From b1dcdd198b8b92925560800b812b95a4ab1a97bb Mon Sep 17 00:00:00 2001 From: yukang Date: Sat, 17 Jan 2026 21:27:43 +0800 Subject: [PATCH 1/3] Try to recover from over-parsing in const item when a semicolon is missing --- compiler/rustc_parse/src/errors.rs | 1 - compiler/rustc_parse/src/parser/item.rs | 43 +++++++++++++++ .../issues/const-recover-semi-issue-151149.rs | 30 +++++++++++ .../const-recover-semi-issue-151149.stderr | 52 +++++++++++++++++++ 4 files changed, 125 insertions(+), 1 deletion(-) create mode 100644 tests/ui/issues/const-recover-semi-issue-151149.rs create mode 100644 tests/ui/issues/const-recover-semi-issue-151149.stderr diff --git a/compiler/rustc_parse/src/errors.rs b/compiler/rustc_parse/src/errors.rs index 60e4a240c85e9..59c61cb21e8f9 100644 --- a/compiler/rustc_parse/src/errors.rs +++ b/compiler/rustc_parse/src/errors.rs @@ -1284,7 +1284,6 @@ pub(crate) struct HelpIdentifierStartsWithNumber { pub(crate) struct ExpectedSemi { pub span: Span, pub token: Token, - pub unexpected_token_label: Option, pub sugg: ExpectedSemiSugg, } diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs index bc76418429aac..1bd7a3eda9005 100644 --- a/compiler/rustc_parse/src/parser/item.rs +++ b/compiler/rustc_parse/src/parser/item.rs @@ -6,6 +6,7 @@ use rustc_ast::ast::*; use rustc_ast::token::{self, Delimiter, InvisibleOrigin, MetaVarKind, TokenKind}; use rustc_ast::tokenstream::{DelimSpan, TokenStream, TokenTree}; use rustc_ast::util::case::Case; +use rustc_ast::util::classify; use rustc_ast::{ attr, {self as ast}, }; @@ -1571,6 +1572,9 @@ impl<'a> Parser<'a> { generics.where_clause = where_clause; + if let Some(recovered_rhs) = self.try_recover_const_missing_semi(&rhs) { + return Ok((ident, generics, ty, Some(ConstItemRhs::Body(recovered_rhs)))); + } self.expect_semi()?; Ok((ident, generics, ty, rhs)) @@ -3407,6 +3411,45 @@ impl<'a> Parser<'a> { Ok(Some(_)) ) } + + /// Try to recover from over-parsing in const item when a semicolon is missing. + /// + /// This detects cases where we parsed too much because a semicolon was missing + /// and the next line started an expression that the parser treated as a continuation + /// (e.g., `foo() \n &bar` was parsed as `foo() & bar`). + /// + /// Returns a corrected expression if recovery is successful. + fn try_recover_const_missing_semi(&mut self, rhs: &Option) -> Option> { + if self.token == TokenKind::Semi { + return None; + } + let Some(ConstItemRhs::Body(rhs)) = rhs else { + return None; + }; + if !self.may_recover() || rhs.span.from_expansion() { + return None; + } + let sm = self.psess.source_map(); + // Check if this is a binary expression that spans multiple lines + // and the RHS looks like it could be an independent expression. + if let ExprKind::Binary(op, lhs, rhs_inner) = &rhs.kind + && sm.is_multiline(lhs.span.shrink_to_hi().until(rhs_inner.span.shrink_to_lo())) + && matches!