Fix range literals borrowing suggestions #54734
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@@ -309,11 +309,20 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> { | |
| }; | ||
| if self.can_coerce(ref_ty, expected) { | ||
| if let Ok(src) = cm.span_to_snippet(sp) { | ||
| let needs_parens = match expr.node { | ||
| // parenthesize if needed (Issue #46756) | ||
| hir::ExprKind::Cast(_, _) | | ||
| hir::ExprKind::Binary(_, _, _) => true, | ||
| // parenthesize borrows of range literals (Issue #54505) | ||
| _ if self.is_range_literal(expr) => true, | ||
| _ => false, | ||
| }; | ||
| let sugg_expr = if needs_parens { | ||
| format!("({})", src) | ||
| } else { | ||
| src | ||
| }; | ||
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| if let Some(sugg) = self.can_use_as_ref(expr) { | ||
| return Some(sugg); | ||
| } | ||
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@@ -374,6 +383,66 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> { | |
| None | ||
| } | ||
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| /// This function checks if the specified expression is a built-in range literal. | ||
| /// (See: `LoweringContext::lower_expr()` in `src/librustc/hir/lowering.rs`). | ||
| fn is_range_literal(&self, expr: &hir::Expr) -> bool { | ||
| use hir::{Path, QPath, ExprKind, TyKind}; | ||
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| // We support `::std::ops::Range` and `::core::ops::Range` prefixes | ||
| let is_range_path = |path: &Path| { | ||
| let mut segs = path.segments.iter() | ||
| .map(|seg| seg.ident.as_str()); | ||
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| if let (Some(root), Some(std_core), Some(ops), Some(range), None) = | ||
| (segs.next(), segs.next(), segs.next(), segs.next(), segs.next()) | ||
|
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| { | ||
| // "{{root}}" is the equivalent of `::` prefix in Path | ||
| root == "{{root}}" && (std_core == "std" || std_core == "core") | ||
| && ops == "ops" && range.starts_with("Range") | ||
| } else { | ||
| false | ||
| } | ||
| }; | ||
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| let span_is_range_literal = |span: &Span| { | ||
| // Check whether a span corresponding to a range expression | ||
| // is a range literal, rather than an explicit struct or `new()` call. | ||
| let source_map = self.tcx.sess.source_map(); | ||
| let end_point = source_map.end_point(*span); | ||
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| if let Ok(end_string) = source_map.span_to_snippet(end_point) { | ||
| !(end_string.ends_with("}") || end_string.ends_with(")")) | ||
| } else { | ||
| false | ||
| } | ||
| }; | ||
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| match expr.node { | ||
| // All built-in range literals but `..=` and `..` desugar to Structs | ||
| ExprKind::Struct(QPath::Resolved(None, ref path), _, _) | | ||
| // `..` desugars to its struct path | ||
| ExprKind::Path(QPath::Resolved(None, ref path)) => { | ||
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| return is_range_path(&path) && span_is_range_literal(&expr.span); | ||
| } | ||
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| // `..=` desugars into `::std::ops::RangeInclusive::new(...)` | ||
| ExprKind::Call(ref func, _) => { | ||
| if let ExprKind::Path(QPath::TypeRelative(ref ty, ref segment)) = func.node { | ||
| if let TyKind::Path(QPath::Resolved(None, ref path)) = ty.node { | ||
| let call_to_new = segment.ident.as_str() == "new"; | ||
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| return is_range_path(&path) && span_is_range_literal(&expr.span) | ||
| && call_to_new; | ||
| } | ||
| } | ||
| } | ||
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| _ => {} | ||
| } | ||
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| false | ||
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| } | ||
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| pub fn check_for_cast(&self, | ||
| err: &mut DiagnosticBuilder<'tcx>, | ||
| expr: &hir::Expr, | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,75 @@ | ||
| // run-rustfix | ||
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| // Regression test for changes introduced while fixing #54505 | ||
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| // This test uses non-literals for Ranges | ||
| // (expecting no parens with borrow suggestion) | ||
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| use std::ops::RangeBounds; | ||
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| // take a reference to any built-in range | ||
| fn take_range(_r: &impl RangeBounds<i8>) {} | ||
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| fn main() { | ||
| take_range(&std::ops::Range { start: 0, end: 1 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &std::ops::Range { start: 0, end: 1 } | ||
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| take_range(&::std::ops::Range { start: 0, end: 1 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &::std::ops::Range { start: 0, end: 1 } | ||
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| take_range(&std::ops::RangeFrom { start: 1 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &std::ops::RangeFrom { start: 1 } | ||
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| take_range(&::std::ops::RangeFrom { start: 1 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &::std::ops::RangeFrom { start: 1 } | ||
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| take_range(&std::ops::RangeFull {}); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &std::ops::RangeFull {} | ||
