rust/clippy_lints/src/disallowed_macros.rs

use clippy_config::types::DisallowedPath;
use clippy_utils::diagnostics::{span_lint_and_then, span_lint_hir_and_then};
use clippy_utils::macros::macro_backtrace;
use rustc_ast::Attribute;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::Diag;
use rustc_hir::def_id::DefIdMap;
use rustc_hir::{
    Expr, ExprKind, ForeignItem, HirId, ImplItem, Item, ItemKind, OwnerId, Pat, Path, Stmt, TraitItem, Ty,
};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::impl_lint_pass;
use rustc_span::{ExpnId, MacroKind, Span};

declare_clippy_lint! {
    /// ### What it does
    /// Denies the configured macros in clippy.toml
    ///
    /// Note: Even though this lint is warn-by-default, it will only trigger if
    /// macros are defined in the clippy.toml file.
    ///
    /// ### Why is this bad?
    /// Some macros are undesirable in certain contexts, and it's beneficial to
    /// lint for them as needed.
    ///
    /// ### Example
    /// An example clippy.toml configuration:
    /// ```toml
    /// # clippy.toml
    /// disallowed-macros = [
    ///     # Can use a string as the path of the disallowed macro.
    ///     "std::print",
    ///     # Can also use an inline table with a `path` key.
    ///     { path = "std::println" },
    ///     # When using an inline table, can add a `reason` for why the macro
    ///     # is disallowed.
    ///     { path = "serde::Serialize", reason = "no serializing" },
    /// ]
    /// ```
    /// ```no_run
    /// use serde::Serialize;
    ///
    /// // Example code where clippy issues a warning
    /// println!("warns");
    ///
    /// // The diagnostic will contain the message "no serializing"
    /// #[derive(Serialize)]
    /// struct Data {
    ///     name: String,
    ///     value: usize,
    /// }
    /// ```
    #[clippy::version = "1.66.0"]
    pub DISALLOWED_MACROS,
    style,
    "use of a disallowed macro"
}

pub struct DisallowedMacros {
    conf_disallowed: Vec<DisallowedPath>,
    disallowed: DefIdMap<usize>,
    seen: FxHashSet<ExpnId>,

    // Track the most recently seen node that can have a `derive` attribute.
    // Needed to use the correct lint level.
    derive_src: Option<OwnerId>,
}

impl DisallowedMacros {
    pub fn new(conf_disallowed: Vec<DisallowedPath>) -> Self {
        Self {
            conf_disallowed,
            disallowed: DefIdMap::default(),
            seen: FxHashSet::default(),
            derive_src: None,
        }
    }

    fn check(&mut self, cx: &LateContext<'_>, span: Span, derive_src: Option<OwnerId>) {
        if self.conf_disallowed.is_empty() {
            return;
        }

        for mac in macro_backtrace(span) {
            if !self.seen.insert(mac.expn) {
                return;
            }

            if let Some(&index) = self.disallowed.get(&mac.def_id) {
                let conf = &self.conf_disallowed[index];
                let msg = format!("use of a disallowed macro `{}`", conf.path());
                let add_note = |diag: &mut Diag<'_, _>| {
                    if let Some(reason) = conf.reason() {
                        diag.note(reason);
                    }
                };
                if matches!(mac.kind, MacroKind::Derive)
                    && let Some(derive_src) = derive_src
                {
                    span_lint_hir_and_then(
                        cx,
                        DISALLOWED_MACROS,
                        cx.tcx.local_def_id_to_hir_id(derive_src.def_id),
                        mac.span,
                        msg,
                        add_note,
                    );
                } else {
                    span_lint_and_then(cx, DISALLOWED_MACROS, mac.span, msg, add_note);
                }
            }
        }
    }
}

impl_lint_pass!(DisallowedMacros => [DISALLOWED_MACROS]);

impl LateLintPass<'_> for DisallowedMacros {
    fn check_crate(&mut self, cx: &LateContext<'_>) {
        for (index, conf) in self.conf_disallowed.iter().enumerate() {
            let segs: Vec<_> = conf.path().split("::").collect();
            for id in clippy_utils::def_path_def_ids(cx, &segs) {
                self.disallowed.insert(id, index);
            }
        }
    }

    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
        self.check(cx, expr.span, None);
        // `$t + $t` can have the context of $t, check also the span of the binary operator
        if let ExprKind::Binary(op, ..) = expr.kind {
            self.check(cx, op.span, None);
        }
    }

    fn check_stmt(&mut self, cx: &LateContext<'_>, stmt: &Stmt<'_>) {
        self.check(cx, stmt.span, None);
    }

    fn check_ty(&mut self, cx: &LateContext<'_>, ty: &Ty<'_>) {
        self.check(cx, ty.span, None);
    }

    fn check_pat(&mut self, cx: &LateContext<'_>, pat: &Pat<'_>) {
        self.check(cx, pat.span, None);
    }

    fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
        self.check(cx, item.span, self.derive_src);
        self.check(cx, item.vis_span, None);

        if matches!(
            item.kind,
            ItemKind::Struct(..) | ItemKind::Enum(..) | ItemKind::Union(..)
        ) && macro_backtrace(item.span).all(|m| !matches!(m.kind, MacroKind::Derive))
        {
            self.derive_src = Some(item.owner_id);
        }
    }

    fn check_foreign_item(&mut self, cx: &LateContext<'_>, item: &ForeignItem<'_>) {
        self.check(cx, item.span, None);
        self.check(cx, item.vis_span, None);
    }

    fn check_impl_item(&mut self, cx: &LateContext<'_>, item: &ImplItem<'_>) {
        self.check(cx, item.span, None);
        self.check(cx, item.vis_span, None);
    }

    fn check_trait_item(&mut self, cx: &LateContext<'_>, item: &TraitItem<'_>) {
        self.check(cx, item.span, None);
    }

    fn check_path(&mut self, cx: &LateContext<'_>, path: &Path<'_>, _: HirId) {
        self.check(cx, path.span, None);
    }

    fn check_attribute(&mut self, cx: &LateContext<'_>, attr: &Attribute) {
        self.check(cx, attr.span, self.derive_src);
    }
}