diff --git a/src/librustc_middle/mir/mod.rs b/src/librustc_middle/mir/mod.rs index 70ae2fd8ac9..4a388def5c1 100644 --- a/src/librustc_middle/mir/mod.rs +++ b/src/librustc_middle/mir/mod.rs @@ -625,6 +625,9 @@ pub struct BlockTailInfo { /// Examples include `{ ...; tail };` and `let _ = { ...; tail };` /// but not e.g., `let _x = { ...; tail };` pub tail_result_is_ignored: bool, + + /// `Span` of the tail expression. + pub span: Span, } /// A MIR local. diff --git a/src/librustc_mir/borrow_check/diagnostics/explain_borrow.rs b/src/librustc_mir/borrow_check/diagnostics/explain_borrow.rs index 7645182ad1f..5253acbba7f 100644 --- a/src/librustc_mir/borrow_check/diagnostics/explain_borrow.rs +++ b/src/librustc_mir/borrow_check/diagnostics/explain_borrow.rs @@ -156,23 +156,32 @@ impl BorrowExplanation { err.span_label(body.source_info(drop_loc).span, message); if let Some(info) = &local_decl.is_block_tail { - // FIXME: use span_suggestion instead, highlighting the - // whole block tail expression. - let msg = if info.tail_result_is_ignored { - "The temporary is part of an expression at the end of a block. \ - Consider adding semicolon after the expression so its temporaries \ - are dropped sooner, before the local variables declared by the \ - block are dropped." + if info.tail_result_is_ignored { + err.span_suggestion_verbose( + info.span.shrink_to_hi(), + "consider adding semicolon after the expression so its \ + temporaries are dropped sooner, before the local variables \ + declared by the block are dropped", + ";".to_string(), + Applicability::MaybeIncorrect, + ); } else { - "The temporary is part of an expression at the end of a block. \ - Consider forcing this temporary to be dropped sooner, before \ - the block's local variables are dropped. \ - For example, you could save the expression's value in a new \ - local variable `x` and then make `x` be the expression \ - at the end of the block." + err.note( + "the temporary is part of an expression at the end of a \ + block;\nconsider forcing this temporary to be dropped sooner, \ + before the block's local variables are dropped", + ); + err.multipart_suggestion( + "for example, you could save the expression's value in a new \ + local variable `x` and then make `x` be the expression at the \ + end of the block", + vec![ + (info.span.shrink_to_lo(), "let x = ".to_string()), + (info.span.shrink_to_hi(), "; x".to_string()), + ], + Applicability::MaybeIncorrect, + ); }; - - err.note(msg); } } } diff --git a/src/librustc_mir_build/build/block.rs b/src/librustc_mir_build/build/block.rs index 3f94fb82890..c2fe41169c1 100644 --- a/src/librustc_mir_build/build/block.rs +++ b/src/librustc_mir_build/build/block.rs @@ -173,7 +173,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { if let Some(expr) = expr { let tail_result_is_ignored = destination_ty.is_unit() || this.block_context.currently_ignores_tail_results(); - this.block_context.push(BlockFrame::TailExpr { tail_result_is_ignored }); + let span = match expr { + ExprRef::Hair(expr) => expr.span, + ExprRef::Mirror(ref expr) => expr.span, + }; + this.block_context.push(BlockFrame::TailExpr { tail_result_is_ignored, span }); unpack!(block = this.into(destination, block, expr)); let popped = this.block_context.pop(); diff --git a/src/librustc_mir_build/build/expr/stmt.rs b/src/librustc_mir_build/build/expr/stmt.rs index 92e1e105185..49d6ce39ddf 100644 --- a/src/librustc_mir_build/build/expr/stmt.rs +++ b/src/librustc_mir_build/build/expr/stmt.rs @@ -151,7 +151,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { } } this.block_context - .push(BlockFrame::TailExpr { tail_result_is_ignored: true }); + .push(BlockFrame::TailExpr { tail_result_is_ignored: true, span: expr.span }); return Some(expr.span); } } diff --git a/src/librustc_mir_build/build/mod.rs b/src/librustc_mir_build/build/mod.rs index ee45ff5a495..7d99a8d61d2 100644 --- a/src/librustc_mir_build/build/mod.rs +++ b/src/librustc_mir_build/build/mod.rs @@ -245,6 +245,9 @@ enum BlockFrame { /// /// Example: `let _ = { STMT_1; EXPR };` tail_result_is_ignored: bool, + + /// `Span` of the tail expression. + span: Span, }, /// Generic mark