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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /src/tools/clippy/clippy_lints/src/blocks_in_if_conditions.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/tools/clippy/clippy_lints/src/blocks_in_if_conditions.rs')
-rw-r--r-- | src/tools/clippy/clippy_lints/src/blocks_in_if_conditions.rs | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/src/tools/clippy/clippy_lints/src/blocks_in_if_conditions.rs b/src/tools/clippy/clippy_lints/src/blocks_in_if_conditions.rs new file mode 100644 index 000000000..ad206b5fb --- /dev/null +++ b/src/tools/clippy/clippy_lints/src/blocks_in_if_conditions.rs @@ -0,0 +1,155 @@ +use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg}; +use clippy_utils::get_parent_expr; +use clippy_utils::higher; +use clippy_utils::source::snippet_block_with_applicability; +use clippy_utils::ty::implements_trait; +use if_chain::if_chain; +use rustc_errors::Applicability; +use rustc_hir::intravisit::{walk_expr, Visitor}; +use rustc_hir::{BlockCheckMode, Closure, Expr, ExprKind}; +use rustc_lint::{LateContext, LateLintPass, LintContext}; +use rustc_middle::lint::in_external_macro; +use rustc_session::{declare_lint_pass, declare_tool_lint}; +use rustc_span::sym; + +declare_clippy_lint! { + /// ### What it does + /// Checks for `if` conditions that use blocks containing an + /// expression, statements or conditions that use closures with blocks. + /// + /// ### Why is this bad? + /// Style, using blocks in the condition makes it hard to read. + /// + /// ### Examples + /// ```rust + /// # fn somefunc() -> bool { true }; + /// if { true } { /* ... */ } + /// + /// if { let x = somefunc(); x } { /* ... */ } + /// ``` + /// + /// Use instead: + /// ```rust + /// # fn somefunc() -> bool { true }; + /// if true { /* ... */ } + /// + /// let res = { let x = somefunc(); x }; + /// if res { /* ... */ } + /// ``` + #[clippy::version = "1.45.0"] + pub BLOCKS_IN_IF_CONDITIONS, + style, + "useless or complex blocks that can be eliminated in conditions" +} + +declare_lint_pass!(BlocksInIfConditions => [BLOCKS_IN_IF_CONDITIONS]); + +struct ExVisitor<'a, 'tcx> { + found_block: Option<&'tcx Expr<'tcx>>, + cx: &'a LateContext<'tcx>, +} + +impl<'a, 'tcx> Visitor<'tcx> for ExVisitor<'a, 'tcx> { + fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) { + if let ExprKind::Closure(&Closure { body, .. }) = expr.kind { + // do not lint if the closure is called using an iterator (see #1141) + if_chain! { + if let Some(parent) = get_parent_expr(self.cx, expr); + if let ExprKind::MethodCall(_, [self_arg, ..], _) = &parent.kind; + let caller = self.cx.typeck_results().expr_ty(self_arg); + if let Some(iter_id) = self.cx.tcx.get_diagnostic_item(sym::Iterator); + if implements_trait(self.cx, caller, iter_id, &[]); + then { + return; + } + } + + let body = self.cx.tcx.hir().body(body); + let ex = &body.value; + if let ExprKind::Block(block, _) = ex.kind { + if !body.value.span.from_expansion() && !block.stmts.is_empty() { + self.found_block = Some(ex); + return; + } + } + } + walk_expr(self, expr); + } +} + +const BRACED_EXPR_MESSAGE: &str = "omit braces around single expression condition"; +const COMPLEX_BLOCK_MESSAGE: &str = "in an `if` condition, avoid complex blocks or closures with blocks; \ + instead, move the block or closure higher and bind it with a `let`"; + +impl<'tcx> LateLintPass<'tcx> for BlocksInIfConditions { + fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { + if in_external_macro(cx.sess(), expr.span) { + return; + } + if let Some(higher::If { cond, .. }) = higher::If::hir(expr) { + if let ExprKind::Block(block, _) = &cond.kind { + if block.rules == BlockCheckMode::DefaultBlock { + if block.stmts.is_empty() { + if let Some(ex) = &block.expr { + // don't dig into the expression here, just suggest that they remove + // the block + if expr.span.from_expansion() || ex.span.from_expansion() { + return; + } + let mut applicability = Applicability::MachineApplicable; + span_lint_and_sugg( + cx, + BLOCKS_IN_IF_CONDITIONS, + cond.span, + BRACED_EXPR_MESSAGE, + "try", + format!( + "{}", + snippet_block_with_applicability( + cx, + ex.span, + "..", + Some(expr.span), + &mut applicability + ) + ), + applicability, + ); + } + } else { + let span = block.expr.as_ref().map_or_else(|| block.stmts[0].span, |e| e.span); + if span.from_expansion() || expr.span.from_expansion() { + return; + } + // move block higher + let mut applicability = Applicability::MachineApplicable; + span_lint_and_sugg( + cx, + BLOCKS_IN_IF_CONDITIONS, + expr.span.with_hi(cond.span.hi()), + COMPLEX_BLOCK_MESSAGE, + "try", + format!( + "let res = {}; if res", + snippet_block_with_applicability( + cx, + block.span, + "..", + Some(expr.span), + &mut applicability + ), + ), + applicability, + ); + } + } + } else { + let mut visitor = ExVisitor { found_block: None, cx }; + walk_expr(&mut visitor, cond); + if let Some(block) = visitor.found_block { + span_lint(cx, BLOCKS_IN_IF_CONDITIONS, block.span, COMPLEX_BLOCK_MESSAGE); + } + } + } + } +} |