-use crate::utils::{is_entrypoint_fn, span_lint, trait_ref_of_method};
-use rustc::hir;
-use rustc::hir::intravisit::FnKind;
-use rustc::hir::{Body, Constness, FnDecl, HirId};
-use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintPass};
-use rustc::{declare_lint_pass, declare_tool_lint};
+use crate::utils::{has_drop, is_entrypoint_fn, span_lint, trait_ref_of_method};
+use rustc::lint::in_external_macro;
+use rustc_hir as hir;
+use rustc_hir::intravisit::FnKind;
+use rustc_hir::{Body, Constness, FnDecl, HirId};
+use rustc_lint::{LateContext, LateLintPass};
use rustc_mir::transform::qualify_min_const_fn::is_min_const_fn;
-use syntax_pos::Span;
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::Span;
+use rustc_typeck::hir_ty_to_ty;
declare_clippy_lint! {
/// **What it does:**
/// **Example:**
///
/// ```rust
+ /// # struct Foo {
+ /// # random_number: usize,
+ /// # }
+ /// # impl Foo {
/// fn new() -> Self {
/// Self { random_number: 42 }
/// }
+ /// # }
/// ```
///
/// Could be a const fn:
///
/// ```rust
+ /// # struct Foo {
+ /// # random_number: usize,
+ /// # }
+ /// # impl Foo {
/// const fn new() -> Self {
/// Self { random_number: 42 }
/// }
+ /// # }
/// ```
pub MISSING_CONST_FOR_FN,
nursery,
&mut self,
cx: &LateContext<'_, '_>,
kind: FnKind<'_>,
- _: &FnDecl,
- _: &Body,
+ _: &FnDecl<'_>,
+ _: &Body<'_>,
span: Span,
hir_id: HirId,
) {
- let def_id = cx.tcx.hir().local_def_id_from_hir_id(hir_id);
+ let def_id = cx.tcx.hir().local_def_id(hir_id);
if in_external_macro(cx.tcx.sess, span) || is_entrypoint_fn(cx, def_id) {
return;
}
},
FnKind::Method(_, sig, ..) => {
- if trait_ref_of_method(cx, hir_id).is_some() || already_const(sig.header) {
+ if trait_ref_of_method(cx, hir_id).is_some()
+ || already_const(sig.header)
+ || method_accepts_dropable(cx, sig.decl.inputs)
+ {
return;
}
},
let mir = cx.tcx.optimized_mir(def_id);
if let Err((span, err)) = is_min_const_fn(cx.tcx, def_id, &mir) {
- if cx.tcx.is_min_const_fn(def_id) {
+ if rustc_mir::const_eval::is_min_const_fn(cx.tcx, def_id) {
cx.tcx.sess.span_err(span, &err);
}
} else {
- span_lint(cx, MISSING_CONST_FOR_FN, span, "this could be a const_fn");
+ span_lint(cx, MISSING_CONST_FOR_FN, span, "this could be a `const fn`");
}
}
}
+/// Returns true if any of the method parameters is a type that implements `Drop`. The method
+/// can't be made const then, because `drop` can't be const-evaluated.
+fn method_accepts_dropable(cx: &LateContext<'_, '_>, param_tys: &[hir::Ty<'_>]) -> bool {
+ // If any of the params are dropable, return true
+ param_tys.iter().any(|hir_ty| {
+ let ty_ty = hir_ty_to_ty(cx.tcx, hir_ty);
+ has_drop(cx, ty_ty)
+ })
+}
+
// We don't have to lint on something that's already `const`
+#[must_use]
fn already_const(header: hir::FnHeader) -> bool {
header.constness == Constness::Const
}