diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs index 1311cc8968af0..fc674520295fe 100644 --- a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs @@ -1744,7 +1744,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { Ty::new_unit(self.tcx), ); } - if !self.consider_removing_semicolon(blk, expected_ty, err) { + if !self.err_ctxt().consider_removing_semicolon( + blk, + expected_ty, + err, + ) { self.err_ctxt().consider_returning_binding( blk, expected_ty, diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs index ccd9b38bf62ab..809102557acaa 100644 --- a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs @@ -22,7 +22,7 @@ use rustc_hir::{ Path, QPath, Stmt, StmtKind, TyKind, WherePredicate, }; use rustc_hir_analysis::astconv::AstConv; -use rustc_infer::traits::{self, StatementAsExpression}; +use rustc_infer::traits::{self}; use rustc_middle::lint::in_external_macro; use rustc_middle::middle::stability::EvalResult; use rustc_middle::ty::print::with_no_trimmed_paths; @@ -1791,45 +1791,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } } - /// A common error is to add an extra semicolon: - /// - /// ```compile_fail,E0308 - /// fn foo() -> usize { - /// 22; - /// } - /// ``` - /// - /// This routine checks if the final statement in a block is an - /// expression with an explicit semicolon whose type is compatible - /// with `expected_ty`. If so, it suggests removing the semicolon. - pub(crate) fn consider_removing_semicolon( - &self, - blk: &'tcx hir::Block<'tcx>, - expected_ty: Ty<'tcx>, - err: &mut Diag<'_>, - ) -> bool { - if let Some((span_semi, boxed)) = self.err_ctxt().could_remove_semicolon(blk, expected_ty) { - if let StatementAsExpression::NeedsBoxing = boxed { - err.span_suggestion_verbose( - span_semi, - "consider removing this semicolon and boxing the expression", - "", - Applicability::HasPlaceholders, - ); - } else { - err.span_suggestion_short( - span_semi, - "remove this semicolon to return this value", - "", - Applicability::MachineApplicable, - ); - } - true - } else { - false - } - } - pub(crate) fn is_field_suggestable( &self, field: &ty::FieldDef, diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs index af1aa346c0922..342f18a18dcc2 100644 --- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs +++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs @@ -1989,6 +1989,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { self.suggest_accessing_field_where_appropriate(cause, &exp_found, diag); self.suggest_await_on_expect_found(cause, span, &exp_found, diag); self.suggest_function_pointers(cause, span, &exp_found, diag); + self.suggest_turning_stmt_into_expr(cause, &exp_found, diag); } } diff --git a/compiler/rustc_infer/src/infer/error_reporting/suggest.rs b/compiler/rustc_infer/src/infer/error_reporting/suggest.rs index cfe8b75bdd76b..472dab639d590 100644 --- a/compiler/rustc_infer/src/infer/error_reporting/suggest.rs +++ b/compiler/rustc_infer/src/infer/error_reporting/suggest.rs @@ -1,8 +1,13 @@ +use crate::infer::error_reporting::hir::Path; use hir::def::CtorKind; use hir::intravisit::{walk_expr, walk_stmt, Visitor}; +use hir::{Local, QPath}; use rustc_data_structures::fx::FxIndexSet; use rustc_errors::{Applicability, Diag}; use rustc_hir as hir; +use rustc_hir::def::Res; +use rustc_hir::MatchSource; +use rustc_hir::Node; use rustc_middle::traits::{ IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode, StatementAsExpression, @@ -293,6 +298,97 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { } } + pub(super) fn suggest_turning_stmt_into_expr( + &self, + cause: &ObligationCause<'tcx>, + exp_found: &ty::error::ExpectedFound>, + diag: &mut Diag<'_>, + ) { + let ty::error::ExpectedFound { expected, found } = exp_found; + if !found.peel_refs().is_unit() { + return; + } + + let ObligationCauseCode::BlockTailExpression(hir_id, MatchSource::Normal) = cause.code() + else { + return; + }; + + let node = self.tcx.hir_node(*hir_id); + let mut blocks = vec![]; + if let hir::Node::Block(block) = node + && let Some(expr) = block.expr + && let hir::ExprKind::Path(QPath::Resolved(_, Path { res, .. })) = expr.kind + && let Res::Local(local) = res + && let Node::Local(Local { init: Some(init), .. }) = self.tcx.parent_hir_node(*local) + { + fn collect_blocks<'hir>(expr: &hir::Expr<'hir>, blocks: &mut Vec<&hir::Block<'hir>>) { + match expr.kind { + // `blk1` and `blk2` must be have the same types, it will be reported before reaching here + hir::ExprKind::If(_, blk1, Some(blk2)) => { + collect_blocks(blk1, blocks); + collect_blocks(blk2, blocks); + } + hir::ExprKind::Match(_, arms, _) => { + // all arms must have same types + for arm in arms.iter() { + collect_blocks(arm.body, blocks); + } + } + hir::ExprKind::Block(blk, _) => { + blocks.push(blk); + } + _ => {} + } + } + collect_blocks(init, &mut blocks); + } + + let expected_inner: Ty<'_> = expected.peel_refs(); + for block in blocks.iter() { + self.consider_removing_semicolon(block, expected_inner, diag); + } + } + + /// A common error is to add an extra semicolon: + /// + /// ```compile_fail,E0308 + /// fn foo() -> usize { + /// 22; + /// } + /// ``` + /// + /// This routine checks if the final statement in a block is an + /// expression with an explicit semicolon whose type is compatible + /// with `expected_ty`. If so, it suggests removing the semicolon. + pub fn consider_removing_semicolon( + &self, + blk: &'tcx hir::Block<'tcx>, + expected_ty: Ty<'tcx>, + diag: &mut Diag<'_>, + ) -> bool { + if let Some((span_semi, boxed)) = self.could_remove_semicolon(blk, expected_ty) { + if let StatementAsExpression::NeedsBoxing = boxed { + diag.span_suggestion_verbose( + span_semi, + "consider removing this semicolon and boxing the expression", + "", + Applicability::HasPlaceholders, + ); + } else { + diag.span_suggestion_short( + span_semi, + "remove this semicolon to return this value", + "", + Applicability::MachineApplicable, + ); + } + true + } else { + false + } + } + pub(super) fn suggest_function_pointers( &self, cause: &ObligationCause<'tcx>, diff --git a/tests/ui/inference/stmts-as-exp-105431.rs b/tests/ui/inference/stmts-as-exp-105431.rs new file mode 100644 index 0000000000000..b5adb4a2b6694 --- /dev/null +++ b/tests/ui/inference/stmts-as-exp-105431.rs @@ -0,0 +1,76 @@ +#![allow(unused)] + +fn test_if() -> i32 { + let x = if true { + eprintln!("hello"); + 3; + } + else { + 4; + }; + x //~ ERROR mismatched types +} + +fn test_if_without_binding() -> i32 { + if true { //~ ERROR mismatched types + eprintln!