Auto merge of #12341 - y21:issue12337, r=dswij
Check for try blocks in `question_mark` more consistently Fixes #12337 I split this PR up into two commits since this moves a method out of an `impl`, which makes for a pretty bad diff (the `&self` parameter is now unused, and there isn't a reason for that function to be part of the `impl` now). The first commit is the actual relevant change and the 2nd commit just moves stuff (github's "hide whitespace" makes the diff easier to look at) ------------ Now for the actual issue: `?` within `try {}` blocks desugars to a `break` to the block, rather than a `return`, so that changes behavior in those cases. The lint has multiple patterns to look for and in *some* of them it already does correctly check whether we're in a try block, but this isn't done for all of its patterns. We could add another `self.inside_try_block()` check to the function that looks for `let-else-return`, but I chose to actually just move those checks out and instead have them in `LintPass::check_{stmt,expr}`. This has the advantage that we can't (easily) accidentally forget to add that check in new patterns that might be added in the future. (There's also a bit of a subtle interaction between two lints, where `question_mark`'s LintPass calls into `manual_let_else`, so I added a check to make sure we don't avoid linting for something that doesn't have anything to do with `?`) changelog: [`question_mark`]: avoid linting on try blocks in more cases
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bors
commit
e970fa52e7
5 changed files with 171 additions and 134 deletions
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@ -203,109 +203,107 @@ fn expr_return_none_or_err(
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}
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}
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/// Checks if the given expression on the given context matches the following structure:
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///
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/// ```ignore
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/// if option.is_none() {
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/// return None;
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/// }
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/// ```
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///
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/// ```ignore
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/// if result.is_err() {
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/// return result;
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/// }
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/// ```
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///
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/// If it matches, it will suggest to use the question mark operator instead
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fn check_is_none_or_err_and_early_return<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>) {
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if let Some(higher::If { cond, then, r#else }) = higher::If::hir(expr)
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&& !is_else_clause(cx.tcx, expr)
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&& let ExprKind::MethodCall(segment, caller, ..) = &cond.kind
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&& let caller_ty = cx.typeck_results().expr_ty(caller)
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&& let if_block = IfBlockType::IfIs(caller, caller_ty, segment.ident.name, then)
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&& (is_early_return(sym::Option, cx, &if_block) || is_early_return(sym::Result, cx, &if_block))
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{
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let mut applicability = Applicability::MachineApplicable;
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let receiver_str = snippet_with_applicability(cx, caller.span, "..", &mut applicability);
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let by_ref = !caller_ty.is_copy_modulo_regions(cx.tcx, cx.param_env)
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&& !matches!(caller.kind, ExprKind::Call(..) | ExprKind::MethodCall(..));
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let sugg = if let Some(else_inner) = r#else {
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if eq_expr_value(cx, caller, peel_blocks(else_inner)) {
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format!("Some({receiver_str}?)")
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} else {
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return;
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}
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} else {
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format!("{receiver_str}{}?;", if by_ref { ".as_ref()" } else { "" })
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};
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span_lint_and_sugg(
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cx,
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QUESTION_MARK,
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expr.span,
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"this block may be rewritten with the `?` operator",
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"replace it with",
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sugg,
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applicability,
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);
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}
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}
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fn check_if_let_some_or_err_and_early_return<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>) {
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if let Some(higher::IfLet {
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let_pat,
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let_expr,
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if_then,
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if_else,
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..
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}) = higher::IfLet::hir(cx, expr)
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&& !is_else_clause(cx.tcx, expr)
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&& let PatKind::TupleStruct(ref path1, [field], ddpos) = let_pat.kind
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&& ddpos.as_opt_usize().is_none()
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&& let PatKind::Binding(BindingAnnotation(by_ref, _), bind_id, ident, None) = field.kind
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&& let caller_ty = cx.typeck_results().expr_ty(let_expr)
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&& let if_block = IfBlockType::IfLet(
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cx.qpath_res(path1, let_pat.hir_id),
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caller_ty,
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ident.name,
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let_expr,
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if_then,
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if_else,
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)
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&& ((is_early_return(sym::Option, cx, &if_block) && path_to_local_id(peel_blocks(if_then), bind_id))
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|| is_early_return(sym::Result, cx, &if_block))
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&& if_else
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.map(|e| eq_expr_value(cx, let_expr, peel_blocks(e)))
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.filter(|e| *e)
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.is_none()
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{
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let mut applicability = Applicability::MachineApplicable;
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let receiver_str = snippet_with_applicability(cx, let_expr.span, "..", &mut applicability);
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let requires_semi = matches!(cx.tcx.parent_hir_node(expr.hir_id), Node::Stmt(_));
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let sugg = format!(
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"{receiver_str}{}?{}",
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if by_ref == ByRef::Yes { ".as_ref()" } else { "" },
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if requires_semi { ";" } else { "" }
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);
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span_lint_and_sugg(
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cx,
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QUESTION_MARK,
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expr.span,
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"this block may be rewritten with the `?` operator",
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"replace it with",
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sugg,
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applicability,
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);
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}
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}
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impl QuestionMark {
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fn inside_try_block(&self) -> bool {
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self.try_block_depth_stack.last() > Some(&0)
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}
