bjoernager/rust
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Do not modify mutability of simple bindings.

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This commit removes the modification of the mutability of simple
bindings. While the mutability isn't used, it is important that it is
kept so that the input to procedural macros matches what the user wrote.
This commit also modifies the span of the binding mode so that it is
considered a compiler desugaring and won't be linted against for being
unused..
This commit is contained in:
David Wood 2019-05-09 19:10:27 +01:00
parent e57c7b859d
commit dcd3cf7017
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GPG key ID: 01760B4F9F53F154
4 changed files with 46 additions and 44 deletions
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23
src/libsyntax/parse/parser.rs
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@ -50,7 +50,10 @@ use crate::symbol::{Symbol, keywords};
use errors::{Applicability, DiagnosticBuilder, DiagnosticId, FatalError};
use rustc_target::spec::abi::{self, Abi};
use syntax_pos::{Span, MultiSpan, BytePos, FileName};
use syntax_pos::{
Span, MultiSpan, BytePos, FileName,
hygiene::CompilerDesugaringKind,
};
use log::{debug, trace};
use std::borrow::Cow;
@ -8741,6 +8744,15 @@ impl<'a> Parser<'a> {
// statement.
let (binding_mode, ident, is_simple_pattern) = match input.pat.node {
PatKind::Ident(binding_mode @ BindingMode::ByValue(_), ident, _) => {
// Simple patterns like this don't have a generated argument, but they are
// moved into the closure with a statement, so any `mut` bindings on the
// argument will be unused. This binding mode can't be removed, because
// this would affect the input to procedural macros, but they can have
// their span marked as being the result of a compiler desugaring so
// that they aren't linted against.
input.pat.span = self.sess.source_map().mark_span_with_reason(
CompilerDesugaringKind::Async, span, None);
(binding_mode, ident, true)
}
_ => (BindingMode::ByValue(Mutability::Mutable), ident, false),
@ -8810,15 +8822,6 @@ impl<'a> Parser<'a> {
})
};
// Remove mutability from arguments. If this is not a simple pattern,
// those arguments are replaced by `__argN`, so there is no need to do this.
if let PatKind::Ident(BindingMode::ByValue(mutability @ Mutability::Mutable), ..) =
&mut input.pat.node
{
assert!(is_simple_pattern);
*mutability = Mutability::Immutable;
}
let move_stmt = Stmt { id, node: StmtKind::Local(P(move_local)), span };
arguments.push(AsyncArgument { ident, arg, pat_stmt, move_stmt });
}