diff options
Diffstat (limited to 'src/tools/clippy/clippy_lints/src/undocumented_unsafe_blocks.rs')
| -rw-r--r-- | src/tools/clippy/clippy_lints/src/undocumented_unsafe_blocks.rs | 467 |
1 files changed, 368 insertions, 99 deletions
diff --git a/src/tools/clippy/clippy_lints/src/undocumented_unsafe_blocks.rs b/src/tools/clippy/clippy_lints/src/undocumented_unsafe_blocks.rs index d2e675a78..2e1b6d8d4 100644 --- a/src/tools/clippy/clippy_lints/src/undocumented_unsafe_blocks.rs +++ b/src/tools/clippy/clippy_lints/src/undocumented_unsafe_blocks.rs @@ -1,6 +1,10 @@ +use std::ops::ControlFlow; + use clippy_utils::diagnostics::span_lint_and_help; use clippy_utils::source::walk_span_to_context; +use clippy_utils::visitors::{for_each_expr_with_closures, Descend}; use clippy_utils::{get_parent_node, is_lint_allowed}; +use hir::HirId; use rustc_data_structures::sync::Lrc; use rustc_hir as hir; use rustc_hir::{Block, BlockCheckMode, ItemKind, Node, UnsafeSource}; @@ -59,16 +63,45 @@ declare_clippy_lint! { restriction, "creating an unsafe block without explaining why it is safe" } +declare_clippy_lint! { + /// ### What it does + /// Checks for `// SAFETY: ` comments on safe code. + /// + /// ### Why is this bad? + /// Safe code has no safety requirements, so there is no need to + /// describe safety invariants. + /// + /// ### Example + /// ```rust + /// use std::ptr::NonNull; + /// let a = &mut 42; + /// + /// // SAFETY: references are guaranteed to be non-null. + /// let ptr = NonNull::new(a).unwrap(); + /// ``` + /// Use instead: + /// ```rust + /// use std::ptr::NonNull; + /// let a = &mut 42; + /// + /// let ptr = NonNull::new(a).unwrap(); + /// ``` + #[clippy::version = "1.67.0"] + pub UNNECESSARY_SAFETY_COMMENT, + restriction, + "annotating safe code with a safety comment" +} -declare_lint_pass!(UndocumentedUnsafeBlocks => [UNDOCUMENTED_UNSAFE_BLOCKS]); +declare_lint_pass!(UndocumentedUnsafeBlocks => [UNDOCUMENTED_UNSAFE_BLOCKS, UNNECESSARY_SAFETY_COMMENT]); -impl LateLintPass<'_> for UndocumentedUnsafeBlocks { - fn check_block(&mut self, cx: &LateContext<'_>, block: &'_ Block<'_>) { +impl<'tcx> LateLintPass<'tcx> for UndocumentedUnsafeBlocks { + fn check_block(&mut self, cx: &LateContext<'tcx>, block: &'tcx Block<'tcx>) { if block.rules == BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided) && !in_external_macro(cx.tcx.sess, block.span) && !is_lint_allowed(cx, UNDOCUMENTED_UNSAFE_BLOCKS, block.hir_id) && !is_unsafe_from_proc_macro(cx, block.span) - && !block_has_safety_comment(cx, block) + && !block_has_safety_comment(cx, block.span) + && !block_parents_have_safety_comment(cx, block.hir_id) { let source_map = cx.tcx.sess.source_map(); let span = if source_map.is_multiline(block.span) { @@ -86,35 +119,175 @@ impl LateLintPass<'_> for UndocumentedUnsafeBlocks { "consider adding a safety comment on the preceding line", ); } + + if let Some(tail) = block.expr + && !is_lint_allowed(cx, UNNECESSARY_SAFETY_COMMENT, tail.hir_id) + && !in_external_macro(cx.tcx.sess, tail.span) + && let HasSafetyComment::Yes(pos) = stmt_has_safety_comment(cx, tail.span, tail.hir_id) + && let Some(help_span) = expr_has_unnecessary_safety_comment(cx, tail, pos) + { + span_lint_and_help( + cx, + UNNECESSARY_SAFETY_COMMENT, + tail.span, + "expression has unnecessary safety comment", + Some(help_span), + "consider removing the safety