bjoernager/rust
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Use ZST for fmt unsafety

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This allows the format_args! macro to keep the pre-expansion code out of
the unsafe block without doing gymnastics with nested `match`
expressions. This reduces codegen.
This commit is contained in:
Cameron Steffen 2021-09-21 00:56:45 -05:00
parent d37f1091e8
commit 4873ebee4c
1 changed files with 15 additions and 20 deletions
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35
clippy_utils/src/higher.rs
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@ -524,28 +524,12 @@ impl FormatArgsExpn<'tcx> {
if let ExpnKind::Macro(_, name) = expr.span.ctxt().outer_expn_data().kind; if let ExpnKind::Macro(_, name) = expr.span.ctxt().outer_expn_data().kind;
let name = name.as_str(); let name = name.as_str();
if name.ends_with("format_args") || name.ends_with("format_args_nl"); if name.ends_with("format_args") || name.ends_with("format_args_nl");
if let ExprKind::Call(_, args) = expr.kind;
if let ExprKind::Match(inner_match, [arm], _) = expr.kind; if let Some((strs_ref, args, fmt_expr)) = match args {
// `match match`, if you will
if let ExprKind::Match(args, [inner_arm], _) = inner_match.kind;
if let ExprKind::Tup(value_args) = args.kind;
if let Some(value_args) = value_args
.iter()
.map(|e| match e.kind {
ExprKind::AddrOf(_, _, e) => Some(e),
_ => None,
})
.collect();
if let ExprKind::Array(args) = inner_arm.body.kind;
if let ExprKind::Block(Block { stmts: [], expr: Some(expr), .. }, _) = arm.body.kind;
if let ExprKind::Call(_, call_args) = expr.kind;
if let Some((strs_ref, fmt_expr)) = match call_args {
// Arguments::new_v1 // Arguments::new_v1
[strs_ref, _] => Some((strs_ref, None)), [strs_ref, args] => Some((strs_ref, args, None)),
// Arguments::new_v1_formatted // Arguments::new_v1_formatted
[strs_ref, _, fmt_expr] => Some((strs_ref, Some(fmt_expr))), [strs_ref, args, fmt_expr, _unsafe_arg] => Some((strs_ref, args, Some(fmt_expr))),
_ => None, _ => None,
}; };
if let ExprKind::AddrOf(BorrowKind::Ref, _, strs_arr) = strs_ref.kind; if let ExprKind::AddrOf(BorrowKind::Ref, _, strs_arr) = strs_ref.kind;
@ -561,6 +545,17 @@ impl FormatArgsExpn<'tcx> {
None None
}) })
.collect(); .collect();
if let ExprKind::AddrOf(BorrowKind::Ref, _, args) = args.kind;
if let ExprKind::Match(args, [arm], _) = args.kind;
if let ExprKind::Tup(value_args) = args.kind;
if let Some(value_args) = value_args
.iter()
.map(|e| match e.kind {
ExprKind::AddrOf(_, _, e) => Some(e),
_ => None,
})
.collect();
if let ExprKind::Array(args) = arm.body.kind;
then { then {
Some(FormatArgsExpn { Some(FormatArgsExpn {
format_string_span: strs_ref.span, format_string_span: strs_ref.span,