-use rustc::lint::*;
-use rustc::hir::*;
+use if_chain::if_chain;
use rustc::hir::def::Def;
-use crate::utils::sugg::Sugg;
+use rustc::hir::*;
+use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
+use rustc::{declare_tool_lint, lint_array};
+use rustc_errors::Applicability;
use syntax::ptr::P;
-use crate::utils::{match_def_path, match_type, span_lint_and_then};
use crate::utils::paths::*;
+use crate::utils::sugg::Sugg;
+use crate::utils::{match_def_path, match_type, span_lint_and_then, SpanlessEq};
-/// **What it does:** Checks for expressions that could be replaced by the question mark operator
-///
-/// **Why is this bad?** Question mark usage is more idiomatic
-///
-/// **Known problems:** None
-///
-/// **Example:**
-/// ```rust
-/// if option.is_none() {
-/// return None;
-/// }
-/// ```
-///
-/// Could be written:
-///
-/// ```rust
-/// option?;
-/// ```
-declare_clippy_lint!{
+declare_clippy_lint! {
+ /// **What it does:** Checks for expressions that could be replaced by the question mark operator.
+ ///
+ /// **Why is this bad?** Question mark usage is more idiomatic.
+ ///
+ /// **Known problems:** None
+ ///
+ /// **Example:**
+ /// ```ignore
+ /// if option.is_none() {
+ /// return None;
+ /// }
+ /// ```
+ ///
+ /// Could be written:
+ ///
+ /// ```ignore
+ /// option?;
+ /// ```
pub QUESTION_MARK,
style,
"checks for expressions that could be replaced by the question mark operator"
}
#[derive(Copy, Clone)]
-pub struct QuestionMarkPass;
+pub struct Pass;
-impl LintPass for QuestionMarkPass {
+impl LintPass for Pass {
fn get_lints(&self) -> LintArray {
lint_array!(QUESTION_MARK)
}
+
+ fn name(&self) -> &'static str {
+ "QuestionMark"
+ }
}
-impl QuestionMarkPass {
- /// Check if the given expression on the given context matches the following structure:
+impl Pass {
+ /// Checks if the given expression on the given context matches the following structure:
///
/// ```ignore
/// if option.is_none() {
/// ```
///
/// If it matches, it will suggest to use the question mark operator instead
- fn check_is_none_and_early_return_none(cx: &LateContext, expr: &Expr) {
+ fn check_is_none_and_early_return_none(cx: &LateContext<'_, '_>, expr: &Expr) {
if_chain! {
- if let ExprIf(ref if_expr, ref body, _) = expr.node;
- if let ExprMethodCall(ref segment, _, ref args) = if_expr.node;
+ if let ExprKind::If(if_expr, body, else_) = &expr.node;
+ if let ExprKind::MethodCall(segment, _, args) = &if_expr.node;
if segment.ident.name == "is_none";
if Self::expression_returns_none(cx, body);
if let Some(subject) = args.get(0);
if Self::is_option(cx, subject);
then {
- span_lint_and_then(
- cx,
- QUESTION_MARK,
- expr.span,
- "this block may be rewritten with the `?` operator",
- |db| {
- let receiver_str = &Sugg::hir(cx, subject, "..");
-
- db.span_suggestion(
- expr.span,
- "replace_it_with",
- format!("{}?;", receiver_str),
- );
+ let receiver_str = &Sugg::hir(cx, subject, "..");
+ let mut replacement: Option<String> = None;
+ if let Some(else_) = else_ {
+ if_chain! {
+ if let ExprKind::Block(block, None) = &else_.node;
+ if block.stmts.len() == 0;
+ if let Some(block_expr) = &block.expr;
+ if SpanlessEq::new(cx).ignore_fn().eq_expr(subject, block_expr);
+ then {
+ replacement = Some(format!("Some({}?)", receiver_str));
+ }
}
- )
+ } else if Self::moves_by_default(cx, subject) {
+ replacement = Some(format!("{}.as_ref()?;", receiver_str));
+ } else {
+ replacement = Some(format!("{}?;", receiver_str));
+ }
+
+ if let Some(replacement_str) = replacement {
+ span_lint_and_then(
+ cx,
+ QUESTION_MARK,
+ expr.span,
+ "this block may be rewritten with the `?` operator",
+ |db| {
+ db.span_suggestion(
+ expr.span,
+ "replace_it_with",
+ replacement_str,
+ Applicability::MaybeIncorrect, // snippet
+ );
+ }
+ )
+ }
}
}
}
- fn is_option(cx: &LateContext, expression: &Expr) -> bool {
+ fn moves_by_default(cx: &LateContext<'_, '_>, expression: &Expr) -> bool {
+ let expr_ty = cx.tables.expr_ty(expression);
+
+ !expr_ty.is_copy_modulo_regions(cx.tcx, cx.param_env, expression.span)
+ }
+
+ fn is_option(cx: &LateContext<'_, '_>, expression: &Expr) -> bool {
let expr_ty = cx.tables.expr_ty(expression);
match_type(cx, expr_ty, &OPTION)
}
- fn expression_returns_none(cx: &LateContext, expression: &Expr) -> bool {
+ fn expression_returns_none(cx: &LateContext<'_, '_>, expression: &Expr) -> bool {
match expression.node {
- ExprBlock(ref block, _) => {
+ ExprKind::Block(ref block, _) => {
if let Some(return_expression) = Self::return_expression(block) {
return Self::expression_returns_none(cx, &return_expression);
}
false
},
- ExprRet(Some(ref expr)) => {
- Self::expression_returns_none(cx, expr)
- },
- ExprPath(ref qp) => {
+ ExprKind::Ret(Some(ref expr)) => Self::expression_returns_none(cx, expr),
+ ExprKind::Path(ref qp) => {
if let Def::VariantCtor(def_id, _) = cx.tables.qpath_def(qp, expression.hir_id) {
- return match_def_path(cx.tcx, def_id, &OPTION_NONE);
+ return match_def_path(cx.tcx, def_id, &OPTION_NONE);
}
false
},
- _ => false
+ _ => false,
}
}
if_chain! {
if block.stmts.len() == 1;
if let Some(expr) = block.stmts.iter().last();
- if let StmtSemi(ref expr, _) = expr.node;
- if let ExprRet(ref ret_expr) = expr.node;
+ if let StmtKind::Semi(ref expr) = expr.node;
+ if let ExprKind::Ret(ref ret_expr) = expr.node;
if let &Some(ref ret_expr) = ret_expr;
then {
}
}
- // Check if the block has an implicit return expression
- if let Some(ref ret_expr) = block.expr {
- return Some(ret_expr.clone());
+ // Check for `return` without a semicolon.
+ if_chain! {
+ if block.stmts.len() == 0;
+ if let Some(ExprKind::Ret(Some(ret_expr))) = block.expr.as_ref().map(|e| &e.node);
+ then {
+ return Some(ret_expr.clone());
+ }
}
None
}
}
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for QuestionMarkPass {
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
Self::check_is_none_and_early_return_none(cx, expr);
}
projects / rust.git / blobdiff