diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs index 641121597848c..56facbb70e64f 100644 --- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs +++ b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs @@ -545,8 +545,6 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> { } // for dbg!(x) which may take ownership, suggest dbg!(&x) instead - // but here we actually do not check whether the macro name is `dbg!` - // so that we may extend the scope a bit larger to cover more cases fn suggest_ref_for_dbg_args( &self, body: &hir::Expr<'_>, @@ -560,29 +558,41 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> { }); let Some(var_info) = var_info else { return }; let arg_name = var_info.name; - struct MatchArgFinder { - expr_span: Span, - match_arg_span: Option, + struct MatchArgFinder<'tcx> { + tcx: TyCtxt<'tcx>, + move_span: Span, arg_name: Symbol, + match_arg_span: Option = None, } - impl Visitor<'_> for MatchArgFinder { + impl Visitor<'_> for MatchArgFinder<'_> { fn visit_expr(&mut self, e: &hir::Expr<'_>) { // dbg! is expanded into a match pattern, we need to find the right argument span - if let hir::ExprKind::Match(expr, ..) = &e.kind - && let hir::ExprKind::Path(hir::QPath::Resolved( - _, - path @ Path { segments: [seg], .. }, - )) = &expr.kind - && seg.ident.name == self.arg_name - && self.expr_span.source_callsite().contains(expr.span) + if let hir::ExprKind::Match(scrutinee, ..) = &e.kind + && let hir::ExprKind::Tup(args) = scrutinee.kind + && e.span.macro_backtrace().any(|expn| { + expn.macro_def_id.is_some_and(|macro_def_id| { + self.tcx.is_diagnostic_item(sym::dbg_macro, macro_def_id) + }) + }) { - self.match_arg_span = Some(path.span); + for arg in args { + if let hir::ExprKind::Path(hir::QPath::Resolved( + _, + path @ Path { segments: [seg], .. }, + )) = &arg.kind + && seg.ident.name == self.arg_name + && self.move_span.source_equal(arg.span) + { + self.match_arg_span = Some(path.span); + return; + } + } } hir::intravisit::walk_expr(self, e); } } - let mut finder = MatchArgFinder { expr_span: move_span, match_arg_span: None, arg_name }; + let mut finder = MatchArgFinder { tcx: self.infcx.tcx, move_span, arg_name, .. }; finder.visit_expr(body); if let Some(macro_arg_span) = finder.match_arg_span { err.span_suggestion_verbose( diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs index 286fea7d90505..e6658fc0eec1c 100644 --- a/compiler/rustc_span/src/symbol.rs +++ b/compiler/rustc_span/src/symbol.rs @@ -746,6 +746,7 @@ symbols! { custom_mir, custom_test_frameworks, d32, + dbg_macro, dead_code, dealloc, debug, diff --git a/library/std/src/macros.rs b/library/std/src/macros.rs index 0bb14552432d5..5f9b383c2da37 100644 --- a/library/std/src/macros.rs +++ b/library/std/src/macros.rs @@ -5,6 +5,9 @@ //! library. // ignore-tidy-dbg +#[cfg(test)] +mod tests; + #[doc = include_str!("../../core/src/macros/panic.md")] #[macro_export] #[rustc_builtin_macro(std_panic)] @@ -359,19 +362,16 @@ macro_rules! dbg { }; } -/// Internal macro that processes a list of expressions and produces a chain of -/// nested `match`es, one for each expression, before finally calling `eprint!` -/// with the collected information and returning all the evaluated expressions -/// in a tuple. +/// Internal macro that processes a list of expressions, binds their results +/// with `match`, calls `eprint!` with the collected information, and returns +/// all the evaluated expressions in a tuple. /// /// E.g. `dbg_internal!