use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::higher;
use clippy_utils::source::snippet_with_applicability;
-use clippy_utils::sugg::Sugg;
use clippy_utils::ty::is_type_diagnostic_item;
-use clippy_utils::{eq_expr_value, is_lang_ctor, path_to_local, path_to_local_id, peel_blocks, peel_blocks_with_stmt};
+use clippy_utils::{
+ eq_expr_value, get_parent_node, is_else_clause, is_lang_ctor, path_to_local, path_to_local_id, peel_blocks,
+ peel_blocks_with_stmt,
+};
use if_chain::if_chain;
use rustc_errors::Applicability;
-use rustc_hir::LangItem::{OptionNone, OptionSome, ResultOk};
-use rustc_hir::{BindingAnnotation, Expr, ExprKind, PatKind};
+use rustc_hir::LangItem::{OptionNone, OptionSome, ResultErr, ResultOk};
+use rustc_hir::{BindingAnnotation, Expr, ExprKind, Node, PatKind, PathSegment, QPath};
use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::Ty;
use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::sym;
+use rustc_span::{sym, symbol::Symbol};
declare_clippy_lint! {
/// ### What it does
declare_lint_pass!(QuestionMark => [QUESTION_MARK]);
-impl QuestionMark {
- /// Checks if the given expression on the given context matches the following structure:
+enum IfBlockType<'hir> {
+ /// An `if x.is_xxx() { a } else { b } ` expression.
///
- /// ```ignore
- /// if option.is_none() {
- /// return None;
- /// }
- /// ```
- ///
- /// ```ignore
- /// if result.is_err() {
- /// return result;
- /// }
- /// ```
+ /// Contains: caller (x), caller_type, call_sym (is_xxx), if_then (a), if_else (b)
+ IfIs(
+ &'hir Expr<'hir>,
+ Ty<'hir>,
+ Symbol,
+ &'hir Expr<'hir>,
+ Option<&'hir Expr<'hir>>,
+ ),
+ /// An `if let Xxx(a) = b { c } else { d }` expression.
///
- /// If it matches, it will suggest to use the question mark operator instead
- fn check_is_none_or_err_and_early_return(cx: &LateContext<'_>, expr: &Expr<'_>) {
- if_chain! {
- if let Some(higher::If { cond, then, r#else }) = higher::If::hir(expr);
- if let ExprKind::MethodCall(segment, args, _) = &cond.kind;
- if let Some(subject) = args.get(0);
- if (Self::option_check_and_early_return(cx, subject, then) && segment.ident.name == sym!(is_none)) ||
- (Self::result_check_and_early_return(cx, subject, then) && segment.ident.name == sym!(is_err));
- then {
- let mut applicability = Applicability::MachineApplicable;
- let receiver_str = &Sugg::hir_with_applicability(cx, subject, "..", &mut applicability);
- let mut replacement: Option<String> = None;
- if let Some(else_inner) = r#else {
- if eq_expr_value(cx, subject, peel_blocks(else_inner)) {
- replacement = Some(format!("Some({}?)", receiver_str));
- }
- } else if Self::moves_by_default(cx, subject)
- && !matches!(subject.kind, ExprKind::Call(..) | ExprKind::MethodCall(..))
- {
- replacement = Some(format!("{}.as_ref()?;", receiver_str));
- } else {
- replacement = Some(format!("{}?;", receiver_str));
- }
+ /// Contains: let_pat_qpath (Xxx), let_pat_type, let_pat_sym (a), let_expr (b), if_then (c),
+ /// if_else (d)
+ IfLet(
+ &'hir QPath<'hir>,
+ Ty<'hir>,
+ Symbol,
+ &'hir Expr<'hir>,
+ &'hir Expr<'hir>,
+ Option<&'hir Expr<'hir>>,
+ ),
+}
- if let Some(replacement_str) = replacement {
- span_lint_and_sugg(
- cx,
- QUESTION_MARK,
- expr.span,
- "this block may be rewritten with the `?` operator",
- "replace it with",
- replacement_str,
- applicability,
- );
+/// Checks if the given expression on the given context matches the following structure:
+///
+/// ```ignore
+/// if option.is_none() {
+/// return None;
+/// }
+/// ```
+///
+/// ```ignore
+/// if result.is_err() {
+/// return result;
+/// }
+/// ```
+///
+/// If it matches, it will suggest to use the question mark operator instead
+fn check_is_none_or_err_and_early_return<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>) {
+ if_chain! {
+ if let Some(higher::If { cond, then, r#else }) = higher::If::hir(expr);
+ if !is_else_clause(cx.tcx, expr);
+ if let ExprKind::MethodCall(segment, args, _) = &cond.kind;
+ if let Some(caller) = args.get(0);
+ let caller_ty = cx.typeck_results().expr_ty(caller);
+ let if_block = IfBlockType::IfIs(caller, caller_ty, segment.ident.name, then, r#else);
+ if is_early_return(sym::Option, cx, &if_block) || is_early_return(sym::Result, cx, &if_block);
+ then {
+ let mut applicability = Applicability::MachineApplicable;
+ let receiver_str = snippet_with_applicability(cx, caller.span, "..", &mut applicability);
+ let by_ref = !caller_ty.is_copy_modulo_regions(cx.tcx.at(caller.span), cx.param_env) &&
+ !matches!(caller.kind, ExprKind::Call(..) | ExprKind::MethodCall(..));
