diff --git a/CHANGELOG.md b/CHANGELOG.md index 60c03b03d9be..ca70da5bb517 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -5913,6 +5913,7 @@ Released 2018-09-13 [`to_string_in_format_args`]: https://rust-lang.github.io/rust-clippy/master/index.html#to_string_in_format_args [`to_string_trait_impl`]: https://rust-lang.github.io/rust-clippy/master/index.html#to_string_trait_impl [`todo`]: https://rust-lang.github.io/rust-clippy/master/index.html#todo +[`too_long_first_doc_paragraph`]: https://rust-lang.github.io/rust-clippy/master/index.html#too_long_first_doc_paragraph [`too_many_arguments`]: https://rust-lang.github.io/rust-clippy/master/index.html#too_many_arguments [`too_many_lines`]: https://rust-lang.github.io/rust-clippy/master/index.html#too_many_lines [`toplevel_ref_arg`]: https://rust-lang.github.io/rust-clippy/master/index.html#toplevel_ref_arg diff --git a/clippy_lints/src/declared_lints.rs b/clippy_lints/src/declared_lints.rs index 69f9eb6842bc..2933a65a71f5 100644 --- a/clippy_lints/src/declared_lints.rs +++ b/clippy_lints/src/declared_lints.rs @@ -148,6 +148,7 @@ pub(crate) static LINTS: &[&crate::LintInfo] = &[ crate::doc::NEEDLESS_DOCTEST_MAIN_INFO, crate::doc::SUSPICIOUS_DOC_COMMENTS_INFO, crate::doc::TEST_ATTR_IN_DOCTEST_INFO, + crate::doc::TOO_LONG_FIRST_DOC_PARAGRAPH_INFO, crate::doc::UNNECESSARY_SAFETY_DOC_INFO, crate::double_parens::DOUBLE_PARENS_INFO, crate::drop_forget_ref::DROP_NON_DROP_INFO, diff --git a/clippy_lints/src/doc/mod.rs b/clippy_lints/src/doc/mod.rs index 5b6a5b08aa94..6debcd9b6a0f 100644 --- a/clippy_lints/src/doc/mod.rs +++ b/clippy_lints/src/doc/mod.rs @@ -1,4 +1,6 @@ mod lazy_continuation; +mod too_long_first_doc_paragraph; + use clippy_config::Conf; use clippy_utils::attrs::is_doc_hidden; use clippy_utils::diagnostics::{span_lint, span_lint_and_help}; @@ -422,6 +424,38 @@ declare_clippy_lint! { "require every line of a paragraph to be indented and marked" } +declare_clippy_lint! { + /// ### What it does + /// Checks if the first line in the documentation of items listed in module page is too long. + /// + /// ### Why is this bad? + /// Documentation will show the first paragraph of the doscstring in the summary page of a + /// module, so having a nice, short summary in the first paragraph is part of writing good docs. + /// + /// ### Example + /// ```no_run + /// /// A very short summary. + /// /// A much longer explanation that goes into a lot more detail about + /// /// how the thing works, possibly with doclinks and so one, + /// /// and probably spanning a many rows. + /// struct Foo {} + /// ``` + /// Use instead: + /// ```no_run + /// /// A very short summary. + /// /// + /// /// A much longer explanation that goes into a lot more detail about + /// /// how the thing works, possibly with doclinks and so one, + /// /// and probably spanning a many rows. + /// struct Foo {} + /// ``` + #[clippy::version = "1.81.0"] + pub TOO_LONG_FIRST_DOC_PARAGRAPH, + style, + "ensure that the first line of a documentation paragraph isn't too long" +} + +#[derive(Clone)] pub struct Documentation { valid_idents: &'static FxHashSet, check_private_items: bool, @@ -448,6 +482,7 @@ impl_lint_pass!(Documentation => [ SUSPICIOUS_DOC_COMMENTS, EMPTY_DOCS, DOC_LAZY_CONTINUATION, + TOO_LONG_FIRST_DOC_PARAGRAPH, ]); impl<'tcx> LateLintPass<'tcx> for Documentation { @@ -457,39 +492,50 @@ impl<'tcx> LateLintPass<'tcx> for Documentation { }; match cx.tcx.hir_node(cx.last_node_with_lint_attrs) { - Node::Item(item) => match item.kind { - ItemKind::Fn(sig, _, body_id) => { - if !