use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::sugg::Sugg;
use clippy_utils::ty::is_type_diagnostic_item;
-use clippy_utils::usage::contains_return_break_continue_macro;
-use clippy_utils::{eager_or_lazy, in_macro, is_else_clause, is_lang_ctor};
+use clippy_utils::{
+ can_move_expr_to_closure, eager_or_lazy, higher, in_constant, is_else_clause, is_lang_ctor, peel_blocks,
+ peel_hir_expr_while, CaptureKind,
+};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::LangItem::OptionSome;
-use rustc_hir::{Arm, BindingAnnotation, Block, Expr, ExprKind, MatchSource, Mutability, PatKind, UnOp};
+use rustc_hir::{def::Res, BindingAnnotation, Expr, ExprKind, Mutability, PatKind, Path, QPath, UnOp};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::sym;
declare_clippy_lint! {
- /// **What it does:**
+ /// ### What it does
/// Lints usage of `if let Some(v) = ... { y } else { x }` which is more
/// idiomatically done with `Option::map_or` (if the else bit is a pure
/// expression) or `Option::map_or_else` (if the else bit is an impure
/// expression).
///
- /// **Why is this bad?**
- /// Using the dedicated functions of the Option type is clearer and
+ /// ### Why is this bad?
+ /// Using the dedicated functions of the `Option` type is clearer and
/// more concise than an `if let` expression.
///
- /// **Known problems:**
+ /// ### Known problems
/// This lint uses a deliberately conservative metric for checking
/// if the inside of either body contains breaks or continues which will
/// cause it to not suggest a fix if either block contains a loop with
/// continues or breaks contained within the loop.
///
- /// **Example:**
- ///
+ /// ### Example
/// ```rust
/// # let optional: Option<u32> = Some(0);
/// # fn do_complicated_function() -> u32 { 5 };
/// y*y
/// }, |foo| foo);
/// ```
+ #[clippy::version = "1.47.0"]
pub OPTION_IF_LET_ELSE,
- pedantic,
+ nursery,
"reimplementation of Option::map_or"
}
/// Returns true iff the given expression is the result of calling `Result::ok`
fn is_result_ok(cx: &LateContext<'_>, expr: &'_ Expr<'_>) -> bool {
- if let ExprKind::MethodCall(path, _, &[ref receiver], _) = &expr.kind {
+ if let ExprKind::MethodCall(path, &[ref receiver], _) = &expr.kind {
path.ident.name.as_str() == "ok"
- && is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(receiver), sym::result_type)
+ && is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(receiver), sym::Result)
} else {
false
}
none_expr: String,
}
-/// Extracts the body of a given arm. If the arm contains only an expression,
-/// then it returns the expression. Otherwise, it returns the entire block
-fn extract_body_from_arm<'a>(arm: &'a Arm<'a>) -> Option<&'a Expr<'a>> {
- if let ExprKind::Block(
- Block {
- stmts: statements,
- expr: Some(expr),
- ..
- },
- _,
- ) = &arm.body.kind
- {
- if let [] = statements {
- Some(expr)
- } else {
- Some(arm.body)
- }
- } else {
- None
- }
-}
-
fn format_option_in_sugg(cx: &LateContext<'_>, cond_expr: &Expr<'_>, as_ref: bool, as_mut: bool) -> String {
format!(
"{}{}",
- Sugg::hir(cx, cond_expr, "..").maybe_par(),
+ Sugg::hir_with_macro_callsite(cx, cond_expr, "..").maybe_par(),
if as_mut {
".as_mut()"
} else if as_ref {
/// If this expression is the option if let/else construct we're detecting, then
/// this function returns an `OptionIfLetElseOccurence` struct with details if
/// this construct is found, or None if this construct is not found.