+ let sugg = if let Some(else_inner) = r#else {
+ if eq_expr_value(cx, caller, peel_blocks(else_inner)) {
+ format!("Some({}?)", receiver_str)
+ } else {
+ return;
}
- }
+ } else {
+ format!("{}{}?;", receiver_str, if by_ref { ".as_ref()" } else { "" })
+ };
+
+ span_lint_and_sugg(
+ cx,
+ QUESTION_MARK,
+ expr.span,
+ "this block may be rewritten with the `?` operator",
+ "replace it with",
+ sugg,
+ applicability,
+ );
}
}
+}
- fn check_if_let_some_or_err_and_early_return(cx: &LateContext<'_>, expr: &Expr<'_>) {
- if_chain! {
- if let Some(higher::IfLet { let_pat, let_expr, if_then, if_else: Some(if_else) })
- = higher::IfLet::hir(cx, expr);
- if let PatKind::TupleStruct(ref path1, fields, None) = let_pat.kind;
- if (Self::option_check_and_early_return(cx, let_expr, if_else) && is_lang_ctor(cx, path1, OptionSome)) ||
- (Self::result_check_and_early_return(cx, let_expr, if_else) && is_lang_ctor(cx, path1, ResultOk));
-
- if let PatKind::Binding(annot, bind_id, _, _) = fields[0].kind;
+fn check_if_let_some_or_err_and_early_return<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>) {
+ if_chain! {
+ if let Some(higher::IfLet { let_pat, let_expr, if_then, if_else }) = higher::IfLet::hir(cx, expr);
+ if !is_else_clause(cx.tcx, expr);
+ if let PatKind::TupleStruct(ref path1, fields, None) = let_pat.kind;
+ if let PatKind::Binding(annot, bind_id, ident, _) = fields[0].kind;
+ let caller_ty = cx.typeck_results().expr_ty(let_expr);
+ let if_block = IfBlockType::IfLet(path1, caller_ty, ident.name, let_expr, if_then, if_else);
+ if (is_early_return(sym::Option, cx, &if_block) && path_to_local_id(peel_blocks(if_then), bind_id))
+ || is_early_return(sym::Result, cx, &if_block);
+ if if_else.map(|e| eq_expr_value(cx, let_expr, peel_blocks(e))).filter(|e| *e).is_none();
+ then {
+ let mut applicability = Applicability::MachineApplicable;
+ let receiver_str = snippet_with_applicability(cx, let_expr.span, "..", &mut applicability);
let by_ref = matches!(annot, BindingAnnotation::Ref | BindingAnnotation::RefMut);
- if path_to_local_id(peel_blocks(if_then), bind_id);
- then {
- let mut applicability = Applicability::MachineApplicable;
- let receiver_str = snippet_with_applicability(cx, let_expr.span, "..", &mut applicability);
- let replacement = format!("{}{}?", receiver_str, if by_ref { ".as_ref()" } else { "" },);
-
- span_lint_and_sugg(
- cx,
- QUESTION_MARK,
- expr.span,
- "this if-let-else may be rewritten with the `?` operator",
- "replace it with",
- replacement,
- applicability,
- );
- }
+ let requires_semi = matches!(get_parent_node(cx.tcx, expr.hir_id), Some(Node::Stmt(_)));
+ let sugg = format!(
+ "{}{}?{}",
+ receiver_str,
+ if by_ref { ".as_ref()" } else { "" },
+ if requires_semi { ";" } else { "" }
+ );
+ span_lint_and_sugg(
+ cx,
+ QUESTION_MARK,
+ expr.span,
+ "this block may be rewritten with the `?` operator",
+ "replace it with",
+ sugg,
+ applicability,
+ );
}
}
+}
- fn result_check_and_early_return(cx: &LateContext<'_>, expr: &Expr<'_>, nested_expr: &Expr<'_>) -> bool {
- Self::is_result(cx, expr) && Self::expression_returns_unmodified_err(cx, nested_expr, expr)
- }
-
- fn option_check_and_early_return(cx: &LateContext<'_>, expr: &Expr<'_>, nested_expr: &Expr<'_>) -> bool {
- Self::is_option(cx, expr) && Self::expression_returns_none(cx, nested_expr)
- }
-
- fn moves_by_default(cx: &LateContext<'_>, expression: &Expr<'_>) -> bool {
- let expr_ty = cx.typeck_results().expr_ty(expression);
-
- !expr_ty.is_copy_modulo_regions(cx.tcx.at(expression.span), cx.param_env)
- }
-
- fn is_option(cx: &LateContext<'_>, expression: &Expr<'_>) -> bool {
- let expr_ty = cx.typeck_results().expr_ty(expression);
-
- is_type_diagnostic_item(cx, expr_ty, sym::Option)
- }
-
- fn is_result(cx: &LateContext<'_>, expression: &Expr<'_>) -> bool {
- let expr_ty = cx.typeck_results().expr_ty(expression);
-
- is_type_diagnostic_item(cx, expr_ty, sym::Result)
- }
-
- fn expression_returns_none(cx: &LateContext<'_>, expression: &Expr<'_>) -> bool {
- match peel_blocks_with_stmt(expression).kind {
- ExprKind::Ret(Some(expr)) => Self::expression_returns_none(cx, expr),
- ExprKind::Path(ref qpath) => is_lang_ctor(cx, qpath, OptionNone),
- _ => false,
- }
+fn is_early_return(smbl: Symbol, cx: &LateContext<'_>, if_block: &IfBlockType<'_>) -> bool {
+ match *if_block {
+ IfBlockType::IfIs(caller, caller_ty, call_sym, if_then, _) => {
+ // If the block could be identified as `if x.is_none()/is_err()`,
+ // we then only need to check the if_then return to see if it is none/err.
