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use crate::rustc_lint::LintContext;
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet_with_context;
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::{Block, ExprKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
/// ### What it does
/// Looks for blocks of expressions and fires if the last expression returns
/// `()` but is not followed by a semicolon.
///
/// ### Why is this bad?
/// The semicolon might be optional but when extending the block with new
/// code, it doesn't require a change in previous last line.
///
/// ### Example
/// ```rust
/// fn main() {
/// println!("Hello world")
/// }
/// ```
/// Use instead:
/// ```rust
/// fn main() {
/// println!("Hello world");
/// }
/// ```
#[clippy::version = "1.52.0"]
pub SEMICOLON_IF_NOTHING_RETURNED,
pedantic,
"add a semicolon if nothing is returned"
}
declare_lint_pass!(SemicolonIfNothingReturned => [SEMICOLON_IF_NOTHING_RETURNED]);
impl<'tcx> LateLintPass<'tcx> for SemicolonIfNothingReturned {
fn check_block(&mut self, cx: &LateContext<'tcx>, block: &'tcx Block<'tcx>) {
if_chain! {
if !block.span.from_expansion();
if let Some(expr) = block.expr;
let t_expr = cx.typeck_results().expr_ty(expr);
if t_expr.is_unit();
let mut app = Applicability::MachineApplicable;
if let snippet = snippet_with_context(cx, expr.span, block.span.ctxt(), "}", &mut app).0;
if !snippet.ends_with('}') && !snippet.ends_with(';');
if cx.sess().source_map().is_multiline(block.span);
then {
// filter out the desugared `for` loop
if let ExprKind::DropTemps(..) = &expr.kind {
return;
}
span_lint_and_sugg(
cx,
SEMICOLON_IF_NOTHING_RETURNED,
expr.span.source_callsite(),
"consider adding a `;` to the last statement for consistent formatting",
"add a `;` here",
format!("{snippet};"),
app,
);
}
}
}
}
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