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| take_range(&::std::ops::RangeFull {}); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &::std::ops::RangeFull {} | ||
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| take_range(&std::ops::RangeInclusive::new(0, 1)); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &std::ops::RangeInclusive::new(0, 1) | ||
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| take_range(&::std::ops::RangeInclusive::new(0, 1)); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &::std::ops::RangeInclusive::new(0, 1) | ||
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| take_range(&std::ops::RangeTo { end: 5 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &std::ops::RangeTo { end: 5 } | ||
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| take_range(&::std::ops::RangeTo { end: 5 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &::std::ops::RangeTo { end: 5 } | ||
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| take_range(&std::ops::RangeToInclusive { end: 5 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &std::ops::RangeToInclusive { end: 5 } | ||
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| take_range(&::std::ops::RangeToInclusive { end: 5 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &::std::ops::RangeToInclusive { end: 5 } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,75 @@ | ||
| // run-rustfix | ||
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| // Regression test for changes introduced while fixing #54505 | ||
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| // This test uses non-literals for Ranges | ||
| // (expecting no parens with borrow suggestion) | ||
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| use std::ops::RangeBounds; | ||
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| // take a reference to any built-in range | ||
| fn take_range(_r: &impl RangeBounds<i8>) {} | ||
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| fn main() { | ||
| take_range(std::ops::Range { start: 0, end: 1 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &std::ops::Range { start: 0, end: 1 } | ||
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| take_range(::std::ops::Range { start: 0, end: 1 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &::std::ops::Range { start: 0, end: 1 } | ||
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| take_range(std::ops::RangeFrom { start: 1 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &std::ops::RangeFrom { start: 1 } | ||
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| take_range(::std::ops::RangeFrom { start: 1 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &::std::ops::RangeFrom { start: 1 } | ||
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| take_range(std::ops::RangeFull {}); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &std::ops::RangeFull {} | ||
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| take_range(::std::ops::RangeFull {}); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &::std::ops::RangeFull {} | ||
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| take_range(std::ops::RangeInclusive::new(0, 1)); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &std::ops::RangeInclusive::new(0, 1) | ||
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| take_range(::std::ops::RangeInclusive::new(0, 1)); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &::std::ops::RangeInclusive::new(0, 1) | ||
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| take_range(std::ops::RangeTo { end: 5 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &std::ops::RangeTo { end: 5 } | ||
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| take_range(::std::ops::RangeTo { end: 5 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &::std::ops::RangeTo { end: 5 } | ||
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| take_range(std::ops::RangeToInclusive { end: 5 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &std::ops::RangeToInclusive { end: 5 } | ||
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| take_range(::std::ops::RangeToInclusive { end: 5 }); | ||
| //~^ ERROR mismatched types [E0308] | ||
| //~| HELP consider borrowing here | ||
| //~| SUGGESTION &::std::ops::RangeToInclusive { end: 5 } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,147 @@ | ||
| error[E0308]: mismatched types | ||
| --> $DIR/issue-54505-no-literals.rs:16:16 | ||
| | | ||
| LL | take_range(std::ops::Range { start: 0, end: 1 }); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | | | ||
| | expected reference, found struct `std::ops::Range` | ||
| | help: consider borrowing here: `&std::ops::Range { start: 0, end: 1 }` | ||
| | | ||
| = note: expected type `&_` | ||
| found type `std::ops::Range<{integer}>` | ||
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| error[E0308]: mismatched types | ||
| --> $DIR/issue-54505-no-literals.rs:21:16 | ||
| | | ||
| LL | take_range(::std::ops::Range { start: 0, end: 1 }); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | | | ||
| | expected reference, found struct `std::ops::Range` | ||
| | help: consider borrowing here: `&::std::ops::Range { start: 0, end: 1 }` | ||
| | | ||
| = note: expected type `&_` | ||
| found type `std::ops::Range<{integer}>` | ||
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| error[E0308]: mismatched types | ||
| --> $DIR/issue-54505-no-literals.rs:26:16 | ||
| | | ||