comment", + ); + } } - fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) { - if let hir::ItemKind::Impl(imple) = item.kind - && imple.unsafety == hir::Unsafety::Unsafe - && !in_external_macro(cx.tcx.sess, item.span) - && !is_lint_allowed(cx, UNDOCUMENTED_UNSAFE_BLOCKS, item.hir_id()) - && !is_unsafe_from_proc_macro(cx, item.span) - && !item_has_safety_comment(cx, item) + fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &hir::Stmt<'tcx>) { + let ( + hir::StmtKind::Local(&hir::Local { init: Some(expr), .. }) + | hir::StmtKind::Expr(expr) + | hir::StmtKind::Semi(expr) + ) = stmt.kind else { return }; + if !is_lint_allowed(cx, UNNECESSARY_SAFETY_COMMENT, stmt.hir_id) + && !in_external_macro(cx.tcx.sess, stmt.span) + && let HasSafetyComment::Yes(pos) = stmt_has_safety_comment(cx, stmt.span, stmt.hir_id) + && let Some(help_span) = expr_has_unnecessary_safety_comment(cx, expr, pos) { + span_lint_and_help( + cx, + UNNECESSARY_SAFETY_COMMENT, + stmt.span, + "statement has unnecessary safety comment", + Some(help_span), + "consider removing the safety comment", + ); + } + } + + fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) { + if in_external_macro(cx.tcx.sess, item.span) { + return; + } + + let mk_spans = |pos: BytePos| { let source_map = cx.tcx.sess.source_map(); + let span = Span::new(pos, pos, SyntaxContext::root(), None); + let help_span = source_map.span_extend_to_next_char(span, '\n', true); let span = if source_map.is_multiline(item.span) { source_map.span_until_char(item.span, '\n') } else { item.span }; + (span, help_span) + }; - span_lint_and_help( - cx, - UNDOCUMENTED_UNSAFE_BLOCKS, - span, - "unsafe impl missing a safety comment", - None, - "consider adding a safety comment on the preceding line", - ); + let item_has_safety_comment = item_has_safety_comment(cx, item); + match (&item.kind, item_has_safety_comment) { + // lint unsafe impl without safety comment + (hir::ItemKind::Impl(impl_), HasSafetyComment::No) if impl_.unsafety == hir::Unsafety::Unsafe => { + if !is_lint_allowed(cx, UNDOCUMENTED_UNSAFE_BLOCKS, item.hir_id()) + && !is_unsafe_from_proc_macro(cx, item.span) + { + let source_map = cx.tcx.sess.source_map(); + let span = if source_map.is_multiline(item.span) { + source_map.span_until_char(item.span, '\n') + } else { + item.span + }; + + span_lint_and_help( + cx, + UNDOCUMENTED_UNSAFE_BLOCKS, + span, + "unsafe impl missing a safety comment", + None, + "consider adding a safety comment on the preceding line", + ); + } + }, + // lint safe impl with unnecessary safety comment + (hir::ItemKind::Impl(impl_), HasSafetyComment::Yes(pos)) if impl_.unsafety == hir::Unsafety::Normal => { + if !is_lint_allowed(cx, UNNECESSARY_SAFETY_COMMENT, item.hir_id()) { + let (span, help_span) = mk_spans(pos); + + span_lint_and_help( + cx, + UNNECESSARY_SAFETY_COMMENT, + span, + "impl has unnecessary safety comment", + Some(help_span), + "consider removing the safety comment", + ); + } + }, + (hir::ItemKind::Impl(_), _) => {}, + // const and static items only need a safety comment if their body is an unsafe block, lint otherwise + (&hir::ItemKind::Const(.., body) | &hir::ItemKind::Static(.., body), HasSafetyComment::Yes(pos)) => { + if !is_lint_allowed(cx, UNNECESSARY_SAFETY_COMMENT, body.hir_id) { + let body = cx.tcx.hir().body(body); + if !matches!