+ is_type_diagnostic_item(cx, caller_ty, smbl)
+ && expr_return_none_or_err(smbl, cx, if_then, caller, None)
+ && match smbl {
+ sym::Option => call_sym == sym!(is_none),
+ sym::Result => call_sym == sym!(is_err),
+ _ => false,
+ }
+ },
+ IfBlockType::IfLet(qpath, let_expr_ty, let_pat_sym, let_expr, if_then, if_else) => {
+ is_type_diagnostic_item(cx, let_expr_ty, smbl)
+ && match smbl {
+ sym::Option => {
+ // We only need to check `if let Some(x) = option` not `if let None = option`,
+ // because the later one will be suggested as `if option.is_none()` thus causing conflict.
+ is_lang_ctor(cx, qpath, OptionSome)
+ && if_else.is_some()
+ && expr_return_none_or_err(smbl, cx, if_else.unwrap(), let_expr, None)
+ },
+ sym::Result => {
+ (is_lang_ctor(cx, qpath, ResultOk)
+ && if_else.is_some()
+ && expr_return_none_or_err(smbl, cx, if_else.unwrap(), let_expr, Some(let_pat_sym)))
+ || is_lang_ctor(cx, qpath, ResultErr)
+ && expr_return_none_or_err(smbl, cx, if_then, let_expr, Some(let_pat_sym))
+ },
+ _ => false,
+ }
+ },
}
+}
- fn expression_returns_unmodified_err(cx: &LateContext<'_>, expr: &Expr<'_>, cond_expr: &Expr<'_>) -> bool {
- match peel_blocks_with_stmt(expr).kind {
- ExprKind::Ret(Some(ret_expr)) => Self::expression_returns_unmodified_err(cx, ret_expr, cond_expr),
- ExprKind::Path(_) => path_to_local(expr).is_some() && path_to_local(expr) == path_to_local(cond_expr),
+fn expr_return_none_or_err(
+ smbl: Symbol,
+ cx: &LateContext<'_>,
+ expr: &Expr<'_>,
+ cond_expr: &Expr<'_>,
+ err_sym: Option<Symbol>,
+) -> bool {
+ match peel_blocks_with_stmt(expr).kind {
+ ExprKind::Ret(Some(ret_expr)) => expr_return_none_or_err(smbl, cx, ret_expr, cond_expr, err_sym),
+ ExprKind::Path(ref qpath) => match smbl {
+ sym::Option => is_lang_ctor(cx, qpath, OptionNone),
+ sym::Result => path_to_local(expr).is_some() && path_to_local(expr) == path_to_local(cond_expr),
_ => false,
- }
+ },
+ ExprKind::Call(call_expr, args_expr) => {
+ if_chain! {
+ if smbl == sym::Result;
+ if let ExprKind::Path(QPath::Resolved(_, path)) = &call_expr.kind;
+ if let Some(segment) = path.segments.first();
+ if let Some(err_sym) = err_sym;
+ if let Some(arg) = args_expr.first();
+ if let ExprKind::Path(QPath::Resolved(_, arg_path)) = &arg.kind;
+ if let Some(PathSegment { ident, .. }) = arg_path.segments.first();
+ then {
+ return segment.ident.name == sym::Err && err_sym == ident.name;
+ }
+ }
+ false
+ },
+ _ => false,
}
}
impl<'tcx> LateLintPass<'tcx> for QuestionMark {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
- Self::check_is_none_or_err_and_early_return(cx, expr);
- Self::check_if_let_some_or_err_and_early_return(cx, expr);
+ check_is_none_or_err_and_early_return(cx, expr);
+ check_if_let_some_or_err_and_early_return(cx, expr);
}
}
projects / rust.git / blobdiff