(op.node, BinOpKind::Mul | BinOpKind::BitAnd) + && classify::expr_requires_semi_to_be_stmt(rhs_inner) + { + let lhs_end_span = lhs.span.shrink_to_hi(); + let guar = self.dcx().emit_err(errors::ExpectedSemi { + span: lhs_end_span, + token: self.token, + unexpected_token_label: Some(self.token.span), + sugg: errors::ExpectedSemiSugg::AddSemi(lhs_end_span), + }); + + Some(self.mk_expr(lhs.span, ExprKind::Err(guar))) + } else { + None + } + } } enum IsMacroRulesItem { diff --git a/tests/ui/issues/const-recover-semi-issue-151149.rs b/tests/ui/issues/const-recover-semi-issue-151149.rs new file mode 100644 index 0000000000000..f5dc27bb3dd86 --- /dev/null +++ b/tests/ui/issues/const-recover-semi-issue-151149.rs @@ -0,0 +1,30 @@ +#![feature(const_trait_impl)] + +const trait ConstDefault { + fn const_default() -> Self; +} + +impl const ConstDefault for u8 { + fn const_default() -> Self { 0 } +} + +const fn val() -> u8 { + 42 +} + +const fn foo() -> &'static u8 { //~ ERROR mismatched types + const C: u8 = u8::const_default() //~ ERROR expected `;` + &C +} + +const fn bar() -> u8 { //~ ERROR mismatched types + const C: u8 = 1 + + 2 //~ ERROR expected `;` +} + +const fn baz() -> u8 { //~ ERROR mismatched types + const C: u8 = 1 + + val() //~ ERROR expected `;` +} + +fn main() {} diff --git a/tests/ui/issues/const-recover-semi-issue-151149.stderr b/tests/ui/issues/const-recover-semi-issue-151149.stderr new file mode 100644 index 0000000000000..96c62c39fb6ad --- /dev/null +++ b/tests/ui/issues/const-recover-semi-issue-151149.stderr @@ -0,0 +1,52 @@ +error: expected `;`, found `}` + --> $DIR/const-recover-semi-issue-151149.rs:16:38 + | +LL | const C: u8 = u8::const_default() + | ^ help: add `;` here +LL | &C +LL | } + | - unexpected token + +error: expected `;`, found `}` + --> $DIR/const-recover-semi-issue-151149.rs:22:9 + | +LL | + 2 + | ^ help: add `;` here +LL | } + | - unexpected token + +error: expected `;`, found `}` + --> $DIR/const-recover-semi-issue-151149.rs:27:13 + | +LL | + val() + | ^ help: add `;` here +LL | } + | - unexpected token + +error[E0308]: mismatched types + --> $DIR/const-recover-semi-issue-151149.rs:15:19 + | +LL | const fn foo() -> &'static u8 { + | --- ^^^^^^^^^^^ expected `&u8`, found `()` + | | + | implicitly returns `()` as its body has no tail or `return` expression + +error[E0308]: mismatched types + --> $DIR/const-recover-semi-issue-151149.rs:20:19 + | +LL | const fn bar() -> u8 { + | --- ^^ expected `u8`, found `()` + | | + | implicitly returns `()` as its body has no tail or `return` expression + +error[E0308]: mismatched types + --> $DIR/const-recover-semi-issue-151149.rs:25:19 + | +LL | const fn baz() -> u8 { + | --- ^^ expected `u8`, found `()` + | | + | implicitly returns `()` as its body has no tail or `return` expression + +error: aborting due to 6 previous errors + +For more information about this error, try `rustc --explain E0308`. From 68d28b567cd706d2e6429dc6762c3775a4f9c29a Mon Sep 17 00:00:00 2001 From: yukang Date: Mon, 19 Jan 2026 15:17:03 +0800 Subject: [PATCH 2/3] also add recover from over parsing for let --- compiler/rustc_parse/src/parser/item.rs | 31 ++--- compiler/rustc_parse/src/parser/mod.rs | 68 ++++++++- compiler/rustc_parse/src/parser/stmt.rs | 130 ++++++++++-------- .../const-recover-semi-issue-151149.stderr | 52 ------- .../const-recover-semi-issue-151149.rs | 12 +- .../const-recover-semi-issue-151149.stderr | 100 ++++++++++++++ 6 files changed, 257 insertions(+), 136 deletions(-) delete mode 100644 tests/ui/issues/const-recover-semi-issue-151149.stderr rename tests/ui/{issues => parser}/const-recover-semi-issue-151149.rs (67%) create mode 100644 tests/ui/parser/const-recover-semi-issue-151149.stderr diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs index 1bd7a3eda9005..0c29f56e2bb43 100644 --- a/compiler/rustc_parse/src/parser/item.rs +++ b/compiler/rustc_parse/src/parser/item.rs @@ -6,7 +6,6 @@ use rustc_ast::ast::*; use rustc_ast::token::{self, Delimiter, InvisibleOrigin, MetaVarKind, TokenKind}; use rustc_ast::tokenstream::{DelimSpan, TokenStream, TokenTree}; use rustc_ast::util::case::Case; -use rustc_ast::util::classify; use rustc_ast::{ attr, {self as ast}, }; @@ -2654,8 +2653,13 @@ impl<'a> Parser<'a> { *sig_hi = self.prev_token.span; (AttrVec::new(), None) } else if self.check(exp!