| LL | take_range(std::ops::RangeFrom { start: 1 }); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | | | ||
| | expected reference, found struct `std::ops::RangeFrom` | ||
| | help: consider borrowing here: `&std::ops::RangeFrom { start: 1 }` | ||
| | | ||
| = note: expected type `&_` | ||
| found type `std::ops::RangeFrom<{integer}>` | ||
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| error[E0308]: mismatched types | ||
| --> $DIR/issue-54505-no-literals.rs:31:16 | ||
| | | ||
| LL | take_range(::std::ops::RangeFrom { start: 1 }); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | | | ||
| | expected reference, found struct `std::ops::RangeFrom` | ||
| | help: consider borrowing here: `&::std::ops::RangeFrom { start: 1 }` | ||
| | | ||
| = note: expected type `&_` | ||
| found type `std::ops::RangeFrom<{integer}>` | ||
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| error[E0308]: mismatched types | ||
| --> $DIR/issue-54505-no-literals.rs:36:16 | ||
| | | ||
| LL | take_range(std::ops::RangeFull {}); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^ | ||
| | | | ||
| | expected reference, found struct `std::ops::RangeFull` | ||
| | help: consider borrowing here: `&std::ops::RangeFull {}` | ||
| | | ||
| = note: expected type `&_` | ||
| found type `std::ops::RangeFull` | ||
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| error[E0308]: mismatched types | ||
| --> $DIR/issue-54505-no-literals.rs:41:16 | ||
| | | ||
| LL | take_range(::std::ops::RangeFull {}); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | | | ||
| | expected reference, found struct `std::ops::RangeFull` | ||
| | help: consider borrowing here: `&::std::ops::RangeFull {}` | ||
| | | ||
| = note: expected type `&_` | ||
| found type `std::ops::RangeFull` | ||
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| error[E0308]: mismatched types | ||
| --> $DIR/issue-54505-no-literals.rs:46:16 | ||
| | | ||
| LL | take_range(std::ops::RangeInclusive::new(0, 1)); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | | | ||
| | expected reference, found struct `std::ops::RangeInclusive` | ||
| | help: consider borrowing here: `&std::ops::RangeInclusive::new(0, 1)` | ||
| | | ||
| = note: expected type `&_` | ||
| found type `std::ops::RangeInclusive<{integer}>` | ||
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| error[E0308]: mismatched types | ||
| --> $DIR/issue-54505-no-literals.rs:51:16 | ||
| | | ||
| LL | take_range(::std::ops::RangeInclusive::new(0, 1)); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | | | ||
| | expected reference, found struct `std::ops::RangeInclusive` | ||
| | help: consider borrowing here: `&::std::ops::RangeInclusive::new(0, 1)` | ||
| | | ||
| = note: expected type `&_` | ||
| found type `std::ops::RangeInclusive<{integer}>` | ||
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| error[E0308]: mismatched types | ||
| --> $DIR/issue-54505-no-literals.rs:56:16 | ||
| | | ||
| LL | take_range(std::ops::RangeTo { end: 5 }); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | | | ||
| | expected reference, found struct `std::ops::RangeTo` | ||
| | help: consider borrowing here: `&std::ops::RangeTo { end: 5 }` | ||
| | | ||
| = note: expected type `&_` | ||
| found type `std::ops::RangeTo<{integer}>` | ||
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| error[E0308]: mismatched types | ||
| --> $DIR/issue-54505-no-literals.rs:61:16 | ||
| | | ||
| LL | take_range(::std::ops::RangeTo { end: 5 }); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | | | ||
| | expected reference, found struct `std::ops::RangeTo` | ||
| | help: consider borrowing here: `&::std::ops::RangeTo { end: 5 }` | ||
| | | ||
| = note: expected type `&_` | ||
| found type `std::ops::RangeTo<{integer}>` | ||
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| error[E0308]: mismatched types | ||
| --> $DIR/issue-54505-no-literals.rs:66:16 | ||
| | | ||
| LL | take_range(std::ops::RangeToInclusive { end: 5 }); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | | | ||
| | expected reference, found struct `std::ops::RangeToInclusive` | ||
| | help: consider borrowing here: `&std::ops::RangeToInclusive { end: 5 }` | ||
| | | ||
| = note: expected type `&_` | ||
| found type `std::ops::RangeToInclusive<{integer}>` | ||
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| error[E0308]: mismatched types | ||
| --> $DIR/issue-54505-no-literals.rs:71:16 | ||
| | | ||
| LL | take_range(::std::ops::RangeToInclusive { end: 5 }); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | | | ||
| | expected reference, found struct `std::ops::RangeToInclusive` | ||
| | help: consider borrowing here: `&::std::ops::RangeToInclusive { end: 5 }` | ||
| | | ||
| = note: expected type `&_` | ||
| found type `std::ops::RangeToInclusive<{integer}>` | ||
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| error: aborting due to 12 previous errors | ||
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| For more information about this error, try `rustc --explain E0308`. |
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I might be alone in this (cc @estebank), but I think for a short path like this, a more explicit approach (like below) is more readable. (I specifically don't like splitting on "|" because it feels a little too ad hoc.)
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That's a great suggestion! I was looking for something concise like this syntax-wise, it didn't occur to me that I could use
.next()and rely on it returningNonewhen there's no more elements.