diff options
| -rw-r--r-- | clippy_lints/src/implicit_return.rs | 165 | ||||
| -rw-r--r-- | tests/ui/implicit_return.rs | 14 | ||||
| -rw-r--r-- | tests/ui/implicit_return.stderr | 34 |
3 files changed, 137 insertions, 76 deletions
diff --git a/clippy_lints/src/implicit_return.rs b/clippy_lints/src/implicit_return.rs index e280ce4c80b..409a10f82eb 100644 --- a/clippy_lints/src/implicit_return.rs +++ b/clippy_lints/src/implicit_return.rs @@ -1,9 +1,16 @@ -use crate::utils::{in_macro_or_desugar, is_expn_of, snippet_opt, span_lint_and_then}; -use rustc::hir::{intravisit::FnKind, Body, ExprKind, FnDecl, HirId, MatchSource}; -use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass}; -use rustc::{declare_lint_pass, declare_tool_lint}; +use crate::utils::{ + in_macro_or_desugar, match_def_path, + paths::{BEGIN_PANIC, BEGIN_PANIC_FMT}, + resolve_node, snippet_opt, span_lint_and_then, +}; +use if_chain::if_chain; +use rustc::{ + declare_lint_pass, declare_tool_lint, + hir::{intravisit::FnKind, Body, Expr, ExprKind, FnDecl, HirId, MatchSource, StmtKind}, + lint::{LateContext, LateLintPass, LintArray, LintPass}, +}; use rustc_errors::Applicability; -use syntax::source_map::Span; +use syntax_pos::Span; declare_clippy_lint! { /// **What it does:** Checks for missing return statements at the end of a block. @@ -35,71 +42,98 @@ declare_clippy_lint! { declare_lint_pass!(ImplicitReturn => [IMPLICIT_RETURN]); -impl ImplicitReturn { - fn lint(cx: &LateContext<'_, '_>, outer_span: syntax_pos::Span, inner_span: syntax_pos::Span, msg: &str) { - span_lint_and_then(cx, IMPLICIT_RETURN, outer_span, "missing return statement", |db| { - if let Some(snippet) = snippet_opt(cx, inner_span) { - db.span_suggestion( - outer_span, - msg, - format!("return {}", snippet), - Applicability::MachineApplicable, - ); - } - }); +fn lint(cx: &LateContext<'_, '_>, outer_span: Span, inner_span: Span, msg: &str) { + let outer_span = span_to_outer_expn(outer_span); + let inner_span = span_to_outer_expn(inner_span); + + span_lint_and_then(cx, IMPLICIT_RETURN, outer_span, "missing return statement", |db| { + if let Some(snippet) = snippet_opt(cx, inner_span) { + db.span_suggestion( + outer_span, + msg, + format!("return {}", snippet), + Applicability::MachineApplicable, + ); + } + }); +} + +fn span_to_outer_expn(span: Span) -> Span { + if let Some(expr) = span.ctxt().outer_expn_info() { + span_to_outer_expn(expr.call_site) + } else { + span } +} - fn expr_match(cx: &LateContext<'_, '_>, expr: &rustc::hir::Expr) { - match &expr.node { - // loops could be using `break` instead of `return` - ExprKind::Block(block, ..) | ExprKind::Loop(block, ..) => { - if let Some(expr) = &block.expr { - Self::expr_match(cx, expr); - } - // only needed in the case of `break` with `;` at the end - else if let Some(stmt) = block.stmts.last() { - if let rustc::hir::StmtKind::Semi(expr, ..) = &stmt.node { - // make sure it's a break, otherwise we want to skip - if let ExprKind::Break(.., break_expr) = &expr.node { - if let Some(break_expr) = break_expr { - Self::lint(cx, expr.span, break_expr.span, "change `break` to `return` as shown"); - } - } +fn expr_match(cx: &LateContext<'_, '_>, expr: &Expr, ret_ty_is_never: bool) { + match &expr.node { + // loops could be using `break` instead of `return` + ExprKind::Block(block, ..) | ExprKind::Loop(block, ..) => { + if let Some(expr) = &block.expr { + expr_match(cx, expr, ret_ty_is_never); + } + // only needed in the case of `break` with `;` at the end + else if let Some(stmt) = block.stmts.last() { + if_chain! { + if let StmtKind::Semi(expr, ..) = &stmt.node; + // make sure it's a break, otherwise we want to skip + if let ExprKind::Break(.., break_expr) = &expr.node; + if let Some(break_expr) = break_expr; + then { + lint(cx, expr.span, break_expr.span, "change `break` to `return` as shown"); } } - }, - // use `return` instead of `break` - ExprKind::Break(.., break_expr) => { - if let Some(break_expr) = break_expr { - Self::lint(cx, expr.span, break_expr.span, "change `break` to `return` as shown"); - } - }, - ExprKind::Match(.., arms, source) => { - let check_all_arms = match source { - MatchSource::IfLetDesugar { - contains_else_clause: has_else, - } => *has_else, - _ => true, - }; + } + }, + // use `return` instead of `break` + ExprKind::Break(.., break_expr) => { + if let Some(break_expr) = break_expr { + lint(cx, expr.span, break_expr.span, "change `break` to `return` as shown"); + } + }, + ExprKind::Match(.., arms, source) => { + let check_all_arms = match source { + MatchSource::IfLetDesugar { + contains_else_clause: has_else, + } => *has_else, + _ => true, + }; - if check_all_arms { - for arm in arms { - Self::expr_match(cx, &arm.body); + if check_all_arms { + for arm in arms { + expr_match(cx, &arm.body, ret_ty_is_never); + } + } else { + expr_match( + cx, + &arms.first().expect("if let doesn't have a single arm").body, + ret_ty_is_never, + ); + } + }, + // skip if it already has a return statement + ExprKind::Ret(..) => (), + // make sure