(() () (1, 2))` expands into /// ```rust, ignore -/// match 1 { -/// tmp_1 => match 2 { -/// tmp_2 => { -/// eprint!("...", &tmp_1, &tmp_2, /* some other arguments */); -/// (tmp_1, tmp_2) -/// } +/// match (1, 2) { +/// (tmp_1, tmp_2) => { +/// eprint!("...", &tmp_1, &tmp_2, /* some other arguments */); +/// (tmp_1, tmp_2) /// } /// } /// ``` @@ -380,37 +380,41 @@ macro_rules! dbg { #[doc(hidden)] #[rustc_macro_transparency = "semiopaque"] pub macro dbg_internal { - (($($piece:literal),+) ($($processed:expr => $bound:expr),+) ()) => {{ - $crate::eprint!( - $crate::concat!($($piece),+), - $( - $crate::stringify!($processed), - // The `&T: Debug` check happens here (not in the format literal desugaring) - // to avoid format literal related messages and suggestions. - &&$bound as &dyn $crate::fmt::Debug - ),+, - // The location returned here is that of the macro invocation, so - // it will be the same for all expressions. Thus, label these - // arguments so that they can be reused in every piece of the - // formatting template. - file=$crate::file!(), - line=$crate::line!(), - column=$crate::column!() - ); - // Comma separate the variables only when necessary so that this will - // not yield a tuple for a single expression, but rather just parenthesize - // the expression. - ($($bound),+) - }}, - (($($piece:literal),*) ($($processed:expr => $bound:expr),*) ($val:expr $(,$rest:expr)*)) => { + (($($piece:literal),+) ($($processed:expr => $bound:ident),+) ()) => { // Use of `match` here is intentional because it affects the lifetimes // of temporaries - https://stackoverflow.com/a/48732525/1063961 - match $val { - tmp => $crate::macros::dbg_internal!( - ($($piece,)* "[{file}:{line}:{column}] {} = {:#?}\n") - ($($processed => $bound,)* $val => tmp) - ($($rest),*) - ), + // Always put the arguments in a tuple to avoid an unused parens lint on the pattern. + match ($($processed,)+) { + ($($bound,)+) => { + $crate::eprint!( + $crate::concat!($($piece),+), + $( + $crate::stringify!($processed), + // The `&T: Debug` check happens here (not in the format literal desugaring) + // to avoid format literal related messages and suggestions. + &&$bound as &dyn $crate::fmt::Debug + ),+, + // The location returned here is that of the macro invocation, so + // it will be the same for all expressions. Thus, label these + // arguments so that they can be reused in every piece of the + // formatting template. + file=$crate::file!(), + line=$crate::line!(), + column=$crate::column!() + ); + // Comma separate the variables only when necessary so that this will + // not yield a tuple for a single expression, but rather just parenthesize + // the expression. + ($($bound),+) + + } } }, + (($($piece:literal),*) ($($processed:expr => $bound:ident),*) ($val:expr $(,$rest:expr)*)) => { + $crate::macros::dbg_internal!( + ($($piece,)* "[{file}:{line}:{column}] {} = {:#?}\n") + ($($processed => $bound,)* $val => tmp) + ($($rest),*) + ) + }, } diff --git a/library/std/src/macros/tests.rs b/library/std/src/macros/tests.rs new file mode 100644 index 0000000000000..db2be925ff30a --- /dev/null +++ b/library/std/src/macros/tests.rs @@ -0,0 +1,13 @@ +// ignore-tidy-dbg + +/// Test for : +/// `dbg!` shouldn't drop arguments' temporaries. +#[test] +fn no_dropping_temps() { + fn temp() {} + + *dbg!(&temp()); + *dbg!(&temp(), 1).0; + *dbg!(0, &temp()).1; + *dbg!