meaning that the block occurred as a subexpression @@ -372,8 +375,8 @@ impl BlockContext { match bf { BlockFrame::SubExpr => continue, BlockFrame::Statement { .. } => break, - &BlockFrame::TailExpr { tail_result_is_ignored } => { - return Some(BlockTailInfo { tail_result_is_ignored }); + &BlockFrame::TailExpr { tail_result_is_ignored, span } => { + return Some(BlockTailInfo { tail_result_is_ignored, span }); } } } @@ -397,7 +400,7 @@ impl BlockContext { // otherwise: use accumulated is_ignored state. Some( - BlockFrame::TailExpr { tail_result_is_ignored: ignored } + BlockFrame::TailExpr { tail_result_is_ignored: ignored, .. } | BlockFrame::Statement { ignores_expr_result: ignored }, ) => *ignored, } diff --git a/src/test/ui/nll/issue-54382-use-span-of-tail-of-block.stderr b/src/test/ui/nll/issue-54382-use-span-of-tail-of-block.stderr index 8412cbdc54b..2dca92e2be1 100644 --- a/src/test/ui/nll/issue-54382-use-span-of-tail-of-block.stderr +++ b/src/test/ui/nll/issue-54382-use-span-of-tail-of-block.stderr @@ -13,7 +13,10 @@ LL | LL | ; | - ... and the borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `D` | - = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped. +help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped + | +LL | D("other").next(&_thing1); + | ^ error: aborting due to previous error diff --git a/src/test/ui/nll/issue-54556-niconii.stderr b/src/test/ui/nll/issue-54556-niconii.stderr index 40cd04de5ec..b4791fd22b4 100644 --- a/src/test/ui/nll/issue-54556-niconii.stderr +++ b/src/test/ui/nll/issue-54556-niconii.stderr @@ -13,7 +13,10 @@ LL | } | `counter` dropped here while still borrowed | ... and the borrow might be used here, when that temporary is dropped and runs the destructor for type `std::result::Result, ()>` | - = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped. +help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped + | +LL | if let Ok(_) = counter.lock() { }; + | ^ error: aborting due to previous error diff --git a/src/test/ui/nll/issue-54556-stephaneyfx.stderr b/src/test/ui/nll/issue-54556-stephaneyfx.stderr index 0bf76485eef..77065f0b8d2 100644 --- a/src/test/ui/nll/issue-54556-stephaneyfx.stderr +++ b/src/test/ui/nll/issue-54556-stephaneyfx.stderr @@ -12,7 +12,12 @@ LL | } | `stmt` dropped here while still borrowed | ... and the borrow might be used here, when that temporary is dropped and runs the destructor for type `std::iter::Map, [closure@$DIR/issue-54556-stephaneyfx.rs:28:14: 28:23]>` | - = note: The temporary is part of an expression at the end of a block. Consider forcing this temporary to be dropped sooner, before the block's local variables are dropped. For example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block. + = note: the temporary is part of an expression at the end of a block; + consider forcing this temporary to be dropped sooner, before the block's local variables are dropped +help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block + | +LL | let x = rows.map(|row| row).next(); x + | ^^^^^^^ ^^^ error: aborting due to previous error diff --git a/src/test/ui/nll/issue-54556-temps-in-tail-diagnostic.stderr b/src/test/ui/nll/issue-54556-temps-in-tail-diagnostic.stderr index 513dca7950a..047fdbc9148 100644 --- a/src/test/ui/nll/issue-54556-temps-in-tail-diagnostic.stderr +++ b/src/test/ui/nll/issue-54556-temps-in-tail-diagnostic.stderr @@ -12,7 +12,10 @@ LL | LL | ; | - ... and the borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `D` | - = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped. +help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped + | +LL | D(&_thing1).end(); + | ^ error: aborting due to previous error diff --git a/src/test/ui/nll/issue-54556-used-vs-unused-tails.stderr b/src/test/ui/nll/issue-54556-used-vs-unused-tails.stderr index 52d0870b78f..85920a8e739 100644 --- a/src/test/ui/nll/issue-54556-used-vs-unused-tails.stderr +++ b/src/test/ui/nll/issue-54556-used-vs-unused-tails.stderr @@ -8,7 +8,10 @@ LL | { let mut _t1 = D(Box::new("t1")); D(&_t1).end() } ; // | | borrowed value does not live long enough | a temporary with access to the borrow is created here ... | - = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped. +help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped + | +LL | { let mut _t1 = D(Box::new("t1")); D(&_t1).end(); } ; // suggest `;` + | ^ error[E0597]: `_t1` does not live long enough --> $DIR/issue-54556-used-vs-unused-tails.rs:13:55 @@ -20,7 +23,10 @@ LL | { { let mut _t1 = D(Box::new("t1")); D(&_t1).end() } } ; // | | borrowed value does not live long enough | a temporary with access to the borrow is created here ... | - = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped. +help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped + | +LL | { { let mut _t1 = D(Box::new("t1")); D(&_t1).end(); } } ; // suggest `;` + | ^ error[E0597]: `_t1` does not live long enough --> $DIR/issue-54556-used-vs-unused-tails.rs:16:55 @@ -32,7 +38,10 @@ LL | { { let mut _t1 = D(Box::new("t1")); D(&_t1).end() }; } // | | borrowed value does not live long enough | a temporary with access to the borrow is created here ... | - = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped. +help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped + | +LL | { { let mut _t1 = D(Box::new("t1")); D(&_t1).end(); }; } // suggest `;` + | ^ error[E0597]: `_t1` does not live long enough --> $DIR/issue-54556-used-vs-unused-tails.rs:19:55 @@ -44,7 +53,10 @@ LL | let _ = { let mut _t1 = D(Box::new("t1")); D(&_t1).end() } ; // | | borrowed value does not live long enough | a temporary with access to the borrow is created here ... | - = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped. +help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped + | +LL | let _ = { let mut _t1 = D(Box::new("t1")); D(&_t1).end(); } ; // suggest `;` + | ^ error[E0597]: `_t1` does not live long enough --> $DIR/issue-54556-used-vs-unused-tails.rs:22:55 @@ -56,7 +68,10 @@ LL | let _u = { let mut _t1 = D(Box::new("t1")); D(&_t1).unit() } ; // | | borrowed value does not live long enough | a temporary with access to the borrow is created here ... | - = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped. +help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped + | +LL | let _u = { let mut _t1 = D(Box::new("t1")); D(&_t1).unit(); } ; // suggest `;` + | ^ error[E0597]: `_t1` does not live long enough --> $DIR/issue-54556-used-vs-unused-tails.rs:25:55 @@ -68,7 +83,12 @@ LL | let _x = { let mut _t1 = D(Box::new("t1")); D(&_t1).end() } ; // | | borrowed value does not live long enough | a temporary with access to the borrow is created here ... | - = note: The temporary is part of an expression at the end of a block. Consider forcing this temporary to be dropped sooner, before the block's local variables are dropped. For example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block. + = note: the temporary is part of an expression at the end of a block; + consider forcing this temporary to be dropped sooner, before the block's local variables are dropped +help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block + | +LL | let _x = { let mut _t1 = D(Box::new("t1")); let x = D(&_t1).end(); x } ; // `let x = ...; x` + | ^^^^^^^ ^^^ error[E0597]: `_t1` does not live long enough --> $DIR/issue-54556-used-vs-unused-tails.rs:30:55 @@ -80,7 +100,12 @@ LL | _y = { let mut _t1 = D(Box::new("t1")); D(&_t1).end() } ; // `l | | borrowed value does not live long enough | a temporary with access to the borrow is created here ... | - = note: The temporary is part of an expression at the end of a block. Consider forcing this temporary to be dropped sooner, before the block's local variables are dropped. For example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block. + = note: the temporary is part of an expression at the end of a block; + consider forcing this temporary to be dropped sooner, before the block's local variables are dropped +help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block + | +LL | _y = { let mut _t1 = D(Box::new("t1")); let x = D(&_t1).end(); x } ; // `let x = ...; x` + | ^^^^^^^ ^^^ error[E0597]: `_t1` does not live long enough --> $DIR/issue-54556-used-vs-unused-tails.rs:37:55 @@ -93,7 +118,10 @@ LL | fn f_local_ref() { let