diff options
| -rw-r--r-- | clippy_lints/src/needless_question_mark.rs | 112 | ||||
| -rw-r--r-- | tests/ui/needless_question_mark.fixed | 5 | ||||
| -rw-r--r-- | tests/ui/needless_question_mark.rs | 5 | ||||
| -rw-r--r-- | tests/ui/needless_question_mark.stderr | 2 |
4 files changed, 30 insertions, 94 deletions
diff --git a/clippy_lints/src/needless_question_mark.rs b/clippy_lints/src/needless_question_mark.rs index 7b156a8c49d..5c9cce6aad4 100644 --- a/clippy_lints/src/needless_question_mark.rs +++ b/clippy_lints/src/needless_question_mark.rs @@ -1,14 +1,13 @@ use clippy_utils::diagnostics::span_lint_and_sugg; +use clippy_utils::is_lang_ctor; use clippy_utils::source::snippet; -use clippy_utils::ty::is_type_diagnostic_item; -use clippy_utils::{differing_macro_contexts, is_lang_ctor}; use if_chain::if_chain; use rustc_errors::Applicability; use rustc_hir::LangItem::{OptionSome, ResultOk}; use rustc_hir::{Body, Expr, ExprKind, LangItem, MatchSource, QPath}; use rustc_lint::{LateContext, LateLintPass}; +use rustc_middle::ty::TyS; use rustc_session::{declare_lint_pass, declare_tool_lint}; -use rustc_span::sym; declare_clippy_lint! { /// **What it does:** @@ -63,12 +62,6 @@ declare_clippy_lint! { declare_lint_pass!(NeedlessQuestionMark => [NEEDLESS_QUESTION_MARK]); -#[derive(Debug)] -enum SomeOkCall<'a> { - SomeCall(&'a Expr<'a>, &'a Expr<'a>), - OkCall(&'a Expr<'a>, &'a Expr<'a>), -} - impl LateLintPass<'_> for NeedlessQuestionMark { /* * The question mark operator is compatible with both Result<T, E> and Option<T>, @@ -90,104 +83,37 @@ impl LateLintPass<'_> for NeedlessQuestionMark { */ fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'_ Expr<'_>) { - let e = match &expr.kind { - ExprKind::Ret(Some(e)) => e, - _ => return, - }; - - if let Some(ok_some_call) = is_some_or_ok_call(cx, e) { - emit_lint(cx, &ok_some_call); + if let ExprKind::Ret(Some(e)) = expr.kind { + check(cx, e); } } fn check_body(&mut self, cx: &LateContext<'_>, body: &'_ Body<'_>) { - // Function / Closure block - let expr_opt = if let ExprKind::Block(block, _) = &body.value.kind { - block.expr - } else { - // Single line closure - Some(&body.value) - }; - - if_chain! { - if let Some(expr) = expr_opt; - if let Some(ok_some_call) = is_some_or_ok_call(cx, expr); - then { - emit_lint(cx, &ok_some_call); - } - }; + check(cx, body.value.peel_blocks()); } } -fn emit_lint(cx: &LateContext<'_>, expr: &SomeOkCall<'_>) { - let (entire_expr, inner_expr) = match expr { - SomeOkCall::OkCall(outer, inner) | SomeOkCall::SomeCall(outer, inner) => (outer, inner), +fn check(cx: &LateContext<'_>, expr: &Expr<'_>) { + let inner_expr = if_chain! { + if let ExprKind::Call(path, [arg]) = &expr.kind; + if let ExprKind::Path(ref qpath) = &path.kind; + if is_lang_ctor(cx, qpath, OptionSome) || is_lang_ctor(cx, qpath, ResultOk); + if let ExprKind::Match(inner_expr_with_q, _, MatchSource::TryDesugar) = &arg.kind; + if let ExprKind::Call(called, [inner_expr]) = &inner_expr_with_q.kind; + if let ExprKind::Path(QPath::LangItem(LangItem::TryIntoResult, _)) = &called.kind; + if expr.span.ctxt() == inner_expr.span.ctxt(); + let expr_ty = cx.typeck_results().expr_ty(expr); + let inner_ty = cx.typeck_results().expr_ty(inner_expr); + if TyS::same_type(expr_ty, inner_ty); + then { inner_expr } else { return; } }; - span_lint_and_sugg( cx, NEEDLESS_QUESTION_MARK, - entire_expr.span, + expr.span, "question mark operator is useless here", "try", format!("{}", snippet(cx, inner_expr.span, r#""...""