(0, &temp(), 2).1; +} diff --git a/src/tools/clippy/clippy_lints/src/dbg_macro.rs b/src/tools/clippy/clippy_lints/src/dbg_macro.rs index eb14ef18c03da..63968a8b5e04e 100644 --- a/src/tools/clippy/clippy_lints/src/dbg_macro.rs +++ b/src/tools/clippy/clippy_lints/src/dbg_macro.rs @@ -5,7 +5,7 @@ use clippy_utils::source::snippet_with_applicability; use clippy_utils::{is_in_test, sym}; use rustc_data_structures::fx::FxHashSet; use rustc_errors::Applicability; -use rustc_hir::{Arm, Closure, ClosureKind, CoroutineKind, Expr, ExprKind, LetStmt, LocalSource, Node, Stmt, StmtKind}; +use rustc_hir::{Closure, ClosureKind, CoroutineKind, Expr, ExprKind, LetStmt, LocalSource, Node, Stmt, StmtKind}; use rustc_lint::{LateContext, LateLintPass, LintContext}; use rustc_session::impl_lint_pass; use rustc_span::{Span, SyntaxContext}; @@ -92,16 +92,15 @@ impl LateLintPass<'_> for DbgMacro { (macro_call.span, String::from("()")) } }, - ExprKind::Match(first, arms, _) => { - let vals = collect_vals(first, arms); - let suggestion = match *vals.as_slice() { + ExprKind::Match(args, _, _) => { + let suggestion = match args.kind { // dbg!(1) => 1 - [val] => { + ExprKind::Tup([val]) => { snippet_with_applicability(cx, val.span.source_callsite(), "..", &mut applicability) .to_string() }, // dbg!(2, 3) => (2, 3) - [first, .., last] => { + ExprKind::Tup([first, .., last]) => { let snippet = snippet_with_applicability( cx, first.span.source_callsite().to(last.span.source_callsite()), @@ -165,39 +164,3 @@ fn is_async_move_desugar<'tcx>(expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx fn first_dbg_macro_in_expansion(cx: &LateContext<'_>, span: Span) -> Option { macro_backtrace(span).find(|mc| cx.tcx.is_diagnostic_item(sym::dbg_macro, mc.def_id)) } - -/// Extracts all value expressions from the `match`-tree generated by `dbg!`. -/// -/// E.g. from -/// ```rust, ignore -/// match 1 { -/// tmp_1 => match 2 { -/// tmp_2 => { -/// /* printing */ -/// (tmp_1, tmp_2) -/// } -/// } -/// } -/// ``` -/// this extracts `1` and `2`. -fn collect_vals<'hir>(first: &'hir Expr<'hir>, mut arms: &'hir [Arm<'hir>]) -> Vec<&'hir Expr<'hir>> { - let mut vals = vec![first]; - loop { - let [arm] = arms else { - unreachable!("dbg! macro expansion only has single-arm matches") - }; - - match is_async_move_desugar(arm.body) - .unwrap_or(arm.body) - .peel_drop_temps() - .kind - { - ExprKind::Block(..) => return vals, - ExprKind::Match(val, a, _) => { - vals.push(val); - arms = a; - }, - _ => unreachable!("dbg! macro expansion only results in block or match expressions"), - } - } -} diff --git a/src/tools/clippy/clippy_utils/src/sym.rs b/src/tools/clippy/clippy_utils/src/sym.rs index d6ba678434bc7..909dc3956d5f7 100644 --- a/src/tools/clippy/clippy_utils/src/sym.rs +++ b/src/tools/clippy/clippy_utils/src/sym.rs @@ -199,7 +199,6 @@ generate! { cx, cycle, cyclomatic_complexity, - dbg_macro, de, debug_struct, deprecated_in_future, diff --git a/src/tools/miri/tests/fail/dangling_pointers/dangling_primitive.stderr b/src/tools/miri/tests/fail/dangling_pointers/dangling_primitive.stderr index afc2cb214842e..4f06a1afa50fe 100644 --- a/src/tools/miri/tests/fail/dangling_pointers/dangling_primitive.stderr +++ b/src/tools/miri/tests/fail/dangling_pointers/dangling_primitive.stderr @@ -2,7 +2,7 @@ error: Undefined Behavior: memory access failed: ALLOC has been freed, so this p --> tests/fail/dangling_pointers/dangling_primitive.rs:LL:CC | LL | dbg!