Add new lint doc_include_without_cfg

CHANGELOG.md

@@ -5440,6 +5440,7 @@ Released 2018-09-13
 [`disallowed_type`]: https://rust-lang.github.io/rust-clippy/master/index.html#disallowed_type
 [`disallowed_types`]: https://rust-lang.github.io/rust-clippy/master/index.html#disallowed_types
 [`diverging_sub_expression`]: https://rust-lang.github.io/rust-clippy/master/index.html#diverging_sub_expression
+[`doc_include_without_cfg`]: https://rust-lang.github.io/rust-clippy/master/index.html#doc_include_without_cfg
 [`doc_lazy_continuation`]: https://rust-lang.github.io/rust-clippy/master/index.html#doc_lazy_continuation
 [`doc_link_with_quotes`]: https://rust-lang.github.io/rust-clippy/master/index.html#doc_link_with_quotes
 [`doc_markdown`]: https://rust-lang.github.io/rust-clippy/master/index.html#doc_markdown

README.md

@@ -5,7 +5,7 @@
 
 A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
 
-[There are over 700 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
+[There are over 750 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
 
 Lints are divided into categories, each with a default [lint level](https://doc.rust-lang.org/rustc/lints/levels.html).
 You can choose how much Clippy is supposed to ~~annoy~~ help you by changing the lint level by category.

book/src/README.md

@@ -6,7 +6,7 @@
 A collection of lints to catch common mistakes and improve your
 [Rust](https://github.com/rust-lang/rust) code.
 
-[There are over 700 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
+[There are over 750 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
 
 Lints are divided into categories, each with a default [lint
 level](https://doc.rust-lang.org/rustc/lints/levels.html). You can choose how

clippy_lints/src/declared_lints.rs

@@ -148,6 +148,7 @@ pub static LINTS: &[&crate::LintInfo] = &[
     crate::doc::TEST_ATTR_IN_DOCTEST_INFO,
     crate::doc::TOO_LONG_FIRST_DOC_PARAGRAPH_INFO,
     crate::doc::UNNECESSARY_SAFETY_DOC_INFO,
+    crate::doc::DOC_INCLUDE_WITHOUT_CFG_INFO,
     crate::double_parens::DOUBLE_PARENS_INFO,
     crate::drop_forget_ref::DROP_NON_DROP_INFO,
     crate::drop_forget_ref::FORGET_NON_DROP_INFO,

clippy_lints/src/doc/include_in_doc_without_cfg.rs

@@ -0,0 +1,39 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::source::snippet_opt;
+use rustc_ast::{AttrArgs, AttrArgsEq, AttrKind, AttrStyle, Attribute};
+use rustc_errors::Applicability;
+use rustc_lint::LateContext;
+use rustc_span::sym;
+
+use super::DOC_INCLUDE_WITHOUT_CFG;
+
+pub fn check(cx: &LateContext<'_>, attrs: &[Attribute]) {
+    for attr in attrs {
+        if let AttrKind::Normal(ref normal) = attr.kind
+            && normal.item.path == sym::doc
+            && let AttrArgs::Eq(_, AttrArgsEq::Hir(ref meta)) = normal.item.args
+            && !attr.span.contains(meta.span)
+            // Since the `include_str` is already expanded at this point, we can only take the
+            // whole attribute snippet and then modify for our suggestion.
+            && let Some(snippet) = snippet_opt(cx, attr.span)
+            // We cannot remove this because a `#[doc = include_str!("...")]` attribute can occupy
+            // several lines.
+            && let Some(start) = snippet.find('[')
+            && let Some(end) = snippet.rfind(']')
+        {
+            let snippet = &snippet[start + 1..end];
+            span_lint_and_sugg(
+                cx,
+                DOC_INCLUDE_WITHOUT_CFG,
+                attr.span,
+                "included a file in documentation unconditionally",
+                "use `cfg_attr(doc, doc = \"...\")`",
+                format!(
+                    "#{}[cfg_attr(doc, {snippet})]",
+                    if attr.style == AttrStyle::Inner { "!" } else { "" }
+                ),
+                Applicability::MachineApplicable,
+            );
+        }
+    }
+}

clippy_lints/src/doc/mod.rs

@@ -33,6 +33,7 @@ use std::ops::Range;
 use url::Url;
 
 mod empty_line_after;
+mod include_in_doc_without_cfg;
 mod link_with_quotes;
 mod markdown;
 mod missing_headers;
@@ -532,6 +533,29 @@ declare_clippy_lint! {
     "empty line after doc comments"
 }
 
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks if included files in doc comments are included only for `cfg(doc)`.
+    ///
+    /// ### Why is this bad?
+    /// These files are not useful for compilation but will still be included.
+    /// Also, if any of these non-source code file is updated, it will trigger a
+    /// recompilation.
+    ///
+    /// ### Example
+    /// ```ignore
+    /// #![doc = include_str!("some_file.md")]
+    /// ```
+    /// Use instead:
+    /// ```no_run
+    /// #![cfg_attr(doc, doc = include_str!("some_file.md"))]
+    /// ```
+    #[clippy::version = "1.84.0"]
+    pub DOC_INCLUDE_WITHOUT_CFG,
+    suspicious,
+    "check if files included in documentation are behind `cfg(doc)`"
+}
+
 pub struct Documentation {
     valid_idents: FxHashSet<String>,
     check_private_items: bool,
@@ -690,6 +714,7 @@ fn check_attrs(cx: &LateContext<'_>, valid_idents: &FxHashSet<String>, attrs: &[
         Some(("fake".into(), "fake".into()))
     }
 
+    include_in_doc_without_cfg::check(cx, attrs);
     if suspicious_doc_comments::check(cx, attrs) || empty_line_after::check(cx, attrs) || is_doc_hidden(attrs) {
         return None;
     }