(OpenBrace)) || self.token.is_metavar_block() { - self.parse_block_common(self.token.span, BlockCheckMode::Default, None) - .map(|(attrs, body)| (attrs, Some(body)))? + let prev_in_fn_body = self.in_fn_body; + self.in_fn_body = true; + let res = self + .parse_block_common(self.token.span, BlockCheckMode::Default, None) + .map(|(attrs, body)| (attrs, Some(body))); + self.in_fn_body = prev_in_fn_body; + res? } else if self.token == token::Eq { // Recover `fn foo() = $expr;`. self.bump(); // `=` @@ -3426,26 +3430,11 @@ impl<'a> Parser<'a> { let Some(ConstItemRhs::Body(rhs)) = rhs else { return None; }; - if !self.may_recover() || rhs.span.from_expansion() { + if !self.in_fn_body || !self.may_recover() || rhs.span.from_expansion() { return None; } - let sm = self.psess.source_map(); - // Check if this is a binary expression that spans multiple lines - // and the RHS looks like it could be an independent expression. - if let ExprKind::Binary(op, lhs, rhs_inner) = &rhs.kind - && sm.is_multiline(lhs.span.shrink_to_hi().until(rhs_inner.span.shrink_to_lo())) - && matches!(op.node, BinOpKind::Mul | BinOpKind::BitAnd) - && classify::expr_requires_semi_to_be_stmt(rhs_inner) - { - let lhs_end_span = lhs.span.shrink_to_hi(); - let guar = self.dcx().emit_err(errors::ExpectedSemi { - span: lhs_end_span, - token: self.token, - unexpected_token_label: Some(self.token.span), - sugg: errors::ExpectedSemiSugg::AddSemi(lhs_end_span), - }); - - Some(self.mk_expr(lhs.span, ExprKind::Err(guar))) + if let Some((span, guar)) = self.missing_semi_from_binop("const", rhs) { + Some(self.mk_expr(span, ExprKind::Err(guar))) } else { None } diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs index d6e99bc540f74..52ab956ddcc9a 100644 --- a/compiler/rustc_parse/src/parser/mod.rs +++ b/compiler/rustc_parse/src/parser/mod.rs @@ -34,17 +34,18 @@ use rustc_ast::tokenstream::{ ParserRange, ParserReplacement, Spacing, TokenCursor, TokenStream, TokenTree, TokenTreeCursor, }; use rustc_ast::util::case::Case; +use rustc_ast::util::classify; use rustc_ast::{ - self as ast, AnonConst, AttrArgs, AttrId, BlockCheckMode, ByRef, Const, CoroutineKind, - DUMMY_NODE_ID, DelimArgs, Expr, ExprKind, Extern, HasAttrs, HasTokens, MgcaDisambiguation, - Mutability, Recovered, Safety, StrLit, Visibility, VisibilityKind, + self as ast, AnonConst, AttrArgs, AttrId, BinOpKind, BlockCheckMode, ByRef, Const, + CoroutineKind, DUMMY_NODE_ID, DelimArgs, Expr, ExprKind, Extern, HasAttrs, HasTokens, + MgcaDisambiguation, Mutability, Recovered, Safety, StrLit, Visibility, VisibilityKind, }; use rustc_ast_pretty::pprust; use rustc_data_structures::fx::FxHashMap; use rustc_errors::{Applicability, Diag, FatalError, MultiSpan, PResult}; use rustc_index::interval::IntervalSet; use rustc_session::parse::ParseSess; -use rustc_span::{Ident, Span, Symbol, kw, sym}; +use rustc_span::{ErrorGuaranteed, Ident, Span, Symbol, kw, sym}; use