(is_entrypoint_fn(cx, item.owner_id.to_def_id()) || in_external_macro(cx.tcx.sess, item.span)) { - let body = cx.tcx.hir().body(body_id); - - let panic_info = FindPanicUnwrap::find_span(cx, cx.tcx.typeck(item.owner_id), body.value); - missing_headers::check( + Node::Item(item) => { + too_long_first_doc_paragraph::check( + cx, + item, + attrs, + headers.first_paragraph_len, + self.check_private_items, + ); + match item.kind { + ItemKind::Fn(sig, _, body_id) => { + if !(is_entrypoint_fn(cx, item.owner_id.to_def_id()) + || in_external_macro(cx.tcx.sess, item.span)) + { + let body = cx.tcx.hir().body(body_id); + + let panic_info = FindPanicUnwrap::find_span(cx, cx.tcx.typeck(item.owner_id), body.value); + missing_headers::check( + cx, + item.owner_id, + sig, + headers, + Some(body_id), + panic_info, + self.check_private_items, + ); + } + }, + ItemKind::Trait(_, unsafety, ..) => match (headers.safety, unsafety) { + (false, Safety::Unsafe) => span_lint( cx, - item.owner_id, - sig, - headers, - Some(body_id), - panic_info, - self.check_private_items, - ); - } - }, - ItemKind::Trait(_, unsafety, ..) => match (headers.safety, unsafety) { - (false, Safety::Unsafe) => span_lint( - cx, - MISSING_SAFETY_DOC, - cx.tcx.def_span(item.owner_id), - "docs for unsafe trait missing `# Safety` section", - ), - (true, Safety::Safe) => span_lint( - cx, - UNNECESSARY_SAFETY_DOC, - cx.tcx.def_span(item.owner_id), - "docs for safe trait have unnecessary `# Safety` section", - ), + MISSING_SAFETY_DOC, + cx.tcx.def_span(item.owner_id), + "docs for unsafe trait missing `# Safety` section", + ), + (true, Safety::Safe) => span_lint( + cx, + UNNECESSARY_SAFETY_DOC, + cx.tcx.def_span(item.owner_id), + "docs for safe trait have unnecessary `# Safety` section", + ), + _ => (), + }, _ => (), - }, - _ => (), + } }, Node::TraitItem(trait_item) => { if let TraitItemKind::Fn(sig, ..) = trait_item.kind @@ -547,6 +593,7 @@ struct DocHeaders { safety: bool, errors: bool, panics: bool, + first_paragraph_len: usize, } /// Does some pre-processing on raw, desugared `#[doc]` attributes such as parsing them and @@ -653,6 +700,7 @@ fn check_doc<'a, Events: Iterator, Range, Range { if let End(TagEnd::Heading(_)) = event { diff --git a/clippy_lints/src/doc/too_long_first_doc_paragraph.rs b/clippy_lints/src/doc/too_long_first_doc_paragraph.rs new file mode 100644 index 000000000000..7bb3bb12f2ca --- /dev/null +++ b/clippy_lints/src/doc/too_long_first_doc_paragraph.rs @@ -0,0 +1,91 @@ +use rustc_ast::ast::Attribute; +use rustc_errors::Applicability; +use rustc_hir::{Item, ItemKind}; +use rustc_lint::LateContext; + +use clippy_utils::diagnostics::span_lint_and_then; +use clippy_utils::is_from_proc_macro; +use clippy_utils::source::snippet_opt; + +use super::TOO_LONG_FIRST_DOC_PARAGRAPH; + +pub(super) fn check( + cx: &LateContext<'_>, + item: &Item<'_>, + attrs: &[Attribute], + mut first_paragraph_len: usize, + check_private_items: bool, +) { + if !check_private_items && !cx.effective_visibilities.is_exported(item.owner_id.def_id) { + return; + } + if first_paragraph_len <= 200 + || !matches!( + item.kind, + // This is the list of items which can be documented AND are displayed on the module + // page. So associated items or impl blocks are not part of this list. + ItemKind::Static(..) + | ItemKind::Const(..) + | ItemKind::Fn(..) + | ItemKind::Macro(..) + | ItemKind::Mod(..) + | ItemKind::TyAlias(..) + | ItemKind::Enum(..) + | ItemKind::Struct(..) + | ItemKind::Union(..) + | ItemKind::Trait(..) + | ItemKind::TraitAlias(..) + ) + { + return; + } + + let mut spans = Vec::new(); + let mut should_suggest_empty_doc = false; + + for attr in attrs { + if let Some(doc) = attr.doc_str() { + spans.push(attr.span); + let doc = doc.as_str(); + let