rust-clippy/clippy_lints/src/missing_doc.rs

/* This file incorporates work covered by the following copyright and
 * permission notice:
 *   Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
 *   file at the top-level directory of this distribution and at
 *   http://rust-lang.org/COPYRIGHT.
 *
 *   Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
 *   http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
 *   <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 *   option. This file may not be copied, modified, or distributed
 *   except according to those terms.
 */

/* Note: More specifically this lint is largely inspired (aka copied) from *rustc*'s
 * [`missing_doc`].
 *
 * [`missing_doc`]: https://github.com/rust-lang/rust/blob/d6d05904697d89099b55da3331155392f1db9c00/src/librustc_lint/builtin.rs#L246
 */

use rustc::hir;
use rustc::lint::*;
use rustc::ty;
use syntax::ast;
use syntax::attr;
use syntax::codemap::Span;
use utils::in_macro;

/// **What it does:** Warns if there is missing doc for any documentable item (public or private).
///
/// **Why is this bad?** Doc is good. *rustc* has a `MISSING_DOCS` allowed-by-default lint for
/// public members, but has no way to enforce documentation of private items. This lint fixes that.
///
/// **Known problems:** None.
declare_lint! {
    pub MISSING_DOCS_IN_PRIVATE_ITEMS,
    Allow,
    "detects missing documentation for public and private members"
}

pub struct MissingDoc {
    /// Stack of whether #[doc(hidden)] is set
    /// at each level which has lint attributes.
    doc_hidden_stack: Vec<bool>,
}

impl ::std::default::Default for MissingDoc {
    fn default() -> MissingDoc {
        MissingDoc::new()
    }
}

impl MissingDoc {
    pub fn new() -> MissingDoc {
        MissingDoc {
            doc_hidden_stack: vec![false],
        }
    }

    fn doc_hidden(&self) -> bool {
        *self.doc_hidden_stack.last().expect("empty doc_hidden_stack")
    }

    fn check_missing_docs_attrs(&self,
                               cx: &LateContext,
                               attrs: &[ast::Attribute],
                               sp: Span,
                               desc: &'static str) {
        // If we're building a test harness, then warning about
        // documentation is probably not really relevant right now.
        if cx.sess().opts.test {
            return;
        }

        // `#[doc(hidden)]` disables missing_docs check.
        if self.doc_hidden() {
            return;
        }

        if in_macro(cx, sp) {
            return;
        }

        let has_doc = attrs.iter().any(|a| a.is_value_str() && a.name() == "doc");
        if !has_doc {
            cx.span_lint(MISSING_DOCS_IN_PRIVATE_ITEMS, sp,
                         &format!("missing documentation for {}", desc));
        }
    }
}

impl LintPass for MissingDoc {
    fn get_lints(&self) -> LintArray {
        lint_array![MISSING_DOCS_IN_PRIVATE_ITEMS]
    }
}

impl LateLintPass for MissingDoc {
    fn enter_lint_attrs(&mut self, _: &LateContext, attrs: &[ast::Attribute]) {
        let doc_hidden = self.doc_hidden() || attrs.iter().any(|attr| {
            attr.check_name("doc") && match attr.meta_item_list() {
                None => false,
                Some(l) => attr::list_contains_name(&l[..], "hidden"),
            }
        });
        self.doc_hidden_stack.push(doc_hidden);
    }

    fn exit_lint_attrs(&mut self, _: &LateContext, _: &[ast::Attribute]) {
        self.doc_hidden_stack.pop().expect("empty doc_hidden_stack");
    }

    fn check_crate(&mut self, cx: &LateContext, krate: &hir::Crate) {
        self.check_missing_docs_attrs(cx, &krate.attrs, krate.span, "crate");
    }

    fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
        let desc = match it.node {
            hir::ItemConst(..) => "a constant",
            hir::ItemEnum(..) => "an enum",
            hir::ItemFn(..) => "a function",
            hir::ItemMod(..) => "a module",
            hir::ItemStatic(..) => "a static",
            hir::ItemStruct(..) => "a struct",
            hir::ItemTrait(..) => "a trait",
            hir::ItemTy(..) => "a type alias",
            //FIXME:unions: hir::ItemUnion(..) => "a union",
            hir::ItemDefaultImpl(..) |
            hir::ItemExternCrate(..) |
            hir::ItemForeignMod(..) |
            hir::ItemImpl(..) |
            hir::ItemUse(..) => return,
        };

        self.check_missing_docs_attrs(cx, &it.attrs, it.span, desc);
    }

    fn check_trait_item(&mut self, cx: &LateContext, trait_item: &hir::TraitItem) {
        let desc = match trait_item.node {
            hir::ConstTraitItem(..) => "an associated constant",
            hir::MethodTraitItem(..) => "a trait method",
            hir::TypeTraitItem(..) => "an associated type",
        };

        self.check_missing_docs_attrs(cx, &trait_item.attrs, trait_item.span, desc);
    }

    fn check_impl_item(&mut self, cx: &LateContext, impl_item: &hir::ImplItem) {
        // If the method is an impl for a trait, don't doc.
        let def_id = cx.tcx.map.local_def_id(impl_item.id);
        match cx.tcx.impl_or_trait_items.borrow()
                                         .get(&def_id)
                                         .expect("missing method descriptor?!")
                                         .container() {
            ty::TraitContainer(_) => return,
            ty::ImplContainer(cid) => {
                if cx.tcx.impl_trait_ref(cid).is_some() {
                    return
                }
            }
        }

        let desc = match impl_item.node {
            hir::ImplItemKind::Const(..) => "an associated constant",
            hir::ImplItemKind::Method(..) => "a method",
            hir::ImplItemKind::Type(_) => "an associated type",
        };
        self.check_missing_docs_attrs(cx, &impl_item.attrs, impl_item.span, desc);
    }

    fn check_struct_field(&mut self, cx: &LateContext, sf: &hir::StructField) {
        if !sf.is_positional() {
            self.check_missing_docs_attrs(cx, &sf.attrs, sf.span, "a struct field");
        }
    }

    fn check_variant(&mut self, cx: &LateContext, v: &hir::Variant, _: &hir::Generics) {
        self.check_missing_docs_attrs(cx, &v.node.attrs, v.span, "a variant");
    }
}