thin_vec::ThinVec; use token_type::TokenTypeSet; pub use token_type::{ExpKeywordPair, ExpTokenPair, TokenType}; @@ -223,6 +224,8 @@ pub struct Parser<'a> { /// Whether the parser is allowed to do recovery. /// This is disabled when parsing macro arguments, see #103534 recovery: Recovery, + /// Whether we're parsing a function body. + in_fn_body: bool, } // This type is used a lot, e.g. it's cloned when matching many declarative macro rules with @@ -372,6 +375,7 @@ impl<'a> Parser<'a> { }, current_closure: None, recovery: Recovery::Allowed, + in_fn_body: false, }; // Make parser point to the first token. @@ -1683,6 +1687,62 @@ impl<'a> Parser<'a> { _ => self.prev_token.span, } } + + fn missing_semi_from_binop( + &self, + kind_desc: &str, + expr: &Expr, + ) -> Option<(Span, ErrorGuaranteed)> { + if self.token == TokenKind::Semi { + return None; + } + if !self.may_recover() || expr.span.from_expansion() { + return None; + } + let sm = self.psess.source_map(); + if let ExprKind::Binary(op, lhs, rhs) = &expr.kind + && sm.is_multiline(lhs.span.shrink_to_hi().until(rhs.span.shrink_to_lo())) + && matches!(op.node, BinOpKind::Mul | BinOpKind::BitAnd) + && classify::expr_requires_semi_to_be_stmt(rhs) + { + let lhs_end_span = lhs.span.shrink_to_hi(); + let token_str = token_descr(&self.token); + let mut err = self + .dcx() + .struct_span_err(lhs_end_span, format!("expected `;`, found {token_str}")); + err.span_label(self.token.span, "unexpected token"); + + let continuation_span = lhs_end_span.until(rhs.span.shrink_to_hi()); + err.span_label( + continuation_span, + format!( + "to finish parsing this {kind_desc}, expected this to be followed by a `;`", + ), + ); + let op_desc = match op.node { + BinOpKind::BitAnd => "a bit-and", + BinOpKind::Mul => "a multiplication", + _ => "a binary", + }; + let mut note_spans = MultiSpan::new(); + note_spans.push_span_label(lhs.span, "parsed as the left-hand expression"); + note_spans.push_span_label(rhs.span, "parsed as the right-hand expression"); + note_spans.push_span_label(op.span, format!("this was parsed as {op_desc}")); + err.span_note( + note_spans, + format!("the {kind_desc} was parsed as having {op_desc} binary expression"), + ); + + err.span_suggestion( + lhs_end_span, + format!("you may have meant to write a `;` to terminate the {kind_desc} earlier"), + ";", + Applicability::MaybeIncorrect, + ); + return Some((lhs.span, err.emit())); + } + None + } } // Metavar captures of various kinds. diff --git a/compiler/rustc_parse/src/parser/stmt.rs b/compiler/rustc_parse/src/parser/stmt.rs index 26393bf61a32e..8d0de66aabf8d 100644 --- a/compiler/rustc_parse/src/parser/stmt.rs +++ b/compiler/rustc_parse/src/parser/stmt.rs @@ -923,6 +923,19 @@ impl<'a> Parser<'a> { } } + fn try_recover_let_missing_semi(&mut self, local: &mut Local) -> Option { + let expr = match &mut local.kind { + LocalKind::Init(expr) | LocalKind::InitElse(expr, _) => expr, + LocalKind::Decl => return None, + }; + if let Some((span, guar)) = self.missing_semi_from_binop("`let` binding", expr) { + *expr = self.mk_expr(span, ExprKind::Err(guar)); + return Some(guar); + } + + None + } + /// Parses a statement, including the trailing semicolon. pub fn parse_full_stmt( &mut self, @@ -1065,71 +1078,74 @@ impl<'a> Parser<'a> { } } StmtKind::Expr(_) | StmtKind::MacCall(_) => {} - StmtKind::Let(local) if