( + body.value.kind, hir::ExprKind::Block(block, _) + if block.rules == BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided) + ) { + let (span, help_span) = mk_spans(pos); + + span_lint_and_help( + cx, + UNNECESSARY_SAFETY_COMMENT, + span, + &format!("{} has unnecessary safety comment", item.kind.descr()), + Some(help_span), + "consider removing the safety comment", + ); + } + } + }, + // Aside from unsafe impls and consts/statics with an unsafe block, items in general + // do not have safety invariants that need to be documented, so lint those. + (_, HasSafetyComment::Yes(pos)) => { + if !is_lint_allowed(cx, UNNECESSARY_SAFETY_COMMENT, item.hir_id()) { + let (span, help_span) = mk_spans(pos); + + span_lint_and_help( + cx, + UNNECESSARY_SAFETY_COMMENT, + span, + &format!("{} has unnecessary safety comment", item.kind.descr()), + Some(help_span), + "consider removing the safety comment", + ); + } + }, + _ => (), } } } +fn expr_has_unnecessary_safety_comment<'tcx>( + cx: &LateContext<'tcx>, + expr: &'tcx hir::Expr<'tcx>, + comment_pos: BytePos, +) -> Option<Span> { + // this should roughly be the reverse of `block_parents_have_safety_comment` + if for_each_expr_with_closures(cx, expr, |expr| match expr.kind { + hir::ExprKind::Block( + Block { + rules: BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided), + .. + }, + _, + ) => ControlFlow::Break(()), + // statements will be handled by check_stmt itself again + hir::ExprKind::Block(..) => ControlFlow::Continue(Descend::No), + _ => ControlFlow::Continue(Descend::Yes), + }) + .is_some() + { + return None; + } + + let source_map = cx.tcx.sess.source_map(); + let span = Span::new(comment_pos, comment_pos, SyntaxContext::root(), None); + let help_span = source_map.span_extend_to_next_char(span, '\n', true); + + Some(help_span) +} + fn is_unsafe_from_proc_macro(cx: &LateContext<'_>, span: Span) -> bool { let source_map = cx.sess().source_map(); let file_pos = source_map.lookup_byte_offset(span.lo()); @@ -126,8 +299,41 @@ fn is_unsafe_from_proc_macro(cx: &LateContext<'_>, span: Span) -> bool { .map_or(true, |src| !src.starts_with("unsafe")) } +// Checks if any parent {expression, statement, block, local, const, static} +// has a safety comment +fn block_parents_have_safety_comment(cx: &LateContext<'_>, id: hir::HirId) -> bool { + if let Some(node) = get_parent_node(cx.tcx, id) { + return match node { + Node::Expr(expr) => !is_branchy(expr) && span_in_body_has_safety_comment(cx, expr.span), + Node::Stmt(hir::Stmt { + kind: + hir::StmtKind::Local(hir::Local { span, .. }) + | hir::StmtKind::Expr(hir::Expr { span, .. }) + | hir::StmtKind::Semi(hir::Expr { span, .. }), + .. + }) + | Node::Local(hir::Local { span, .. }) + | Node::Item(hir::Item { + kind: hir::ItemKind::Const(..) | ItemKind::Static(..), + span, + .. + }) => span_in_body_has_safety_comment(cx, *span), + _ => false, + }; + } + false +} + +/// Checks if an expression is "branchy", e.g. loop, match/if/etc. +fn is_branchy(expr: &hir::Expr<'_>) -> bool { + matches!( + expr.kind, + hir::ExprKind::If(..) | hir::ExprKind::Loop(..) | hir::ExprKind::Match(..) + ) +} + /// Checks if the lines immediately preceding the block contain a safety comment. -fn block_has_safety_comment(cx: &LateContext<'_>, block: &hir::Block<'_>) -> bool { +fn block_has_safety_comment(cx: &LateContext<'_>, span: Span) -> bool { // This intentionally ignores text before the start of a function so something like: // ``` // // SAFETY: reason @@ -136,85 +342,134 @@ fn block_has_safety_comment(cx: &LateContext<'_>, block: &hir::Block<'_>) -> boo // won't work. This is to avoid dealing with where such a comment should be place relative to // attributes and doc comments. - span_from_macro_expansion_has_safety_comment(cx, block.span) || span_in_body_has_safety_comment(cx, block.span) + matches!