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Revert "Improve heuristics whether format_args string is a source literal"

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This reverts commit e6c02aad93.

Keeps the code improvements from the PR and the test (as a known-bug).
This commit is contained in:
Nilstrieb 2023-01-18 19:47:22 +01:00
parent 1f72129ffe
commit a8086cf9df
5 changed files with 32 additions and 56 deletions
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37
compiler/rustc_parse_format/src/lib.rs
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@ -20,7 +20,6 @@ pub use Flag::*;
pub use Piece::*;
pub use Position::*;
use rustc_lexer::unescape;
use std::iter;
use std::str;
use std::string;
@ -314,11 +313,12 @@ impl<'a> Parser<'a> {
append_newline: bool,
mode: ParseMode,
) -> Parser<'a> {
let input_string_kind = find_width_map_from_snippet(s, snippet, style);
let input_string_kind = find_width_map_from_snippet(snippet, style);
let (width_map, is_literal) = match input_string_kind {
InputStringKind::Literal { width_mappings } => (width_mappings, true),
InputStringKind::NotALiteral => (Vec::new(), false),
};
Parser {
mode,
input: s,
@ -856,7 +856,6 @@ impl<'a> Parser<'a> {
/// written code (code snippet) and the `InternedString` that gets processed in the `Parser`
/// in order to properly synthesise the intra-string `Span`s for error diagnostics.
fn find_width_map_from_snippet(
input: &str,
snippet: Option<string::String>,
str_style: Option<usize>,
) -> InputStringKind {
@ -869,27 +868,8 @@ fn find_width_map_from_snippet(
return InputStringKind::Literal { width_mappings: Vec::new() };
}
// Strip quotes.
let snippet = &snippet[1..snippet.len() - 1];
// Macros like `println` add a newline at the end. That technically doens't make them "literals" anymore, but it's fine
// since we will never need to point our spans there, so we lie about it here by ignoring it.
// Since there might actually be newlines in the source code, we need to normalize away all trailing newlines.
// If we only trimmed it off the input, `format!("\n")` would cause a mismatch as here we they actually match up.
// Alternatively, we could just count the trailing newlines and only trim one from the input if they don't match up.
let input_no_nl = input.trim_end_matches('\n');
let Ok(unescaped) = unescape_string(snippet) else {
return InputStringKind::NotALiteral;
};
let unescaped_no_nl = unescaped.trim_end_matches('\n');
if unescaped_no_nl != input_no_nl {
// The source string that we're pointing at isn't our input, so spans pointing at it will be incorrect.
// This can for example happen with proc macros that respan generated literals.
return InputStringKind::NotALiteral;
}
let mut s = snippet.char_indices();
let mut width_mappings = vec![];
while let Some((pos, c)) = s.next() {
@ -972,19 +952,6 @@ fn find_width_map_from_snippet(
InputStringKind::Literal { width_mappings }
}
fn unescape_string(string: &str) -> Result<string::String, unescape::EscapeError> {
let mut buf = string::String::new();
let mut error = Ok(());
unescape::unescape_literal(string, unescape::Mode::Str, &mut |_, unescaped_char| {
match unescaped_char {
Ok(c) => buf.push(c),
Err(err) => error = Err(err),
}
});
error.map(|_| buf)
}
// Assert a reasonable size for `Piece`
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
rustc_data_structures::static_assert_size!(Piece<'_>, 16);