(*ptr); - | ^^^^^^^^^^ Undefined Behavior occurred here + | ^^^^ Undefined Behavior occurred here | = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information diff --git a/src/tools/miri/tests/fail/function_calls/return_pointer_on_unwind.stderr b/src/tools/miri/tests/fail/function_calls/return_pointer_on_unwind.stderr index 364a4b4a74418..88d5694c4736d 100644 --- a/src/tools/miri/tests/fail/function_calls/return_pointer_on_unwind.stderr +++ b/src/tools/miri/tests/fail/function_calls/return_pointer_on_unwind.stderr @@ -7,7 +7,7 @@ error: Undefined Behavior: reading memory at ALLOC[0x0..0x4], but memory is unin --> tests/fail/function_calls/return_pointer_on_unwind.rs:LL:CC | LL | dbg!(x.0); - | ^^^^^^^^^ Undefined Behavior occurred here + | ^^^ Undefined Behavior occurred here | = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information diff --git a/tests/ui/borrowck/dbg-issue-120327.rs b/tests/ui/borrowck/dbg-issue-120327.rs index 2de43f634877a..45605acc34334 100644 --- a/tests/ui/borrowck/dbg-issue-120327.rs +++ b/tests/ui/borrowck/dbg-issue-120327.rs @@ -1,67 +1,44 @@ +//! Diagnostic test for : suggest borrowing +//! variables passed to `dbg!` that are later used. +//@ dont-require-annotations: HELP + fn s() -> String { let a = String::new(); - dbg!(a); + dbg!(a); //~ HELP consider borrowing instead of transferring ownership return a; //~ ERROR use of moved value: } fn m() -> String { let a = String::new(); - dbg!(1, 2, a, 1, 2); + dbg!(1, 2, a, 1, 2); //~ HELP consider borrowing instead of transferring ownership return a; //~ ERROR use of moved value: } fn t(a: String) -> String { let b: String = "".to_string(); - dbg!(a, b); + dbg!(a, b); //~ HELP consider borrowing instead of transferring ownership return b; //~ ERROR use of moved value: } fn x(a: String) -> String { let b: String = "".to_string(); - dbg!(a, b); + dbg!(a, b); //~ HELP consider borrowing instead of transferring ownership return a; //~ ERROR use of moved value: } -macro_rules! my_dbg { - () => { - eprintln!("[{}:{}:{}]", file!(), line!(), column!()) - }; - ($val:expr $(,)?) => { - match $val { - tmp => { - eprintln!("[{}:{}:{}] {} = {:#?}", - file!(), line!(), column!(), stringify!($val), &tmp); - tmp - } - } - }; - ($($val:expr),+ $(,)?) => { - ($(my_dbg!($val)),+,) - }; -} - -fn test_my_dbg() -> String { - let b: String = "".to_string(); - my_dbg!(b, 1); - return b; //~ ERROR use of moved value: -} - -fn test_not_macro() -> String { - let a = String::new(); - let _b = match a { - tmp => { - eprintln!("dbg: {}", tmp); - tmp - } - }; - return a; //~ ERROR use of moved value: +fn two_of_them(a: String) -> String { + dbg!(a, a); //~ ERROR use of moved value + //~| HELP consider borrowing instead of transferring ownership + //~| HELP consider borrowing instead of transferring ownership + return a; //~ ERROR use of moved value } fn get_expr(_s: String) {} +// The suggestion is purely syntactic; applying it here will result in a type error. fn test() { let a: String = "".to_string(); - let _res = get_expr(dbg!(a)); + let _res = get_expr(dbg!(a)); //~ HELP consider borrowing instead of transferring ownership let _l = a.len(); //~ ERROR borrow of moved value } diff --git a/tests/ui/borrowck/dbg-issue-120327.stderr b/tests/ui/borrowck/dbg-issue-120327.stderr index efacc0c3f1341..e7a7151e541dd 100644 --- a/tests/ui/borrowck/dbg-issue-120327.stderr +++ b/tests/ui/borrowck/dbg-issue-120327.stderr @@ -1,112 +1,133 @@ error[E0382]: use of moved value: `a` - --> $DIR/dbg-issue-120327.rs:4:12 + --> $DIR/dbg-issue-120327.rs:8:12 | LL | let a = String::new(); | - move occurs because `a` has type `String`, which does not implement the `Copy` trait LL | dbg!