#)), Applicability::MachineApplicable, ); } - -fn is_some_or_ok_call<'a>(cx: &'a LateContext<'_>, expr: &'a Expr<'_>) -> Option<SomeOkCall<'a>> { - if_chain! { - // Check outer expression matches CALL_IDENT(ARGUMENT) format - if let ExprKind::Call(path, args) = &expr.kind; - if let ExprKind::Path(ref qpath) = &path.kind; - if is_lang_ctor(cx, qpath, OptionSome) || is_lang_ctor(cx, qpath, ResultOk); - - // Extract inner expression from ARGUMENT - if let ExprKind::Match(inner_expr_with_q, _, MatchSource::TryDesugar) = &args[0].kind; - if let ExprKind::Call(called, args) = &inner_expr_with_q.kind; - if args.len() == 1; - - if let ExprKind::Path(QPath::LangItem(LangItem::TryIntoResult, _)) = &called.kind; - then { - // Extract inner expr type from match argument generated by - // question mark operator - let inner_expr = &args[0]; - - // if the inner expr is inside macro but the outer one is not, do not lint (#6921) - if differing_macro_contexts(expr.span, inner_expr.span) { - return None; - } - - let inner_ty = cx.typeck_results().expr_ty(inner_expr); - let outer_ty = cx.typeck_results().expr_ty(expr); - - // Check if outer and inner type are Option - let outer_is_some = is_type_diagnostic_item(cx, outer_ty, sym::option_type); - let inner_is_some = is_type_diagnostic_item(cx, inner_ty, sym::option_type); - - // Check for Option MSRV - if outer_is_some && inner_is_some { - return Some(SomeOkCall::SomeCall(expr, inner_expr)); - } - - // Check if outer and inner type are Result - let outer_is_result = is_type_diagnostic_item(cx, outer_ty, sym::result_type); - let inner_is_result = is_type_diagnostic_item(cx, inner_ty, sym::result_type); - - // Additional check: if the error type of the Result can be converted - // via the From trait, then don't match - let does_not_call_from = !has_implicit_error_from(cx, expr, inner_expr); - - // Must meet Result MSRV - if outer_is_result && inner_is_result && does_not_call_from { - return Some(SomeOkCall::OkCall(expr, inner_expr)); - } - } - } - - None -} - -fn has_implicit_error_from(cx: &LateContext<'_>, entire_expr: &Expr<'_>, inner_result_expr: &Expr<'_>) -> bool { - return cx.typeck_results().expr_ty(entire_expr) != cx.typeck_results().expr_ty(inner_result_expr); -} diff --git a/tests/ui/needless_question_mark.fixed b/tests/ui/needless_question_mark.fixed index 52ddd9d2dc8..f1fc81aa12b 100644 --- a/tests/ui/needless_question_mark.fixed +++ b/tests/ui/needless_question_mark.fixed @@ -94,6 +94,11 @@ where Ok(x?) } +// not quite needless +fn deref_ref(s: Option<&String>) -> Option<&str> { + Some(s?) +} + fn main() {} // #6921 if a macro wraps an expr in Some( ) and the ? is in the macro use, diff --git a/tests/ui/needless_question_mark.rs b/tests/ui/needless_question_mark.rs index 1ea4ba0d83f..44a0c5f61b5 100644 --- a/tests/ui/needless_question_mark.rs +++ b/tests/ui/needless_question_mark.rs @@ -94,6 +94,11 @@ where Ok(x?) } +// not quite needless +fn deref_ref(s: Option<&String>) -> Option<&str> { + Some(s?) +} + fn main() {} // #6921 if a macro wraps an expr in Some( ) and the ? is in the macro use, diff --git a/tests/ui/needless_question_mark.stderr b/tests/ui/needless_question_mark.stderr index afd68d91e51..fa698224530 100644 --- a/tests/ui/needless_question_mark.stderr +++ b/tests/ui/needless_question_mark.stderr @@ -67,7 +67,7 @@ LL | return Ok(t.magic?); | ^^^^^^^^^^^^ help: try: `t.magic` error: question mark operator is useless here - --> $DIR/needless_question_mark.rs:115:27 + --> $DIR/needless_question_mark.rs:120:27 | LL | || -> Option<_> { Some(Some($expr)?) }() | ^^^^^^^^^^^^^^^^^^ help: try: `Some($expr)` |