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Improve closure dummy capture suggestion in macros.

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This commit is contained in:
Mara Bos 2021-08-31 22:17:51 +02:00
parent 0a84708edc
commit 7189c85413
1 changed files with 26 additions and 9 deletions
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35
compiler/rustc_typeck/src/check/upvar.rs
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@ -47,7 +47,7 @@ use rustc_middle::ty::{
};
use rustc_session::lint;
use rustc_span::sym;
use rustc_span::{BytePos, MultiSpan, Pos, Span, Symbol, DUMMY_SP};
use rustc_span::{BytePos, MultiSpan, Pos, Span, Symbol};
use rustc_trait_selection::infer::InferCtxtExt;
use rustc_data_structures::stable_map::FxHashMap;
@ -680,15 +680,32 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
migrated_variables_concat
);
// If the body was entirely expanded from a macro
// invocation, i.e. the body is not contained inside the
// closure span, then we walk up the expansion until we
// find the span before the expansion.
let closure_body_span = self.tcx.hir().span(body_id.hir_id)
.find_ancestor_inside(closure_span)
.unwrap_or(DUMMY_SP);
let mut closure_body_span = {
// If the body was entirely expanded from a macro
// invocation, i.e. the body is not contained inside the
// closure span, then we walk up the expansion until we
// find the span before the expansion.
let s = self.tcx.hir().span(body_id.hir_id);
s.find_ancestor_inside(closure_span).unwrap_or(s)
};
if let Ok(mut s) = self.tcx.sess.source_map().span_to_snippet(closure_body_span) {
if s.starts_with('$') {
// Looks like a macro fragment. Try to find the real block.
if let Some(hir::Node::Expr(&hir::Expr {
kind: hir::ExprKind::Block(block, ..), ..
})) = self.tcx.hir().find(body_id.hir_id) {
// If the body is a block (with `{..}`), we use the span of that block.
// E.g. with a `|| $body` expanded from a `m!({ .. })`, we use `{ .. }`, and not `$body`.
// Since we know it's a block, we know we can insert the `let _ = ..` without
// breaking the macro syntax.
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(block.span) {
closure_body_span = block.span;
s = snippet;
}
}
}
if let Ok(s) = self.tcx.sess.source_map().span_to_snippet(closure_body_span) {
let mut lines = s.lines();
let line1 = lines.next().unwrap_or_default();