let Err(mut e) = self.expect_semi() => { - // We might be at the `,` in `let x = foo;`. Try to recover. - match &mut local.kind { - LocalKind::Init(expr) | LocalKind::InitElse(expr, _) => { - self.check_mistyped_turbofish_with_multiple_type_params(e, expr).map_err( - |mut e| { - self.recover_missing_dot(&mut e); - self.recover_missing_let_else(&mut e, &local.pat, stmt.span); - e - }, - )?; - // We found `foo`, have we fully recovered? - self.expect_semi()?; - } - LocalKind::Decl => { - if let Some(colon_sp) = local.colon_sp { - e.span_label( - colon_sp, - format!( - "while parsing the type for {}", - local.pat.descr().map_or_else( - || "the binding".to_string(), - |n| format!("`{n}`") - ) - ), - ); - let suggest_eq = if self.token == token::Dot - && let _ = self.bump() - && let mut snapshot = self.create_snapshot_for_diagnostic() - && let Ok(_) = snapshot - .parse_dot_suffix_expr( - colon_sp, - self.mk_expr_err( - colon_sp, - self.dcx() - .delayed_bug("error during `:` -> `=` recovery"), - ), - ) - .map_err(Diag::cancel) - { - true - } else if let Some(op) = self.check_assoc_op() - && op.node.can_continue_expr_unambiguously() - { - true - } else { - false - }; - if suggest_eq { - e.span_suggestion_short( + StmtKind::Let(local) => { + if self.try_recover_let_missing_semi(local).is_some() { + return Ok(Some(stmt)); + } + if let Err(mut e) = self.expect_semi() { + // We might be at the `,` in `let x = foo;`. Try to recover. + match &mut local.kind { + LocalKind::Init(expr) | LocalKind::InitElse(expr, _) => { + self.check_mistyped_turbofish_with_multiple_type_params(e, expr) + .map_err(|mut e| { + self.recover_missing_dot(&mut e); + self.recover_missing_let_else(&mut e, &local.pat, stmt.span); + e + })?; + // We found `foo`, have we fully recovered? + self.expect_semi()?; + } + LocalKind::Decl => { + if let Some(colon_sp) = local.colon_sp { + e.span_label( colon_sp, - "use `=` if you meant to assign", - "=", - Applicability::MaybeIncorrect, + format!( + "while parsing the type for {}", + local.pat.descr().map_or_else( + || "the binding".to_string(), + |n| format!("`{n}`") + ) + ), ); + let suggest_eq = if self.token == token::Dot + && let _ = self.bump() + && let mut snapshot = self.create_snapshot_for_diagnostic() + && let Ok(_) = snapshot + .parse_dot_suffix_expr( + colon_sp, + self.mk_expr_err( + colon_sp, + self.dcx().delayed_bug( + "error during `:` -> `=` recovery", + ), + ), + ) + .map_err(Diag::cancel) + { + true + } else if let Some(op) = self.check_assoc_op() + && op.node.can_continue_expr_unambiguously() + { + true + } else { + false + }; + if suggest_eq { + e.span_suggestion_short( + colon_sp, + "use `=` if you meant to assign", + "=", + Applicability::MaybeIncorrect, + ); + } } + return Err(e); } - return Err(e); } } eat_semi = false; } - StmtKind::Empty | StmtKind::Item(_) | StmtKind::Let(_) | StmtKind::Semi(_) => { - eat_semi = false - } + StmtKind::Empty | StmtKind::Item(_) | StmtKind::Semi(_) => eat_semi = false, } if add_semi_to_stmt || (eat_semi && self.eat(exp!