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use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::source::snippet_with_applicability;
use rustc_errors::Applicability;
use rustc_hir::{Item, ItemKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::{BytePos, Pos};
use rustc_target::spec::abi::Abi;
declare_clippy_lint! {
/// ### What it does
/// Checks for Rust ABI functions with the `#[no_mangle]` attribute.
///
/// ### Why is this bad?
/// The Rust ABI is not stable, but in many simple cases matches
/// enough with the C ABI that it is possible to forget to add
/// `extern "C"` to a function called from C. Changes to the
/// Rust ABI can break this at any point.
///
/// ### Example
/// ```rust
/// #[no_mangle]
/// fn example(arg_one: u32, arg_two: usize) {}
/// ```
///
/// Use instead:
/// ```rust
/// #[no_mangle]
/// extern "C" fn example(arg_one: u32, arg_two: usize) {}
/// ```
#[clippy::version = "1.69.0"]
pub NO_MANGLE_WITH_RUST_ABI,
pedantic,
"convert Rust ABI functions to C ABI"
}
declare_lint_pass!(NoMangleWithRustAbi => [NO_MANGLE_WITH_RUST_ABI]);
impl<'tcx> LateLintPass<'tcx> for NoMangleWithRustAbi {
fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
if let ItemKind::Fn(fn_sig, _, _) = &item.kind {
let attrs = cx.tcx.hir().attrs(item.hir_id());
let mut app = Applicability::MaybeIncorrect;
let snippet = snippet_with_applicability(cx, fn_sig.span, "..", &mut app);
for attr in attrs {
if let Some(ident) = attr.ident()
&& ident.name == rustc_span::sym::no_mangle
&& fn_sig.header.abi == Abi::Rust
&& let Some((fn_attrs, _)) = snippet.split_once("fn")
&& !fn_attrs.contains("extern")
{
let sugg_span = fn_sig.span
.with_lo(fn_sig.span.lo() + BytePos::from_usize(fn_attrs.len()))
.shrink_to_lo();
span_lint_and_then(
cx,
NO_MANGLE_WITH_RUST_ABI,
fn_sig.span,
"`#[no_mangle]` set on a function with the default (`Rust`) ABI",
|diag| {
diag.span_suggestion(sugg_span, "set an ABI", "extern \"C\" ", app)
.span_suggestion(sugg_span, "or explicitly set the default", "extern \"Rust\" ", app);
},
);
}
}
}
}
}
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