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Rollup merge of #89895 - camsteffen:for-loop-head-span, r=davidtwco

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Don't mark for loop iter expression as desugared

We typically don't mark spans of lowered things as desugared. This helps Clippy rightly discern when code is (not) from expansion. This was discovered by ``@flip1995`` at https://github.com/rust-lang/rust-clippy/pull/7789#issuecomment-939289501.
This commit is contained in:
Yuki Okushi 2021-10-22 19:42:45 +09:00 • committed by GitHub
commit 91fb223f59
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6 changed files with 65 additions and 74 deletions
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39
compiler/rustc_ast_lowering/src/expr.rs
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@ -1332,15 +1332,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
body: &Block,
opt_label: Option<Label>,
) -> hir::Expr<'hir> {
let orig_head_span = head.span;
// expand <head>
let mut head = self.lower_expr_mut(head);
let desugared_span = self.mark_span_with_reason(
DesugaringKind::ForLoop(ForLoopLoc::Head),
orig_head_span,
None,
);
head.span = self.lower_span(desugared_span);
let head = self.lower_expr_mut(head);
let desugared_span =
self.mark_span_with_reason(DesugaringKind::ForLoop(ForLoopLoc::Head), head.span, None);
let e_span = self.lower_span(e.span);
let iter = Ident::with_dummy_span(sym::iter);
@ -1354,23 +1350,24 @@ impl<'hir> LoweringContext<'_, 'hir> {
// `::std::option::Option::Some(val) => __next = val`
let pat_arm = {
let val_ident = Ident::with_dummy_span(sym::val);
let (val_pat, val_pat_hid) = self.pat_ident(pat.span, val_ident);
let val_expr = self.expr_ident(pat.span, val_ident, val_pat_hid);
let next_expr = self.expr_ident(pat.span, next_ident, next_pat_hid);
let pat_span = self.lower_span(pat.span);
let (val_pat, val_pat_hid) = self.pat_ident(pat_span, val_ident);
let val_expr = self.expr_ident(pat_span, val_ident, val_pat_hid);
let next_expr = self.expr_ident(pat_span, next_ident, next_pat_hid);
let assign = self.arena.alloc(self.expr(
pat.span,
hir::ExprKind::Assign(next_expr, val_expr, self.lower_span(pat.span)),
pat_span,
hir::ExprKind::Assign(next_expr, val_expr, self.lower_span(pat_span)),
ThinVec::new(),
));
let some_pat = self.pat_some(pat.span, val_pat);
let some_pat = self.pat_some(pat_span, val_pat);
self.arm(some_pat, assign)
};
// `::std::option::Option::None => break`
let break_arm = {
let break_expr =
self.with_loop_scope(e.id, |this| this.expr_break_alloc(e.span, ThinVec::new()));
let pat = self.pat_none(e.span);
self.with_loop_scope(e.id, |this| this.expr_break_alloc(e_span, ThinVec::new()));
let pat = self.pat_none(e_span);
self.arm(pat, break_expr)
};
@ -1416,10 +1413,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
let body_block = self.with_loop_scope(e.id, |this| this.lower_block(body, false));
let body_expr = self.expr_block(body_block, ThinVec::new());
let body_stmt = self.stmt_expr(body.span, body_expr);
let body_stmt = self.stmt_expr(body_block.span, body_expr);
let loop_block = self.block_all(
e.span,
e_span,
arena_vec![self; next_let, match_stmt, pat_let, body_stmt],
None,
);
@ -1429,7 +1426,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
loop_block,
self.lower_label(opt_label),
hir::LoopSource::ForLoop,
self.lower_span(e.span.with_hi(orig_head_span.hi())),
self.lower_span(e_span.with_hi(head.span.hi())),
);
let loop_expr = self.arena.alloc(hir::Expr {
hir_id: self.lower_node_id(e.id),
@ -1442,7 +1439,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
let into_iter_span = self.mark_span_with_reason(
DesugaringKind::ForLoop(ForLoopLoc::IntoIter),
orig_head_span,
head.span,
None,
);
@ -1458,7 +1455,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
// #82462: to correctly diagnose borrow errors, the block that contains
// the iter expr needs to have a span that covers the loop body.
let desugared_full_span =
self.mark_span_with_reason(DesugaringKind::ForLoop(ForLoopLoc::Head), e.span, None);
self.mark_span_with_reason(DesugaringKind::ForLoop(ForLoopLoc::Head), e_span, None);
let match_expr = self.arena.alloc(self.expr_match(
desugared_full_span,