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/// Checks if the given expression on the given context matches the following structure:
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///
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/// ```ignore
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/// if option.is_none() {
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/// return None;
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/// }
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/// ```
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///
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/// ```ignore
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/// if result.is_err() {
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/// return result;
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/// }
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/// ```
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///
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/// If it matches, it will suggest to use the question mark operator instead
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fn check_is_none_or_err_and_early_return<'tcx>(&self, cx: &LateContext<'tcx>, expr: &Expr<'tcx>) {
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if !self.inside_try_block()
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&& let Some(higher::If { cond, then, r#else }) = higher::If::hir(expr)
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&& !is_else_clause(cx.tcx, expr)
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&& let ExprKind::MethodCall(segment, caller, ..) = &cond.kind
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&& let caller_ty = cx.typeck_results().expr_ty(caller)
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&& let if_block = IfBlockType::IfIs(caller, caller_ty, segment.ident.name, then)
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&& (is_early_return(sym::Option, cx, &if_block) || is_early_return(sym::Result, cx, &if_block))
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{
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let mut applicability = Applicability::MachineApplicable;
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let receiver_str = snippet_with_applicability(cx, caller.span, "..", &mut applicability);
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let by_ref = !caller_ty.is_copy_modulo_regions(cx.tcx, cx.param_env)
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&& !matches!(caller.kind, ExprKind::Call(..) | ExprKind::MethodCall(..));
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let sugg = if let Some(else_inner) = r#else {
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if eq_expr_value(cx, caller, peel_blocks(else_inner)) {
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format!("Some({receiver_str}?)")
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} else {
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return;
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}
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} else {
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format!("{receiver_str}{}?;", if by_ref { ".as_ref()" } else { "" })
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};
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span_lint_and_sugg(
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cx,
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QUESTION_MARK,
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expr.span,
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"this block may be rewritten with the `?` operator",
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"replace it with",
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sugg,
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applicability,
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);
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}
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}
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fn check_if_let_some_or_err_and_early_return<'tcx>(&self, cx: &LateContext<'tcx>, expr: &Expr<'tcx>) {
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if !self.inside_try_block()
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&& let Some(higher::IfLet {
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let_pat,
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let_expr,
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if_then,
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if_else,
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..
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}) = higher::IfLet::hir(cx, expr)
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&& !is_else_clause(cx.tcx, expr)
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&& let PatKind::TupleStruct(ref path1, [field], ddpos) = let_pat.kind
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&& ddpos.as_opt_usize().is_none()
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&& let PatKind::Binding(BindingAnnotation(by_ref, _), bind_id, ident, None) = field.kind
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&& let caller_ty = cx.typeck_results().expr_ty(let_expr)
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&& let if_block = IfBlockType::IfLet(
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cx.qpath_res(path1, let_pat.hir_id),
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caller_ty,
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ident.name,
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let_expr,
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if_then,
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if_else,
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)
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&& ((is_early_return(sym::Option, cx, &if_block) && path_to_local_id(peel_blocks(if_then), bind_id))
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|| is_early_return(sym::Result, cx, &if_block))
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&& if_else
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.map(|e| eq_expr_value(cx, let_expr, peel_blocks(e)))
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.filter(|e| *e)
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.is_none()
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{
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let mut applicability = Applicability::MachineApplicable;
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let receiver_str = snippet_with_applicability(cx, let_expr.span, "..", &mut applicability);
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let requires_semi = matches!(cx.tcx.parent_hir_node(expr.hir_id), Node::Stmt(_));
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let sugg = format!(
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"{receiver_str}{}?{}",
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if by_ref == ByRef::Yes { ".as_ref()" } else { "" },
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if requires_semi { ";" } else { "" }
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);
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span_lint_and_sugg(
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cx,
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QUESTION_MARK,
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expr.span,
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"this block may be rewritten with the `?` operator",
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"replace it with",
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sugg,
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applicability,
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);
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}
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}
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}
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fn is_try_block(cx: &LateContext<'_>, bl: &rustc_hir::Block<'_>) -> bool {
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@ -324,15 +322,18 @@ impl<'tcx> LateLintPass<'tcx> for QuestionMark {
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return;
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}
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if !in_constant(cx, stmt.hir_id) {
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if !self.inside_try_block() && !in_constant(cx, stmt.hir_id) {
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check_let_some_else_return_none(cx, stmt);
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}
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self.check_manual_let_else(cx, stmt);
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}
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
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if !in_constant(cx, expr.hir_id) && is_lint_allowed(cx, QUESTION_MARK_USED, expr.hir_id) {
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self.check_is_none_or_err_and_early_return(cx, expr);
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self.check_if_let_some_or_err_and_early_return(cx, expr);
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if !self.inside_try_block()
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&& !in_constant(cx, expr.hir_id)
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&& is_lint_allowed(cx, QUESTION_MARK_USED, expr.hir_id)
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{
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check_is_none_or_err_and_early_return(cx, expr);
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check_if_let_some_or_err_and_early_return(cx, expr);
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}
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}
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