mut _t1 = D(Box::new("t1")); D(&_t1).unit() } // | | borrowed value does not live long enough | a temporary with access to the borrow is created here ... | - = note: The temporary is part of an expression at the end of a block. Consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped. +help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped + | +LL | fn f_local_ref() { let mut _t1 = D(Box::new("t1")); D(&_t1).unit(); } // suggest `;` + | ^ error[E0597]: `_t1` does not live long enough --> $DIR/issue-54556-used-vs-unused-tails.rs:40:55 @@ -106,7 +134,12 @@ LL | fn f() -> String { let mut _t1 = D(Box::new("t1")); D(&_t1).end() } // | | borrowed value does not live long enough | a temporary with access to the borrow is created here ... | - = note: The temporary is part of an expression at the end of a block. Consider forcing this temporary to be dropped sooner, before the block's local variables are dropped. For example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block. + = note: the temporary is part of an expression at the end of a block; + consider forcing this temporary to be dropped sooner, before the block's local variables are dropped +help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block + | +LL | fn f() -> String { let mut _t1 = D(Box::new("t1")); let x = D(&_t1).end(); x } // `let x = ...; x` + | ^^^^^^^ ^^^ error: aborting due to 9 previous errors diff --git a/src/test/ui/span/destructor-restrictions.stderr b/src/test/ui/span/destructor-restrictions.stderr index a3c6cfb6ae4..b5cd29f99c6 100644 --- a/src/test/ui/span/destructor-restrictions.stderr +++ b/src/test/ui/span/destructor-restrictions.stderr @@ -11,7 +11,12 @@ LL | }; | | | `*a` dropped here while still borrowed | - = note: The temporary is part of an expression at the end of a block. Consider forcing this temporary to be dropped sooner, before the block's local variables are dropped. For example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block. + = note: the temporary is part of an expression at the end of a block; + consider forcing this temporary to be dropped sooner, before the block's local variables are dropped +help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block + | +LL | let x = *a.borrow() + 1; x + | ^^^^^^^ ^^^ error: aborting due to previous error diff --git a/src/test/ui/span/issue-23338-locals-die-before-temps-of-body.stderr b/src/test/ui/span/issue-23338-locals-die-before-temps-of-body.stderr index 46969458145..46702d364a8 100644 --- a/src/test/ui/span/issue-23338-locals-die-before-temps-of-body.stderr +++ b/src/test/ui/span/issue-23338-locals-die-before-temps-of-body.stderr @@ -12,7 +12,12 @@ LL | } | `y` dropped here while still borrowed | ... and the borrow might be used here, when that temporary is dropped and runs the destructor for type `std::cell::Ref<'_, std::string::String>` | - = note: The temporary is part of an expression at the end of a block. Consider forcing this temporary to be dropped sooner, before the block's local variables are dropped. For example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block. + = note: the temporary is part of an expression at the end of a block; + consider forcing this temporary to be dropped sooner, before the block's local variables are dropped +help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block + | +LL | let x = y.borrow().clone(); x + | ^^^^^^^ ^^^ error[E0597]: `y` does not live long enough --> $DIR/issue-23338-locals-die-before-temps-of-body.rs:17:9 @@ -27,7 +32,12 @@ LL | }; | | | `y` dropped here while still borrowed | - = note: The temporary is part of an expression at the end of a block. Consider forcing this temporary to be dropped sooner, before the block's local variables are dropped. For example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block. + = note: the temporary is part of an expression at the end of a block; + consider forcing this temporary to be dropped sooner, before the block's local variables are dropped +help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block + | +LL | let x = y.borrow().clone(); x + | ^^^^^^^ ^^^ error: aborting due to 2 previous errors