doc = doc.trim(); + if spans.len() == 1 { + // We make this suggestion only if the first doc line ends with a punctuation + // because it might just need to add an empty line with `///`. + should_suggest_empty_doc = doc.ends_with('.') || doc.ends_with('!') || doc.ends_with('?'); + } + let len = doc.chars().count(); + if len >= first_paragraph_len { + break; + } + first_paragraph_len -= len; + } + } + + let &[first_span, .., last_span] = spans.as_slice() else { + return; + }; + if is_from_proc_macro(cx, item) { + return; + } + + span_lint_and_then( + cx, + TOO_LONG_FIRST_DOC_PARAGRAPH, + first_span.with_hi(last_span.lo()), + "first doc comment paragraph is too long", + |diag| { + if should_suggest_empty_doc + && let Some(second_span) = spans.get(1) + && let new_span = first_span.with_hi(second_span.lo()).with_lo(first_span.hi()) + && let Some(snippet) = snippet_opt(cx, new_span) + { + diag.span_suggestion( + new_span, + "add an empty line", + format!("{snippet}///\n"), + Applicability::MachineApplicable, + ); + } + }, + ); +} diff --git a/clippy_utils/src/lib.rs b/clippy_utils/src/lib.rs index 1d5f1a2a2bb1..7d613a50665f 100644 --- a/clippy_utils/src/lib.rs +++ b/clippy_utils/src/lib.rs @@ -150,6 +150,7 @@ macro_rules! extract_msrv_attr { /// If the given expression is a local binding, find the initializer expression. /// If that initializer expression is another local binding, find its initializer again. +/// /// This process repeats as long as possible (but usually no more than once). Initializer /// expressions with adjustments are ignored. If this is not desired, use [`find_binding_init`] /// instead. @@ -180,6 +181,7 @@ pub fn expr_or_init<'a, 'b, 'tcx: 'b>(cx: &LateContext<'tcx>, mut expr: &'a Expr } /// Finds the initializer expression for a local binding. Returns `None` if the binding is mutable. +/// /// By only considering immutable bindings, we guarantee that the returned expression represents the /// value of the binding wherever it is referenced. /// @@ -428,12 +430,12 @@ pub fn qpath_generic_tys<'tcx>(qpath: &QPath<'tcx>) -> impl Iterator( path_def_id(cx, maybe_path).map_or(false, |id| cx.tcx.is_diagnostic_item(diag_item, id)) } -/// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the +/// THIS METHOD IS DEPRECATED. Matches a `Path` against a slice of segment string literals. +/// +/// This method is deprecated and will eventually be removed since it does not match against the /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from /// `QPath::Resolved.1.res.opt_def_id()`. /// -/// Matches a `Path` against a slice of segment string literals. -/// /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a /// `rustc_hir::Path`. /// @@ -903,6 +905,7 @@ pub fn is_default_equivalent_call(cx: &LateContext<'_>, repl_func: &Expr<'_>) -> } /// Returns true if the expr is equal to `Default::default()` of it's type when evaluated. +/// /// It doesn't cover all cases, for example indirect function calls (some of std /// functions are supported) but it is the best we have. pub fn is_default_equivalent(cx: &LateContext<'_>, e: &Expr<'_>) -> bool { @@ -1059,6 +1062,7 @@ impl std::ops::BitOrAssign for CaptureKind { } /// Given an expression referencing a local, determines how it would be captured in a closure. +/// /// Note as this will walk up to parent expressions until the capture can be determined it should /// only be used while making a closure somewhere a value is consumed. e.g. a block, match arm, or /// function argument (other than a receiver). @@ -2361,8 +2365,9 @@ pub fn fn_def_id_with_node_args<'tcx>( } /// Returns `Option` where String is a textual representation of the type