) | AssertKind::WithMessage(_, true) => lint_true(false),
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AssertKind::WithMessage(panic_message, false) => lint_false_with_message(panic_message),
};
}
}
}
}
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/// Result of calling `match_assert_with_message`.
enum AssertKind {
WithMessage(String, bool),
WithoutMessage(bool),
}
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/// Check if the expression matches
///
/// ```rust,ignore
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/// if !c {
/// {
/// ::std::rt::begin_panic(message, _)
/// }
/// }
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/// ```
///
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/// where `message` is any expression and `c` is a constant bool.
fn match_assert_with_message<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<AssertKind> {
if_chain! {
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if let Some(higher::If { cond, then, .. }) = higher::If::hir(expr);
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if let ExprKind::Unary(UnOp::Not, expr) = cond.kind;
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// bind the first argument of the `assert!` macro
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if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.typeck_results(), expr);
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let begin_panic_call = peel_blocks(then);
// function call
if let Some(arg) = match_panic_call(cx, begin_panic_call);
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// bind the second argument of the `assert!` macro if it exists
if let panic_message = snippet_opt(cx, arg.span);
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// second argument of begin_panic is irrelevant
// as is the second match arm
then {
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// an empty message occurs when it was generated by the macro
// (and not passed by the user)
return panic_message
.filter(|msg| !msg.is_empty())
.map(|msg| AssertKind::WithMessage(msg, is_true))
.or(Some(AssertKind::WithoutMessage(is_true)));
}
}
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None
}