rustc_lint/
enum_intrinsics_non_enums.rs
1use rustc_hir as hir;
2use rustc_middle::ty::{Ty, TypeVisitableExt};
3use rustc_session::{declare_lint, declare_lint_pass};
4use rustc_span::{Span, sym};
5
6use crate::context::LintContext;
7use crate::lints::{EnumIntrinsicsMemDiscriminate, EnumIntrinsicsMemVariant};
8use crate::{LateContext, LateLintPass};
9
10declare_lint! {
11 ENUM_INTRINSICS_NON_ENUMS,
36 Deny,
37 "detects calls to `core::mem::discriminant` and `core::mem::variant_count` with non-enum types"
38}
39
40declare_lint_pass!(EnumIntrinsicsNonEnums => [ENUM_INTRINSICS_NON_ENUMS]);
41
42fn is_non_enum(t: Ty<'_>) -> bool {
45 !t.is_enum() && !t.has_param()
46}
47
48fn enforce_mem_discriminant(
49 cx: &LateContext<'_>,
50 func_expr: &hir::Expr<'_>,
51 expr_span: Span,
52 args_span: Span,
53) {
54 let ty_param = cx.typeck_results().node_args(func_expr.hir_id).type_at(0);
55 if is_non_enum(ty_param) {
56 cx.emit_span_lint(
57 ENUM_INTRINSICS_NON_ENUMS,
58 expr_span,
59 EnumIntrinsicsMemDiscriminate { ty_param, note: args_span },
60 );
61 }
62}
63
64fn enforce_mem_variant_count(cx: &LateContext<'_>, func_expr: &hir::Expr<'_>, span: Span) {
65 let ty_param = cx.typeck_results().node_args(func_expr.hir_id).type_at(0);
66 if is_non_enum(ty_param) {
67 cx.emit_span_lint(ENUM_INTRINSICS_NON_ENUMS, span, EnumIntrinsicsMemVariant { ty_param });
68 }
69}
70
71impl<'tcx> LateLintPass<'tcx> for EnumIntrinsicsNonEnums {
72 fn check_expr(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) {
73 let hir::ExprKind::Call(func, args) = &expr.kind else { return };
74 let hir::ExprKind::Path(qpath) = &func.kind else { return };
75 let Some(def_id) = cx.qpath_res(qpath, func.hir_id).opt_def_id() else { return };
76 let Some(name) = cx.tcx.get_diagnostic_name(def_id) else { return };
77 match name {
78 sym::mem_discriminant => enforce_mem_discriminant(cx, func, expr.span, args[0].span),
79 sym::mem_variant_count => enforce_mem_variant_count(cx, func, expr.span),
80 _ => {}
81 }
82 }
83}