(a); - | ------- value moved here + | - value moved here LL | return a; | ^ value used here after move | +help: consider cloning the value if the performance cost is acceptable + | +LL | dbg!(a.clone()); + | ++++++++ help: consider borrowing instead of transferring ownership | LL | dbg!(&a); | + error[E0382]: use of moved value: `a` - --> $DIR/dbg-issue-120327.rs:10:12 + --> $DIR/dbg-issue-120327.rs:14:12 | LL | let a = String::new(); | - move occurs because `a` has type `String`, which does not implement the `Copy` trait LL | dbg!(1, 2, a, 1, 2); - | ------------------- value moved here + | - value moved here LL | return a; | ^ value used here after move | +help: consider cloning the value if the performance cost is acceptable + | +LL | dbg!(1, 2, a.clone(), 1, 2); + | ++++++++ help: consider borrowing instead of transferring ownership | LL | dbg!(1, 2, &a, 1, 2); | + error[E0382]: use of moved value: `b` - --> $DIR/dbg-issue-120327.rs:16:12 + --> $DIR/dbg-issue-120327.rs:20:12 | LL | let b: String = "".to_string(); | - move occurs because `b` has type `String`, which does not implement the `Copy` trait LL | dbg!(a, b); - | ---------- value moved here + | - value moved here LL | return b; | ^ value used here after move | +help: consider cloning the value if the performance cost is acceptable + | +LL | dbg!(a, b.clone()); + | ++++++++ help: consider borrowing instead of transferring ownership | LL | dbg!(a, &b); | + error[E0382]: use of moved value: `a` - --> $DIR/dbg-issue-120327.rs:22:12 + --> $DIR/dbg-issue-120327.rs:26:12 | LL | fn x(a: String) -> String { | - move occurs because `a` has type `String`, which does not implement the `Copy` trait LL | let b: String = "".to_string(); LL | dbg!(a, b); - | ---------- value moved here + | - value moved here LL | return a; | ^ value used here after move | +help: consider cloning the value if the performance cost is acceptable + | +LL | dbg!(a.clone(), b); + | ++++++++ help: consider borrowing instead of transferring ownership | LL | dbg!(&a, b); | + -error[E0382]: use of moved value: `b` - --> $DIR/dbg-issue-120327.rs:46:12 +error[E0382]: use of moved value: `a` + --> $DIR/dbg-issue-120327.rs:30:13 | -LL | tmp => { - | --- value moved here -... -LL | let b: String = "".to_string(); - | - move occurs because `b` has type `String`, which does not implement the `Copy` trait -LL | my_dbg!(b, 1); -LL | return b; - | ^ value used here after move +LL | fn two_of_them(a: String) -> String { + | - move occurs because `a` has type `String`, which does not implement the `Copy` trait +LL | dbg!(a, a); + | - ^ value used here after move + | | + | value moved here | -help: consider borrowing instead of transferring ownership +help: consider cloning the value if the performance cost is acceptable | -LL | my_dbg!(&b, 1); - | + -help: borrow this binding in the pattern to avoid moving the value +LL | dbg!(a.clone(), a); + | ++++++++ +help: consider borrowing instead of transferring ownership | -LL | ref tmp => { - | +++ +LL | dbg!(&a, a); + | + error[E0382]: use of moved value: `a` - --> $DIR/dbg-issue-120327.rs:57:12 + --> $DIR/dbg-issue-120327.rs:33:12 | -LL | let a = String::new(); - | - move occurs because `a` has type `String`, which does not implement the `Copy` trait -LL | let _b = match a { -LL | tmp => { - | --- value moved here +LL | fn two_of_them(a: String) -> String { + | - move occurs because `a` has type `String`, which does not implement the `Copy` trait +LL | dbg!