("hello"); + 3; + } + else { //~ ERROR mismatched types + 4; + } +} + +fn test_match() -> i32 { + let v = 1; + let res = match v { + 1 => { 1; } + _ => { 2; } + }; + res //~ ERROR mismatched types +} + +fn test_match_match_without_binding() -> i32 { + let v = 1; + match v { + 1 => { 1; } //~ ERROR mismatched types + _ => { 2; } //~ ERROR mismatched types + } +} + +fn test_match_arm_different_types() -> i32 { + let v = 1; + let res = match v { + 1 => { if 1 < 2 { 1 } else { 2 } } + _ => { 2; } //~ ERROR `match` arms have incompatible types + }; + res +} + +fn test_if_match_mixed() -> i32 { + let x = if true { + 3; + } else { + match 1 { + 1 => { 1 } + _ => { 2 } + }; + }; + x //~ ERROR mismatched types +} + +fn test_if_match_mixed_failed() -> i32 { + let x = if true { + 3; + } else { + // because this is a tailed expr, so we won't check deeper + match 1 { + 1 => { 33; } + _ => { 44; } + } + }; + x //~ ERROR mismatched types +} + + +fn main() {} diff --git a/tests/ui/inference/stmts-as-exp-105431.stderr b/tests/ui/inference/stmts-as-exp-105431.stderr new file mode 100644 index 0000000000000..f3da04b39a371 --- /dev/null +++ b/tests/ui/inference/stmts-as-exp-105431.stderr @@ -0,0 +1,129 @@ +error[E0308]: mismatched types + --> $DIR/stmts-as-exp-105431.rs:11:5 + | +LL | fn test_if() -> i32 { + | --- expected `i32` because of return type +... +LL | x + | ^ expected `i32`, found `()` + | +help: remove this semicolon to return this value + | +LL - 3; +LL + 3 + | +help: remove this semicolon to return this value + | +LL - 4; +LL + 4 + | + +error[E0308]: mismatched types + --> $DIR/stmts-as-exp-105431.rs:15:13 + | +LL | if true { + | _____________^ +LL | | eprintln!("hello"); +LL | | 3; + | | - help: remove this semicolon to return this value +LL | | } + | |_____^ expected `i32`, found `()` + +error[E0308]: mismatched types + --> $DIR/stmts-as-exp-105431.rs:19:10 + | +LL | else { + | __________^ +LL | | 4; + | | - help: remove this semicolon to return this value +LL | | } + | |_____^ expected `i32`, found `()` + +error[E0308]: mismatched types + --> $DIR/stmts-as-exp-105431.rs:30:5 + | +LL | fn test_match() -> i32 { + | --- expected `i32` because of return type +... +LL | res + | ^^^ expected `i32`, found `()` + | +help: remove this semicolon to return this value + | +LL - 1 => { 1; } +LL + 1 => { 1 } + | +help: remove this semicolon to return this value + | +LL - _ => { 2; } +LL + _ => { 2 } + | + +error[E0308]: mismatched types + --> $DIR/stmts-as-exp-105431.rs:36:14 + | +LL | 1 => { 1; } + | ^^^-^^ + | | | + | | help: remove this semicolon to return this value + | expected `i32`, found `()` + +error[E0308]: mismatched types + --> $DIR/stmts-as-exp-105431.rs:37:14 + | +LL | _ => { 2; } + | ^^^-^^ + | | | + | | help: remove this semicolon to return this value + | expected `i32`, found `()` + +error[E0308]: `match` arms have incompatible types + --> $DIR/stmts-as-exp-105431.rs:45:16 + | +LL | let res = match v { + | _______________- +LL | | 1 => { if 1 < 2 { 1 } else { 2 } } + | | ------------------------- this is found to be of type `{integer}` +LL | | _ => { 2; } + | | ^- + | | || + | | |help: consider removing this semicolon + | | expected integer, found `()` +LL | | }; + | |_____- `match` arms have incompatible types + +error[E0308]: mismatched types + --> $DIR/stmts-as-exp-105431.rs:59:5 + | +LL | fn test_if_match_mixed() -> i32 { + | --- expected `i32` because of return type +... +LL | x + | ^ expected `i32`, found `()` + | +help: remove this semicolon to return this value + | +LL - 3; +LL + 3 + | +help: remove this semicolon to return this value + | +LL - }; +LL + } + | + +error[E0308]: mismatched types + --> $DIR/stmts-as-exp-105431.rs:72:5 + | +LL | fn test_if_match_mixed_failed() -> i32 { + | --- expected `i32` because of return type +LL | let x = if true { +LL | 3; + | - help: remove this semicolon to return this value +... +LL | x + | ^ expected `i32`, found `()` + +error: aborting due to 9 previous errors + +For more information about this error, try `rustc --explain E0308`.