encapsulated in -/// the slice iff the given expression is a slice of primitives (as defined in the -/// `is_recursively_primitive_type` function) and `None` otherwise. +/// the slice iff the given expression is a slice of primitives. +/// +/// (As defined in the `is_recursively_primitive_type` function.) Returns `None` otherwise. pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option { let expr_type = cx.typeck_results().expr_ty_adjusted(expr); let expr_kind = expr_type.kind(); diff --git a/clippy_utils/src/macros.rs b/clippy_utils/src/macros.rs index 455239cc37f3..3c85eb1296e1 100644 --- a/clippy_utils/src/macros.rs +++ b/clippy_utils/src/macros.rs @@ -150,10 +150,11 @@ pub fn first_node_macro_backtrace(cx: &LateContext<'_>, node: &impl HirNode) -> } /// If `node` is the "first node" in a macro expansion, returns `Some` with the `ExpnId` of the -/// macro call site (i.e. the parent of the macro expansion). This generally means that `node` -/// is the outermost node of an entire macro expansion, but there are some caveats noted below. -/// This is useful for finding macro calls while visiting the HIR without processing the macro call -/// at every node within its expansion. +/// macro call site (i.e. the parent of the macro expansion). +/// +/// This generally means that `node` is the outermost node of an entire macro expansion, but there +/// are some caveats noted below. This is useful for finding macro calls while visiting the HIR +/// without processing the macro call at every node within its expansion. /// /// If you already have immediate access to the parent node, it is simpler to /// just check the context of that span directly (e.g. `parent.span.from_expansion()`). diff --git a/clippy_utils/src/source.rs b/clippy_utils/src/source.rs index 496c8f5b5537..924cdf1b8735 100644 --- a/clippy_utils/src/source.rs +++ b/clippy_utils/src/source.rs @@ -527,9 +527,10 @@ pub fn snippet_block_with_context<'a>( (reindent_multiline(snip, true, indent), from_macro) } -/// Same as `snippet_with_applicability`, but first walks the span up to the given context. This -/// will result in the macro call, rather than the expansion, if the span is from a child context. -/// If the span is not from a child context, it will be used directly instead. +/// Same as `snippet_with_applicability`, but first walks the span up to the given context. +/// +/// This will result in the macro call, rather than the expansion, if the span is from a child +/// context. If the span is not from a child context, it will be used directly instead. /// /// e.g. Given the expression `&vec![]`, getting a snippet from the span for `vec![]` as a HIR node /// would result in `box []`. If given the context of the address of expression, this function will @@ -572,9 +573,10 @@ fn snippet_with_context_sess<'a>( } /// Walks the span up to the target context, thereby returning the macro call site if the span is -/// inside a macro expansion, or the original span if it is not. Note this will return `None` in the -/// case of the span being in a macro expansion, but the target context is from expanding a macro -/// argument. +/// inside a macro expansion, or the original span if it is not. +/// +/// Note this will return `None` in the case of the span being in a macro expansion, but the target +/// context is from expanding a macro argument. /// /// Given the following /// diff --git a/clippy_utils/src/ty.rs b/clippy_utils/src/ty.rs index 812fb647fdab..de5ae484834c 100644 --- a/clippy_utils/src/ty.rs +++ b/clippy_utils/src/ty.rs @@ -160,8 +160,10 @@ pub fn get_type_diagnostic_name(cx: &LateContext<'_>, ty: Ty<'_>) -> Option, ty: Ty<'_>) -> bool { matches!