( + span_from_macro_expansion_has_safety_comment(cx, span), + HasSafetyComment::Yes(_) + ) || span_in_body_has_safety_comment(cx, span) +} + +enum HasSafetyComment { + Yes(BytePos), + No, + Maybe, } /// Checks if the lines immediately preceding the item contain a safety comment. #[allow(clippy::collapsible_match)] -fn item_has_safety_comment(cx: &LateContext<'_>, item: &hir::Item<'_>) -> bool { - if span_from_macro_expansion_has_safety_comment(cx, item.span) { - return true; +fn item_has_safety_comment(cx: &LateContext<'_>, item: &hir::Item<'_>) -> HasSafetyComment { + match span_from_macro_expansion_has_safety_comment(cx, item.span) { + HasSafetyComment::Maybe => (), + has_safety_comment => return has_safety_comment, } - if item.span.ctxt() == SyntaxContext::root() { - if let Some(parent_node) = get_parent_node(cx.tcx, item.hir_id()) { - let comment_start = match parent_node { - Node::Crate(parent_mod) => { - comment_start_before_impl_in_mod(cx, parent_mod, parent_mod.spans.inner_span, item) - }, - Node::Item(parent_item) => { - if let ItemKind::Mod(parent_mod) = &parent_item.kind { - comment_start_before_impl_in_mod(cx, parent_mod, parent_item.span, item) - } else { - // Doesn't support impls in this position. Pretend a comment was found. - return true; - } - }, - Node::Stmt(stmt) => { - if let Some(stmt_parent) = get_parent_node(cx.tcx, stmt.hir_id) { - match stmt_parent { - Node::Block(block) => walk_span_to_context(block.span, SyntaxContext::root()).map(Span::lo), - _ => { - // Doesn't support impls in this position. Pretend a comment was found. - return true; - }, - } - } else { - // Problem getting the parent node. Pretend a comment was found. - return true; - } - }, - _ => { + if item.span.ctxt() != SyntaxContext::root() { + return HasSafetyComment::No; + } + if let Some(parent_node) = get_parent_node(cx.tcx, item.hir_id()) { + let comment_start = match parent_node { + Node::Crate(parent_mod) => { + comment_start_before_item_in_mod(cx, parent_mod, parent_mod.spans.inner_span, item) + }, + Node::Item(parent_item) => { + if let ItemKind::Mod(parent_mod) = &parent_item.kind { + comment_start_before_item_in_mod(cx, parent_mod, parent_item.span, item) + } else { // Doesn't support impls in this position. Pretend a comment was found. - return true; - }, - }; + return HasSafetyComment::Maybe; + } + }, + Node::Stmt(stmt) => { + if let Some(Node::Block(block)) = get_parent_node(cx.tcx, stmt.hir_id) { + walk_span_to_context(block.span, SyntaxContext::root()).map(Span::lo) + } else { + // Problem getting the parent node. Pretend a comment was found. + return HasSafetyComment::Maybe; + } + }, + _ => { + // Doesn't support impls in this position. Pretend a comment was found. + return HasSafetyComment::Maybe; + }, + }; - let source_map = cx.sess().source_map(); - if let Some(comment_start) = comment_start - && let Ok(unsafe_line) = source_map.lookup_line(item.span.lo()) - && let Ok(comment_start_line) = source_map.lookup_line(comment_start) - && Lrc::ptr_eq(&unsafe_line.sf, &comment_start_line.sf) - && let