it's not a call that panics unless we intend to return a panic + ExprKind::Call(expr, ..) => { + if_chain! { + if let ExprKind::Path(qpath) = &expr.node; + if let Some(path_def_id) = resolve_node(cx, qpath, expr.hir_id).opt_def_id(); + if match_def_path(cx, path_def_id, &BEGIN_PANIC) || + match_def_path(cx, path_def_id, &BEGIN_PANIC_FMT); + then { + // only put `return` on panics if the return type of the function/closure is a panic + if ret_ty_is_never { + lint(cx, expr.span, expr.span, "add `return` as shown") } - } else { - Self::expr_match(cx, &arms.first().expect("if let doesn't have a single arm").body); } - }, - // skip if it already has a return statement - ExprKind::Ret(..) => (), - // everything else is missing `return` - _ => { - // make sure it's not just an unreachable expression - if is_expn_of(expr.span, "unreachable").is_none() { - Self::lint(cx, expr.span, expr.span, "add `return` as shown") + else { + lint(cx, expr.span, expr.span, "add `return` as shown") } - }, - } + } + }, + // everything else is missing `return` + _ => lint(cx, expr.span, expr.span, "add `return` as shown"), } } @@ -110,16 +144,17 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ImplicitReturn { _: FnKind<'tcx>, _: &'tcx FnDecl, body: &'tcx Body, - span: Span, + span: syntax::source_map::Span, _: HirId, ) { let def_id = cx.tcx.hir().body_owner_def_id(body.id()); let mir = cx.tcx.optimized_mir(def_id); + let ret_ty = mir.return_ty(); // checking return type through MIR, HIR is not able to determine inferred closure return types // make sure it's not a macro - if !mir.return_ty().is_unit() && !in_macro_or_desugar(span) { - Self::expr_match(cx, &body.value); + if !ret_ty.is_unit() && !in_macro_or_desugar(span) { + expr_match(cx, &body.value, ret_ty.is_never()); } } } diff --git a/tests/ui/implicit_return.rs b/tests/ui/implicit_return.rs index d1c63ca1697..ade3dc00a53 100644 --- a/tests/ui/implicit_return.rs +++ b/tests/ui/implicit_return.rs @@ -5,6 +5,7 @@ fn test_end_of_fn() -> bool { // no error! return true; } + true } @@ -76,6 +77,18 @@ fn test_closure() { let _ = || true; } +fn test_return_never() -> ! { + panic!() +} + +fn test_panic() -> bool { + panic!() +} + +fn test_return_macro() -> String { + format!("test {}", "test") +} + fn main() { let _ = test_end_of_fn(); let _ = test_if_block(); @@ -86,4 +99,5 @@ fn main() { let _ = test_loop_with_nests(); let _ = test_loop_with_if_let(); test_closure(); + let _ = test_return_macro(); } diff --git a/tests/ui/implicit_return.stderr b/tests/ui/implicit_return.stderr index 98b588f1a74..ac6a76cd39c 100644 --- a/tests/ui/implicit_return.stderr +++ b/tests/ui/implicit_return.stderr @@ -1,5 +1,5 @@ error: missing return statement - --> $DIR/implicit_return.rs:8:5 + --> $DIR/implicit_return.rs:9:5 | LL | true | ^^^^ help: add `return` as shown: `return true` @@ -7,58 +7,70 @@ LL | true = note: `-D clippy::implicit-return` implied by `-D warnings` error: missing return statement - --> $DIR/implicit_return.rs:14:9 + --> $DIR/implicit_return.rs:15:9 | LL | true | ^^^^ help: add `return` as shown: `return true` error: missing return statement - --> $DIR/implicit_return.rs:16:9 + --> $DIR/implicit_return.rs:17:9 | LL | false | ^^^^^ help: add `return` as shown: `return false` error: missing return statement - --> $DIR/implicit_return.rs:24:17 + --> $DIR/implicit_return.rs:25:17 | LL | true => false, | ^^^^^ help: add `return` as shown: `return false` error: missing return statement - --> $DIR/implicit_return.rs:25:20 + --> $DIR/implicit_return.rs:26:20 | LL | false => { true }, | ^^^^ help: add `return` as shown: `return true` error: missing return statement - --> $DIR/implicit_return.rs:40:9 + --> $DIR/implicit_return.rs:41:9 | LL | break true; | ^^^^^^^^^^ help: change `break` to `return` as shown: `return true` error: missing return statement - --> $DIR/implicit_return.rs:48:13 + --> $DIR/implicit_return.rs:49:13 | LL | break true; | ^^^^^^^^^^ help: change `break` to `return` as shown: `return true` error: missing return statement - --> $DIR/implicit_return.rs:57:13 + --> $DIR/implicit_return.rs:58:13 | LL | break true; | ^^^^^^^^^^ help: change `break` to `return` as shown: `return true` error: missing return statement - --> $DIR/implicit_return.rs:75:18 + --> $DIR/implicit_return.rs:76:18 | LL | let _ = || { true }; | ^^^^ help: add `return` as shown: `return true` error: missing return statement - --> $DIR/implicit_return.rs:76:16 + --> $DIR/implicit_return.rs:77:16 | LL | let _ = || true; | ^^^^ help: add `return` as shown: `return true` -error: aborting due to 10 previous errors +error: missing return statement + --> $DIR/implicit_return.rs:81:5 + | +LL | panic!() + | ^^^^^^^^ help: add `return` as shown: `return panic!()` + +error: missing return statement + --> $DIR/implicit_return.rs:89:5 + | +LL | format!("test {}", "test") + | ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add `return` as shown: `return format!("test {}", "test")` + +error: aborting due to 12 previous errors |