(a, a); + | - value moved here ... LL | return a; | ^ value used here after move | -help: borrow this binding in the pattern to avoid moving the value +help: consider cloning the value if the performance cost is acceptable + | +LL | dbg!(a, a.clone()); + | ++++++++ +help: consider borrowing instead of transferring ownership | -LL | ref tmp => { - | +++ +LL | dbg!(a, &a); + | + error[E0382]: borrow of moved value: `a` - --> $DIR/dbg-issue-120327.rs:65:14 + --> $DIR/dbg-issue-120327.rs:42:14 | LL | let a: String = "".to_string(); | - move occurs because `a` has type `String`, which does not implement the `Copy` trait LL | let _res = get_expr(dbg!(a)); - | ------- value moved here + | - value moved here LL | let _l = a.len(); | ^ value borrowed here after move | +help: consider cloning the value if the performance cost is acceptable + | +LL | let _res = get_expr(dbg!(a.clone())); + | ++++++++ help: consider borrowing instead of transferring ownership | LL | let _res = get_expr(dbg!(&a)); diff --git a/tests/ui/liveness/liveness-upvars.rs b/tests/ui/liveness/liveness-upvars.rs index be58b48a40576..0e198f1dea10b 100644 --- a/tests/ui/liveness/liveness-upvars.rs +++ b/tests/ui/liveness/liveness-upvars.rs @@ -98,7 +98,7 @@ pub fn g(mut v: T) { } pub fn h() { - let mut z = T::default(); + let mut z = T::default(); //~ WARN unused variable: `z` let _ = move |b| { loop { if b { diff --git a/tests/ui/liveness/liveness-upvars.stderr b/tests/ui/liveness/liveness-upvars.stderr index cfed2830164ad..0bb5786ab3e2e 100644 --- a/tests/ui/liveness/liveness-upvars.stderr +++ b/tests/ui/liveness/liveness-upvars.stderr @@ -156,6 +156,14 @@ LL | z = T::default(); | = help: maybe it is overwritten before being read? +warning: unused variable: `z` + --> $DIR/liveness-upvars.rs:101:9 + | +LL | let mut z = T::default(); + | ^^^^^ help: if this is intentional, prefix it with an underscore: `_z` + | + = note: `#[warn(unused_variables)]` implied by `#[warn(unused)]` + warning: value captured by `state` is never read --> $DIR/liveness-upvars.rs:131:9 | @@ -196,5 +204,5 @@ LL | s = yield (); | = help: maybe it is overwritten before being read? -warning: 24 warnings emitted +warning: 25 warnings emitted diff --git a/tests/ui/rfcs/rfc-2361-dbg-macro/dbg-macro-move-semantics.stderr b/tests/ui/rfcs/rfc-2361-dbg-macro/dbg-macro-move-semantics.stderr index f8ef315b9cc78..7ce5ebf81e310 100644 --- a/tests/ui/rfcs/rfc-2361-dbg-macro/dbg-macro-move-semantics.stderr +++ b/tests/ui/rfcs/rfc-2361-dbg-macro/dbg-macro-move-semantics.stderr @@ -1,13 +1,21 @@ error[E0382]: use of moved value: `a` - --> $DIR/dbg-macro-move-semantics.rs:9:13 + --> $DIR/dbg-macro-move-semantics.rs:9:18 | LL | let a = NoCopy(0); | - move occurs because `a` has type `NoCopy`, which does not implement the `Copy` trait LL | let _ = dbg!(a); - | ------- value moved here + | - value moved here LL | let _ = dbg!(a); - | ^^^^^^^ value used here after move + | ^ value used here after move | +note: if `NoCopy` implemented `Clone`, you could clone the value + --> $DIR/dbg-macro-move-semantics.rs:4:1 + | +LL | struct NoCopy(usize); + | ^^^^^^^^^^^^^ consider implementing `Clone` for this type +... +LL | let _ = dbg!(a); + | - you could clone this value help: consider borrowing instead of transferring ownership | LL | let _ = dbg!(&a);