Some(src) = unsafe_line.sf.src.as_deref() - { - unsafe_line.sf.lines(|lines| { - comment_start_line.line < unsafe_line.line && text_has_safety_comment( + let source_map = cx.sess().source_map(); + if let Some(comment_start) = comment_start + && let Ok(unsafe_line) = source_map.lookup_line(item.span.lo()) + && let Ok(comment_start_line) = source_map.lookup_line(comment_start) + && Lrc::ptr_eq(&unsafe_line.sf, &comment_start_line.sf) + && let Some(src) = unsafe_line.sf.src.as_deref() + { + return unsafe_line.sf.lines(|lines| { + if comment_start_line.line >= unsafe_line.line { + HasSafetyComment::No + } else { + match text_has_safety_comment( src, &lines[comment_start_line.line + 1..=unsafe_line.line], unsafe_line.sf.start_pos.to_usize(), - ) - }) - } else { - // Problem getting source text. Pretend a comment was found. - true - } - } else { - // No parent node. Pretend a comment was found. - true + ) { + Some(b) => HasSafetyComment::Yes(b), + None => HasSafetyComment::No, + } + } + }); + } + } + HasSafetyComment::Maybe +} + +/// Checks if the lines immediately preceding the item contain a safety comment. +#[allow(clippy::collapsible_match)] +fn stmt_has_safety_comment(cx: &LateContext<'_>, span: Span, hir_id: HirId) -> HasSafetyComment { + match span_from_macro_expansion_has_safety_comment(cx, span) { + HasSafetyComment::Maybe => (), + has_safety_comment => return has_safety_comment, + } + + if span.ctxt() != SyntaxContext::root() { + return HasSafetyComment::No; + } + + if let Some(parent_node) = get_parent_node(cx.tcx, hir_id) { + let comment_start = match parent_node { + Node::Block(block) => walk_span_to_context(block.span, SyntaxContext::root()).map(Span::lo), + _ => return HasSafetyComment::Maybe, + }; + + let source_map = cx.sess().source_map(); + if let Some(comment_start) = comment_start + && let Ok(unsafe_line) = source_map.lookup_line(span.lo()) + && let Ok(comment_start_line) = source_map.lookup_line(comment_start) + && Lrc::ptr_eq(&unsafe_line.sf, &comment_start_line.sf) + && let Some(src) = unsafe_line.sf.src.as_deref() + { + return unsafe_line.sf.lines(|lines| { + if comment_start_line.line >= unsafe_line.line { + HasSafetyComment::No + } else { + match text_has_safety_comment( + src, + &lines[comment_start_line.line + 1..=unsafe_line.line], + unsafe_line.sf.start_pos.to_usize(), + ) { + Some(b) => HasSafetyComment::Yes(b), + None => HasSafetyComment::No, + } + } + }); } - } else { - false } + HasSafetyComment::Maybe } -fn comment_start_before_impl_in_mod( +fn comment_start_before_item_in_mod( cx: &LateContext<'_>, parent_mod: &hir::Mod<'_>, parent_mod_span: Span, - imple: &hir::Item<'_>, + item: &hir::Item<'_>, ) -> Option<BytePos> { parent_mod.item_ids.iter().enumerate().find_map(|(idx, item_id)| { - if *item_id == imple.item_id() { + if *item_id == item.item_id() { if idx == 0 { // mod A { /* comment */ unsafe impl T {} ... } // ^------------------------------------------^ returns the start of this span @@ -236,11 +491,11 @@ fn comment_start_before_impl_in_mod( }) } -fn span_from_macro_expansion_has_safety_comment(cx: &LateContext<'_>, span: Span) -> bool { +fn span_from_macro_expansion_has_safety_comment(cx: &LateContext<'_>, span: Span) -> HasSafetyComment { let source_map = cx.sess().source_map(); let ctxt = span.ctxt(); if ctxt == SyntaxContext::root() { - false + HasSafetyComment::Maybe } else { // From a macro expansion. Get the text from the start of the macro declaration to start of the // unsafe block. @@ -252,15 +507,22 @@ fn span_from_macro_expansion_has_safety_comment(cx: &LateContext<'_>, span: Span && let Some(src) = unsafe_line.sf.src.as_deref() { unsafe_line.sf.lines(|lines| { - macro_line.line < unsafe_line.line && text_has_safety_comment( - src, - &lines[macro_line.line + 1..