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Check all arg indexes before removing inlined format args.

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This commit is contained in:
Mara Bos 2023-01-13 19:19:47 +01:00
parent 0554401fcc
commit df8c14ca61
1 changed files with 15 additions and 13 deletions
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28
compiler/rustc_ast_lowering/src/format.rs
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@ -103,10 +103,8 @@ fn flatten_format_args(mut fmt: Cow<'_, FormatArgs>) -> Cow<'_, FormatArgs> {
///
/// `format_args!("Hello, World! {}", 123)`.
fn inline_literals(mut fmt: Cow<'_, FormatArgs>) -> Cow<'_, FormatArgs> {
// None: Not sure yet.
// Some(true): Remove, because it was inlined. (Might be set to false later if it is used in another way.)
// Some(false): Do not remove, because some non-inlined placeholder uses it.
let mut remove = vec![None; fmt.arguments.all_args().len()];
let mut was_inlined = vec![false; fmt.arguments.all_args().len()];
let mut inlined_anything = false;
for i in 0..fmt.template.len() {
let FormatArgsPiece::Placeholder(placeholder) = &fmt.template[i] else { continue };
@ -123,30 +121,34 @@ fn inline_literals(mut fmt: Cow<'_, FormatArgs>) -> Cow<'_, FormatArgs> {
let fmt = fmt.to_mut();
// Replace the placeholder with the literal.
fmt.template[i] = FormatArgsPiece::Literal(s);
// Only remove it wasn't set to 'do not remove'.
remove[arg_index].get_or_insert(true);
} else {
// Never remove an argument that's used by a non-inlined placeholder,
// even if this argument is inlined in another place.
remove[arg_index] = Some(false);
was_inlined[arg_index] = true;
inlined_anything = true;
}
}
// Remove the arguments that were inlined.
if remove.iter().any(|&x| x == Some(true)) {
if inlined_anything {
let fmt = fmt.to_mut();
let mut remove = was_inlined;
// Don't remove anything that's still used.
for_all_argument_indexes(&mut fmt.template, |index| remove[*index] = false);
// Drop all the arguments that are marked for removal.
let mut remove_it = remove.iter();
fmt.arguments.all_args_mut().retain(|_| remove_it.next() != Some(&Some(true)));
fmt.arguments.all_args_mut().retain(|_| remove_it.next() != Some(&true));
// Calculate the mapping of old to new indexes for the remaining arguments.
let index_map: Vec<usize> = remove
.into_iter()
.scan(0, |i, remove| {
let mapped = *i;
*i += (remove != Some(true)) as usize;
*i += !remove as usize;
Some(mapped)
})
.collect();
// Correct the indexes that refer to arguments that have shifted position.
for_all_argument_indexes(&mut fmt.template, |index| *index = index_map[*index]);
}