-fn detect_option_if_let_else<'tcx>(
- cx: &'_ LateContext<'tcx>,
- expr: &'_ Expr<'tcx>,
-) -> Option<OptionIfLetElseOccurence> {
+fn detect_option_if_let_else<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>) -> Option<OptionIfLetElseOccurence> {
if_chain! {
- if !in_macro(expr.span); // Don't lint macros, because it behaves weirdly
- if let ExprKind::Match(cond_expr, arms, MatchSource::IfLetDesugar{contains_else_clause: true}) = &expr.kind;
+ if !expr.span.from_expansion(); // Don't lint macros, because it behaves weirdly
+ if !in_constant(cx, expr.hir_id);
+ if let Some(higher::IfLet { let_pat, let_expr, if_then, if_else: Some(if_else) })
+ = higher::IfLet::hir(cx, expr);
if !is_else_clause(cx.tcx, expr);
- if arms.len() == 2;
- if !is_result_ok(cx, cond_expr); // Don't lint on Result::ok because a different lint does it already
- if let PatKind::TupleStruct(struct_qpath, [inner_pat], _) = &arms[0].pat.kind;
+ if !is_result_ok(cx, let_expr); // Don't lint on Result::ok because a different lint does it already
+ if let PatKind::TupleStruct(struct_qpath, [inner_pat], _) = &let_pat.kind;
if is_lang_ctor(cx, struct_qpath, OptionSome);
- if let PatKind::Binding(bind_annotation, _, id, _) = &inner_pat.kind;
- if !contains_return_break_continue_macro(arms[0].body);
- if !contains_return_break_continue_macro(arms[1].body);
+ if let PatKind::Binding(bind_annotation, _, id, None) = &inner_pat.kind;
+ if let Some(some_captures) = can_move_expr_to_closure(cx, if_then);
+ if let Some(none_captures) = can_move_expr_to_closure(cx, if_else);
+ if some_captures
+ .iter()
+ .filter_map(|(id, &c)| none_captures.get(id).map(|&c2| (c, c2)))
+ .all(|(x, y)| x.is_imm_ref() && y.is_imm_ref());
then {
let capture_mut = if bind_annotation == &BindingAnnotation::Mutable { "mut " } else { "" };
- let some_body = extract_body_from_arm(&arms[0])?;
- let none_body = extract_body_from_arm(&arms[1])?;
- let method_sugg = if eager_or_lazy::is_eagerness_candidate(cx, none_body) { "map_or" } else { "map_or_else" };
+ let some_body = peel_blocks(if_then);
+ let none_body = peel_blocks(if_else);
+ let method_sugg = if eager_or_lazy::switch_to_eager_eval(cx, none_body) { "map_or" } else { "map_or_else" };
let capture_name = id.name.to_ident_string();
- let (as_ref, as_mut) = match &cond_expr.kind {
+ let (as_ref, as_mut) = match &let_expr.kind {
ExprKind::AddrOf(_, Mutability::Not, _) => (true, false),
ExprKind::AddrOf(_, Mutability::Mut, _) => (false, true),
_ => (bind_annotation == &BindingAnnotation::Ref, bind_annotation == &BindingAnnotation::RefMut),
};
- let cond_expr = match &cond_expr.kind {
+ let cond_expr = match let_expr.kind {
// Pointer dereferencing happens automatically, so we can omit it in the suggestion
ExprKind::Unary(UnOp::Deref, expr) | ExprKind::AddrOf(_, _, expr) => expr,
- _ => cond_expr,
+ _ => let_expr,
};
+ // Check if captures the closure will need conflict with borrows made in the scrutinee.
+ // TODO: check all the references made in the scrutinee expression. This will require interacting
+ // with the borrow checker. Currently only `<local>[.<field>]*` is checked for.
+ if as_ref || as_mut {
+ let e = peel_hir_expr_while(cond_expr, |e| match e.kind {
+ ExprKind::Field(e, _) | ExprKind::AddrOf(_, _, e) => Some(e),
+ _ => None,
+ });
+ if let ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(local_id), .. })) = e.kind {
+ match some_captures.get(local_id)
+ .or_else(|| (method_sugg == "map_or_else").then(|| ()).and_then(|_| none_captures.get(local_id)))
+ {
+ Some(CaptureKind::Value | CaptureKind::Ref(Mutability::Mut)) => return None,
+ Some(CaptureKind::Ref(Mutability::Not)) if as_mut => return None,
+ Some(CaptureKind::Ref(Mutability::Not)) | None => (),
+ }
+ }
+ }
Some(OptionIfLetElseOccurence {
option: format_option_in_sugg(cx, cond_expr, as_ref, as_mut),
method_sugg: method_sugg.to_string(),
- some_expr: format!("|{}{}| {}", capture_mut, capture_name, Sugg::hir(cx, some_body, "..")),
- none_expr: format!("{}{}", if method_sugg == "map_or" { "" } else { "|| " }, Sugg::hir(cx, none_body, "..")),
+ some_expr: format!("|{}{}| {}", capture_mut, capture_name, Sugg::hir_with_macro_callsite(cx, some_body, "..")),
+ none_expr: format!("{}{}", if method_sugg == "map_or" { "" } else { "|| " }, Sugg::hir_with_macro_callsite(cx, none_body, "..")),
})
} else {
None
projects / rust.git / blobdiff