=unsafe_line.line], - unsafe_line.sf.start_pos.to_usize(), - ) + if macro_line.line < unsafe_line.line { + match text_has_safety_comment( + src, + &lines[macro_line.line + 1..=unsafe_line.line], + unsafe_line.sf.start_pos.to_usize(), + ) { + Some(b) => HasSafetyComment::Yes(b), + None => HasSafetyComment::No, + } + } else { + HasSafetyComment::No + } }) } else { // Problem getting source text. Pretend a comment was found. - true + HasSafetyComment::Maybe } } } @@ -299,7 +561,7 @@ fn span_in_body_has_safety_comment(cx: &LateContext<'_>, span: Span) -> bool { src, &lines[body_line.line + 1..=unsafe_line.line], unsafe_line.sf.start_pos.to_usize(), - ) + ).is_some() }) } else { // Problem getting source text. Pretend a comment was found. @@ -311,30 +573,34 @@ fn span_in_body_has_safety_comment(cx: &LateContext<'_>, span: Span) -> bool { } /// Checks if the given text has a safety comment for the immediately proceeding line. -fn text_has_safety_comment(src: &str, line_starts: &[BytePos], offset: usize) -> bool { +fn text_has_safety_comment(src: &str, line_starts: &[BytePos], offset: usize) -> Option<BytePos> { let mut lines = line_starts .array_windows::<2>() .rev() .map_while(|[start, end]| { let start = start.to_usize() - offset; let end = end.to_usize() - offset; - src.get(start..end).map(|text| (start, text.trim_start())) + let text = src.get(start..end)?; + let trimmed = text.trim_start(); + Some((start + (text.len() - trimmed.len()), trimmed)) }) .filter(|(_, text)| !text.is_empty()); let Some((line_start, line)) = lines.next() else { - return false; + return None; }; // Check for a sequence of line comments. if line.starts_with("//") { - let mut line = line; + let (mut line, mut line_start) = (line, line_start); loop { if line.to_ascii_uppercase().contains("SAFETY:") { - return true; + return Some(BytePos( + u32::try_from(line_start).unwrap() + u32::try_from(offset).unwrap(), + )); } match lines.next() { - Some((_, x)) if x.starts_with("//") => line = x, - _ => return false, + Some((s, x)) if x.starts_with("//") => (line, line_start) = (x, s), + _ => return None, } } } @@ -343,16 +609,19 @@ fn text_has_safety_comment(src: &str, line_starts: &[BytePos], offset: usize) -> let (mut line_start, mut line) = (line_start, line); loop { if line.starts_with("/*") { - let src = src[line_start..line_starts.last().unwrap().to_usize() - offset].trim_start(); + let src = &src[line_start..line_starts.last().unwrap().to_usize() - offset]; let mut tokens = tokenize(src); - return src[..tokens.next().unwrap().len as usize] + return (src[..tokens.next().unwrap().len as usize] .to_ascii_uppercase() .contains("SAFETY:") - && tokens.all(|t| t.kind == TokenKind::Whitespace); + && tokens.all(|t| t.kind == TokenKind::Whitespace)) + .then_some(BytePos( + u32::try_from(line_start).unwrap() + u32::try_from(offset).unwrap(), + )); } match lines.next() { Some(x) => (line_start, line) = x, - None => return false, + None => return None, } } } |