( get_type_diagnostic_name(cx, ty), @@ -398,8 +400,10 @@ fn is_normalizable_helper<'tcx>( } /// Returns `true` if the given type is a non aggregate primitive (a `bool` or `char`, any -/// integer or floating-point number type). For checking aggregation of primitive types (e.g. -/// tuples and slices of primitive type) see `is_recursively_primitive_type` +/// integer or floating-point number type). +/// +/// For checking aggregation of primitive types (e.g. tuples and slices of primitive type) see +/// `is_recursively_primitive_type` pub fn is_non_aggregate_primitive_type(ty: Ty<'_>) -> bool { matches!(ty.kind(), ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_)) } @@ -476,9 +480,10 @@ pub fn match_type(cx: &LateContext<'_>, ty: Ty<'_>, path: &[&str]) -> bool { } } -/// Checks if the drop order for a type matters. Some std types implement drop solely to -/// deallocate memory. For these types, and composites containing them, changing the drop order -/// won't result in any observable side effects. +/// Checks if the drop order for a type matters. +/// +/// Some std types implement drop solely to deallocate memory. For these types, and composites +/// containing them, changing the drop order won't result in any observable side effects. pub fn needs_ordered_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool { fn needs_ordered_drop_inner<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, seen: &mut FxHashSet>) -> bool { if !seen.insert(ty) { @@ -1324,6 +1329,7 @@ pub fn deref_chain<'cx, 'tcx>(cx: &'cx LateContext<'tcx>, ty: Ty<'tcx>) -> impl } /// Checks if a Ty<'_> has some inherent method Symbol. +/// /// This does not look for impls in the type's `Deref::Target` type. /// If you need this, you should wrap this call in `clippy_utils::ty::deref_chain().any(...)`. pub fn get_adt_inherent_method<'a>(cx: &'a LateContext<'_>, ty: Ty<'_>, method_name: Symbol) -> Option<&'a AssocItem> { diff --git a/tests/ui/too_long_first_doc_paragraph-fix.fixed b/tests/ui/too_long_first_doc_paragraph-fix.fixed new file mode 100644 index 000000000000..d4a0cdf3447f --- /dev/null +++ b/tests/ui/too_long_first_doc_paragraph-fix.fixed @@ -0,0 +1,9 @@ +#![warn(clippy::too_long_first_doc_paragraph)] + +/// A very short summary. +/// +/// A much longer explanation that goes into a lot more detail about +/// how the thing works, possibly with doclinks and so one, +/// and probably spanning a many rows. Blablabla, it needs to be over +/// 200 characters so I needed to write something longeeeeeeer. +pub struct Foo; diff --git a/tests/ui/too_long_first_doc_paragraph-fix.rs b/tests/ui/too_long_first_doc_paragraph-fix.rs new file mode 100644 index 000000000000..5a3b6c42a328 --- /dev/null +++ b/tests/ui/too_long_first_doc_paragraph-fix.rs @@ -0,0 +1,8 @@ +#![warn(clippy::too_long_first_doc_paragraph)] + +/// A very short summary. +/// A much longer explanation that goes into a lot more detail about +/// how the thing works, possibly with doclinks and so one, +/// and probably spanning a many rows. Blablabla, it needs to be over +/// 200 characters so I needed to write something longeeeeeeer. +pub struct Foo; diff --git a/tests/ui/too_long_first_doc_paragraph-fix.stderr b/tests/ui/too_long_first_doc_paragraph-fix.stderr new file mode 100644 index 000000000000..6403265a39c5 --- /dev/null +++ b/tests/ui/too_long_first_doc_paragraph-fix.stderr @@ -0,0 +1,20 @@ +error: first doc comment paragraph is too long + --> tests/ui/too_long_first_doc_paragraph-fix.rs:3:1 + | +LL | / /// A very short summary. +LL | | /// A much longer explanation that goes into a lot more detail about +LL | | /// how the