(Semi))) { diff --git a/tests/ui/issues/const-recover-semi-issue-151149.stderr b/tests/ui/issues/const-recover-semi-issue-151149.stderr deleted file mode 100644 index 96c62c39fb6ad..0000000000000 --- a/tests/ui/issues/const-recover-semi-issue-151149.stderr +++ /dev/null @@ -1,52 +0,0 @@ -error: expected `;`, found `}` - --> $DIR/const-recover-semi-issue-151149.rs:16:38 - | -LL | const C: u8 = u8::const_default() - | ^ help: add `;` here -LL | &C -LL | } - | - unexpected token - -error: expected `;`, found `}` - --> $DIR/const-recover-semi-issue-151149.rs:22:9 - | -LL | + 2 - | ^ help: add `;` here -LL | } - | - unexpected token - -error: expected `;`, found `}` - --> $DIR/const-recover-semi-issue-151149.rs:27:13 - | -LL | + val() - | ^ help: add `;` here -LL | } - | - unexpected token - -error[E0308]: mismatched types - --> $DIR/const-recover-semi-issue-151149.rs:15:19 - | -LL | const fn foo() -> &'static u8 { - | --- ^^^^^^^^^^^ expected `&u8`, found `()` - | | - | implicitly returns `()` as its body has no tail or `return` expression - -error[E0308]: mismatched types - --> $DIR/const-recover-semi-issue-151149.rs:20:19 - | -LL | const fn bar() -> u8 { - | --- ^^ expected `u8`, found `()` - | | - | implicitly returns `()` as its body has no tail or `return` expression - -error[E0308]: mismatched types - --> $DIR/const-recover-semi-issue-151149.rs:25:19 - | -LL | const fn baz() -> u8 { - | --- ^^ expected `u8`, found `()` - | | - | implicitly returns `()` as its body has no tail or `return` expression - -error: aborting due to 6 previous errors - -For more information about this error, try `rustc --explain E0308`. diff --git a/tests/ui/issues/const-recover-semi-issue-151149.rs b/tests/ui/parser/const-recover-semi-issue-151149.rs similarity index 67% rename from tests/ui/issues/const-recover-semi-issue-151149.rs rename to tests/ui/parser/const-recover-semi-issue-151149.rs index f5dc27bb3dd86..b4a45e83613ec 100644 --- a/tests/ui/issues/const-recover-semi-issue-151149.rs +++ b/tests/ui/parser/const-recover-semi-issue-151149.rs @@ -12,6 +12,9 @@ const fn val() -> u8 { 42 } +const C: u8 = u8::const_default() +&1 //~ ERROR expected `;`, found keyword `const` + const fn foo() -> &'static u8 { //~ ERROR mismatched types const C: u8 = u8::const_default() //~ ERROR expected `;` &C @@ -19,12 +22,17 @@ const fn foo() -> &'static u8 { //~ ERROR mismatched types const fn bar() -> u8 { //~ ERROR mismatched types const C: u8 = 1 - + 2 //~ ERROR expected `;` + + 2 //~ ERROR expected `;`, found `}` } const fn baz() -> u8 { //~ ERROR mismatched types const C: u8 = 1 - + val() //~ ERROR expected `;` + + val() //~ ERROR expected `;`, found `}` +} + +fn buzz() { + let r = 1 //~ ERROR expected `;` + &r } fn main() {} diff --git a/tests/ui/parser/const-recover-semi-issue-151149.stderr b/tests/ui/parser/const-recover-semi-issue-151149.stderr new file mode 100644 index 0000000000000..04107ffd2a78d --- /dev/null +++ b/tests/ui/parser/const-recover-semi-issue-151149.stderr @@ -0,0 +1,100 @@ +error: expected `;`, found keyword `const` + --> $DIR/const-recover-semi-issue-151149.rs:16:3 + | +LL | &1 + | ^ help: add `;` here +LL | +LL | const fn foo() -> &'static u8 { + | ----- unexpected token + +error: expected `;`, found `}` + --> $DIR/const-recover-semi-issue-151149.rs:19:38 + | +LL | const C: u8 = u8::const_default() + | ______________________________________^ +LL | | &C + | |______- to finish parsing this const, expected this to be followed by a `;` +LL | } + | - unexpected token + | +note: the const was parsed as having a bit-and binary expression + --> $DIR/const-recover-semi-issue-151149.rs:19:19 + | +LL | const C: u8 = u8::const_default() + | ------------------- parsed as the left-hand expression +LL | &C + | -- parsed as the right-hand expression + | | + | this was parsed as a bit-and +help: you may have meant to write a `;` to terminate the const earlier + | +LL | const C: u8 = u8::const_default(); + | + + +error: expected `;`, found `}` + --> $DIR/const-recover-semi-issue-151149.rs:25:9 + | +LL | + 2 + | ^ help: add `;` here +LL | } + | - unexpected token + +error: expected `;`, found `}` + --> $DIR/const-recover-semi-issue-151149.rs:30:13 + | +LL | + val() + | ^ help: add `;` here +LL | } + | - unexpected token + +error: expected `;`, found `}` + --> $DIR/const-recover-semi-issue-151149.rs:34:14 + | +LL | let r = 1 + | ______________^ +LL | | &r + | |______- to finish parsing this `let` binding, expected this to be followed by a `;` +LL | } + | - unexpected token + | +note: the `let` binding was parsed as having a bit-and binary expression + --> $DIR/const-recover-semi-issue-151149.rs:34:13 + | +LL | let r = 1 + | - parsed as the left-hand expression +LL | &r + | -- parsed as the right-hand expression + | | + | this was parsed as a bit-and +help: you may have meant to write a `;` to terminate the `let` binding earlier + | +LL | let r = 1; + | + + +error[E0308]: mismatched types + --> $DIR/const-recover-semi-issue-151149.rs:18:19 + | +LL | const fn foo() -> &'static u8 { + | --- ^^^^^^^^^^^ expected `&u8`, found `()` + | | + | implicitly returns `()` as its body has no tail or `return` expression + +error[E0308]: mismatched types + --> $DIR/const-recover-semi-issue-151149.rs:23:19 + | +LL | const fn bar() -> u8 { + | --- ^^ expected `u8`, found `()` + | | + | implicitly returns `()` as its body has no tail or `return` expression + +error[E0308]: mismatched types + --> $DIR/const-recover-semi-issue-151149.rs:28:19 + | +LL | const fn baz() -> u8 { + | --- ^^ expected `u8`, found `()` + | | + | implicitly returns `()` as its body has no tail or `return` expression + +error: aborting due to 8 previous errors + +For more information about this error, try `rustc --explain E0308`. From 471b92937253ea0abfb9ec1c977ca0cab402d563 Mon Sep 17 00:00:00 2001 From: yukang Date: Mon, 19 Jan 2026 15:43:03 +0800 Subject: [PATCH 3/3] remove mismatched errors when recovered --- compiler/rustc_parse/src/parser/item.rs | 15 ++++++++++++--- compiler/rustc_parse/src/parser/mod.rs | 3 +++ compiler/rustc_parse/src/parser/stmt.rs | 2 +- .../ui/parser/const-recover-semi-issue-151149.rs | 4 ++-- .../parser/const-recover-semi-issue-151149.stderr | 10 +--------- 5 files changed, 19 insertions(+), 15 deletions(-) diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs index 0c29f56e2bb43..bf40809b07d91 100644 --- a/compiler/rustc_parse/src/parser/item.rs +++ b/compiler/rustc_parse/src/parser/item.rs @@ -2655,9 +2655,17 @@ impl<'a> Parser<'a> { } else if self.check(exp!(OpenBrace)) || self.token.is_metavar_block() { let prev_in_fn_body = self.in_fn_body; self.in_fn_body = true; - let res = self - .parse_block_common(self.token.span, BlockCheckMode::Default, None) - .map(|(attrs, body)| (attrs, Some(body))); + let res = self.parse_block_common(self.token.span, BlockCheckMode::Default, None).map( + |(attrs, mut body)| { + if let Some(guar) = self.fn_body_missing_semi_guar.take() { + body.stmts.push(self.mk_stmt( + body.span, + StmtKind::Expr(self.mk_expr(body.span, ExprKind::Err(guar))), + )); + } + (attrs, Some(body)) + }, + ); self.in_fn_body = prev_in_fn_body; res? } else if self.token == token::Eq { @@ -3434,6 +3442,7 @@ impl<'a> Parser<'a> { return None; } if let Some((span, guar)) = self.missing_semi_from_binop("const", rhs) { + self.fn_body_missing_semi_guar = Some(guar); Some(self.mk_expr(span, ExprKind::Err(guar))) } else { None diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs index 52ab956ddcc9a..0cc6857cdba93 100644 --- a/compiler/rustc_parse/src/parser/mod.rs +++ b/compiler/rustc_parse/src/parser/mod.rs @@ -226,6 +226,8 @@ pub struct Parser<'a> { recovery: Recovery, /// Whether we're parsing a function body. in_fn_body: bool, + /// Whether we have detected a missing semicolon in the function body. + pub fn_body_missing_semi_guar: Option, } // This type is used a lot, e.g. it's cloned when matching many declarative macro rules with @@ -376,6 +378,7 @@ impl<'a> Parser<'a> { current_closure: None, recovery: Recovery::Allowed, in_fn_body: false, + fn_body_missing_semi_guar: None, }; // Make parser point to the first token. diff --git a/compiler/rustc_parse/src/parser/stmt.rs b/compiler/rustc_parse/src/parser/stmt.rs index 8d0de66aabf8d..aeac0d03470c4 100644 --- a/compiler/rustc_parse/src/parser/stmt.rs +++ b/compiler/rustc_parse/src/parser/stmt.rs @@ -929,10 +929,10 @@ impl<'a> Parser<'a> { LocalKind::Decl => return None, }; if let Some((span, guar)) = self.missing_semi_from_binop("`let` binding", expr) { + self.fn_body_missing_semi_guar = Some(guar); *expr = self.mk_expr(span, ExprKind::Err(guar)); return Some(guar); } - None } diff --git a/tests/ui/parser/const-recover-semi-issue-151149.rs b/tests/ui/parser/const-recover-semi-issue-151149.rs index b4a45e83613ec..2b443d7b4609f 100644 --- a/tests/ui/parser/const-recover-semi-issue-151149.rs +++ b/tests/ui/parser/const-recover-semi-issue-151149.rs @@ -15,7 +15,7 @@ const fn val() -> u8 { const C: u8 = u8::const_default() &1 //~ ERROR expected `;`, found keyword `const` -const fn foo() -> &'static u8 { //~ ERROR mismatched types +const fn foo() -> &'static u8 { const C: u8 = u8::const_default() //~ ERROR expected `;` &C } @@ -30,7 +30,7 @@ const fn baz() -> u8 { //~ ERROR mismatched types + val() //~ ERROR expected `;`, found `}` } -fn buzz() { +fn buzz() -> &'static u8 { let r = 1 //~ ERROR expected `;` &r } diff --git a/tests/ui/parser/const-recover-semi-issue-151149.stderr b/tests/ui/parser/const-recover-semi-issue-151149.stderr index 04107ffd2a78d..264306fcba6f3 100644 --- a/tests/ui/parser/const-recover-semi-issue-151149.stderr +++ b/tests/ui/parser/const-recover-semi-issue-151149.stderr @@ -71,14 +71,6 @@ help: you may have meant to write a `;` to terminate the `let` binding earlier LL | let r = 1; | + -error[E0308]: mismatched types - --> $DIR/const-recover-semi-issue-151149.rs:18:19 - | -LL | const fn foo() -> &'static u8 { - | --- ^^^^^^^^^^^ expected `&u8`, found `()` - | | - | implicitly returns `()` as its body has no tail or `return` expression - error[E0308]: mismatched types --> $DIR/const-recover-semi-issue-151149.rs:23:19 | @@ -95,6 +87,6 @@ LL | const fn baz() -> u8 { | | | implicitly returns `()` as its body has no tail or `return` expression -error: aborting due to 8 previous errors +error: aborting due to 7 previous errors For more information about this error, try `rustc --explain E0308`.