thing works, possibly with doclinks and so one, +LL | | /// and probably spanning a many rows. Blablabla, it needs to be over +LL | | /// 200 characters so I needed to write something longeeeeeeer. + | |_ + | + = note: `-D clippy::too-long-first-doc-paragraph` implied by `-D warnings` + = help: to override `-D warnings` add `#[allow(clippy::too_long_first_doc_paragraph)]` +help: add an empty line + | +LL ~ /// A very short summary. +LL + /// + | + +error: aborting due to 1 previous error + diff --git a/tests/ui/too_long_first_doc_paragraph.rs b/tests/ui/too_long_first_doc_paragraph.rs new file mode 100644 index 000000000000..1042249c5b7b --- /dev/null +++ b/tests/ui/too_long_first_doc_paragraph.rs @@ -0,0 +1,53 @@ +//@no-rustfix + +#![warn(clippy::too_long_first_doc_paragraph)] + +/// Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nunc turpis nunc, lacinia +/// a dolor in, pellentesque aliquet enim. Cras nec maximus sem. Mauris arcu libero, +/// gravida non lacinia at, rhoncus eu lacus. +pub struct Bar; + +// Should not warn! (not an item visible on mod page) +/// Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nunc turpis nunc, lacinia +/// a dolor in, pellentesque aliquet enim. Cras nec maximus sem. Mauris arcu libero, +/// gravida non lacinia at, rhoncus eu lacus. +impl Bar {} + +// Should not warn! (less than 80 characters) +/// Lorem ipsum dolor sit amet, consectetur adipiscing elit. +/// +/// Nunc turpis nunc, lacinia +/// a dolor in, pellentesque aliquet enim. Cras nec maximus sem. Mauris arcu libero, +/// gravida non lacinia at, rhoncus eu lacus. +pub enum Enum { + A, +} + +/// Lorem +/// ipsum dolor sit amet, consectetur adipiscing elit. Nunc turpis nunc, lacinia +/// a dolor in, pellentesque aliquet enim. Cras nec maximus sem. Mauris arcu libero, +/// gravida non lacinia at, rhoncus eu lacus. +pub union Union { + a: u8, + b: u8, +} + +// Should not warn! (title) +/// # bla +/// Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nunc turpis nunc, lacinia +/// a dolor in, pellentesque aliquet enim. Cras nec maximus sem. Mauris arcu libero, +/// gravida non lacinia at, rhoncus eu lacus. +pub union Union2 { + a: u8, + b: u8, +} + +// Should not warn! (not public) +/// Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nunc turpis nunc, lacinia +/// a dolor in, pellentesque aliquet enim. Cras nec maximus sem. Mauris arcu libero, +/// gravida non lacinia at, rhoncus eu lacus. +fn f() {} + +fn main() { + // test code goes here +} diff --git a/tests/ui/too_long_first_doc_paragraph.stderr b/tests/ui/too_long_first_doc_paragraph.stderr new file mode 100644 index 000000000000..7f48e5cf884e --- /dev/null +++ b/tests/ui/too_long_first_doc_paragraph.stderr @@ -0,0 +1,22 @@ +error: first doc comment paragraph is too long + --> tests/ui/too_long_first_doc_paragraph.rs:5:1 + | +LL | / /// Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nunc turpis nunc, lacinia +LL | | /// a dolor in, pellentesque aliquet enim. Cras nec maximus sem. Mauris arcu libero, +LL | | /// gravida non lacinia at, rhoncus eu lacus. + | |_ + | + = note: `-D clippy::too-long-first-doc-paragraph` implied by `-D warnings` + = help: to override `-D warnings` add `#[allow(clippy::too_long_first_doc_paragraph)]` + +error: first doc comment paragraph is too long + --> tests/ui/too_long_first_doc_paragraph.rs:26:1 + | +LL | / /// Lorem +LL | | /// ipsum dolor sit amet, consectetur adipiscing elit. Nunc turpis nunc, lacinia +LL | | /// a dolor in, pellentesque aliquet enim. Cras nec maximus sem. Mauris arcu libero, +LL | | /// gravida non lacinia at, rhoncus eu lacus. + | |_ + +error: aborting due to 2 previous errors +