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Auto merge of rust-lang#107041 - Nilstrieb:back-to-being-clueless-whether-it-really-is-a-literal, r=compiler-errors
Revert "Improve heuristics whether `format_args` string is a source literal" This reverts commit e6c02aa (from rust-lang#106195). Keeps the code improvements from the PR and the test (as a known-bug). Works around rust-lang#106408 while a proper fix is discussed more thoroughly in rust-lang#106505, as proposed by `@tmandry.` Reopens rust-lang#106191 r? compiler-errors
2 parents 333ee6c + a8086cf commit 8b11574

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5 files changed

+32
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‎compiler/rustc_parse_format/src/lib.rs

Lines changed: 2 additions & 35 deletions
Original file line numberDiff line numberDiff line change
@@ -20,7 +20,6 @@ pub use Flag::*;
2020
pub use Piece::*;
2121
pub use Position::*;
2222

23-
use rustc_lexer::unescape;
2423
use std::iter;
2524
use std::str;
2625
use std::string;
@@ -314,11 +313,12 @@ impl<'a> Parser<'a> {
314313
append_newline: bool,
315314
mode: ParseMode,
316315
) -> Parser<'a> {
317-
let input_string_kind = find_width_map_from_snippet(s, snippet, style);
316+
let input_string_kind = find_width_map_from_snippet(snippet, style);
318317
let (width_map, is_literal) = match input_string_kind {
319318
InputStringKind::Literal { width_mappings } => (width_mappings, true),
320319
InputStringKind::NotALiteral => (Vec::new(), false),
321320
};
321+
322322
Parser {
323323
mode,
324324
input: s,
@@ -856,7 +856,6 @@ impl<'a> Parser<'a> {
856856
/// written code (code snippet) and the `InternedString` that gets processed in the `Parser`
857857
/// in order to properly synthesise the intra-string `Span`s for error diagnostics.
858858
fn find_width_map_from_snippet(
859-
input: &str,
860859
snippet: Option<string::String>,
861860
str_style: Option<usize>,
862861
) -> InputStringKind {
@@ -869,27 +868,8 @@ fn find_width_map_from_snippet(
869868
return InputStringKind::Literal { width_mappings: Vec::new() };
870869
}
871870

872-
// Strip quotes.
873871
let snippet = &snippet[1..snippet.len() - 1];
874872

875-
// Macros like `println` add a newline at the end. That technically doens't make them "literals" anymore, but it's fine
876-
// since we will never need to point our spans there, so we lie about it here by ignoring it.
877-
// Since there might actually be newlines in the source code, we need to normalize away all trailing newlines.
878-
// If we only trimmed it off the input, `format!("\n")` would cause a mismatch as here we they actually match up.
879-
// Alternatively, we could just count the trailing newlines and only trim one from the input if they don't match up.
880-
let input_no_nl = input.trim_end_matches('\n');
881-
let Ok(unescaped) = unescape_string(snippet) else {
882-
return InputStringKind::NotALiteral;
883-
};
884-
885-
let unescaped_no_nl = unescaped.trim_end_matches('\n');
886-
887-
if unescaped_no_nl != input_no_nl {
888-
// The source string that we're pointing at isn't our input, so spans pointing at it will be incorrect.
889-
// This can for example happen with proc macros that respan generated literals.
890-
return InputStringKind::NotALiteral;
891-
}
892-
893873
let mut s = snippet.char_indices();
894874
let mut width_mappings = vec![];
895875
while let Some((pos, c)) = s.next() {
@@ -972,19 +952,6 @@ fn find_width_map_from_snippet(
972952
InputStringKind::Literal { width_mappings }
973953
}
974954

975-
fn unescape_string(string: &str) -> Result<string::String, unescape::EscapeError> {
976-
let mut buf = string::String::new();
977-
let mut error = Ok(());
978-
unescape::unescape_literal(string, unescape::Mode::Str, &mut |_, unescaped_char| {
979-
match unescaped_char {
980-
Ok(c) => buf.push(c),
981-
Err(err) => error = Err(err),
982-
}
983-
});
984-
985-
error.map(|_| buf)
986-
}
987-
988955
// Assert a reasonable size for `Piece`
989956
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
990957
rustc_data_structures::static_assert_size!(Piece<'_>, 16);

‎tests/ui/fmt/auxiliary/format-string-proc-macro.rs

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -28,6 +28,7 @@ pub fn err_with_input_span(input: TokenStream) -> TokenStream {
2828
TokenStream::from(TokenTree::Literal(lit))
2929
}
3030

31+
3132
#[proc_macro]
3233
pub fn respan_to_invalid_format_literal(input: TokenStream) -> TokenStream {
3334
let mut s = Literal::string("{");
@@ -38,3 +39,14 @@ pub fn respan_to_invalid_format_literal(input: TokenStream) -> TokenStream {
3839
TokenTree::from(Group::new(Delimiter::Parenthesis, TokenTree::from(s).into())),
3940
])
4041
}
42+
43+
#[proc_macro]
44+
pub fn capture_a_with_prepended_space_preserve_span(input: TokenStream) -> TokenStream {
45+
let mut s = Literal::string(" {a}");
46+
s.set_span(input.into_iter().next().unwrap().span());
47+
TokenStream::from_iter([
48+
TokenTree::from(Ident::new("format", Span::call_site())),
49+
TokenTree::from(Punct::new('!', Spacing::Alone)),
50+
TokenTree::from(Group::new(Delimiter::Parenthesis, TokenTree::from(s).into())),
51+
])
52+
}

‎tests/ui/fmt/indoc-issue-106408.rs

Lines changed: 9 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,9 @@
1+
// aux-build:format-string-proc-macro.rs
2+
// check-pass
3+
4+
extern crate format_string_proc_macro;
5+
6+
fn main() {
7+
let a = 0;
8+
format_string_proc_macro::capture_a_with_prepended_space_preserve_span!("{a}");
9+
}

‎tests/ui/fmt/respanned-literal-issue-106191.rs

Lines changed: 7 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,10 +1,15 @@
11
// aux-build:format-string-proc-macro.rs
2+
// check-fail
3+
// known-bug: #106191
4+
// unset-rustc-env:RUST_BACKTRACE
5+
// had to be reverted
6+
// error-pattern:internal compiler error
7+
// failure-status:101
8+
// dont-check-compiler-stderr
29

310
extern crate format_string_proc_macro;
411

512
fn main() {
613
format_string_proc_macro::respan_to_invalid_format_literal!("¡");
7-
//~^ ERROR invalid format string: expected `'}'` but string was terminated
814
format_args!(r#concat!("¡ {"));
9-
//~^ ERROR invalid format string: expected `'}'` but string was terminated
1015
}

‎tests/ui/fmt/respanned-literal-issue-106191.stderr

Lines changed: 2 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -1,19 +1,2 @@
1-
error: invalid format string: expected `'}'` but string was terminated
2-
--> $DIR/respanned-literal-issue-106191.rs:6:65
3-
|
4-
LL | format_string_proc_macro::respan_to_invalid_format_literal!("¡");
5-
| ^^^ expected `'}'` in format string
6-
|
7-
= note: if you intended to print `{`, you can escape it using `{{`
8-
9-
error: invalid format string: expected `'}'` but string was terminated
10-
--> $DIR/respanned-literal-issue-106191.rs:8:18
11-
|
12-
LL | format_args!(r#concat!("¡ {"));
13-
| ^^^^^^^^^^^^^^^^^^^^^^^ expected `'}'` in format string
14-
|
15-
= note: if you intended to print `{`, you can escape it using `{{`
16-
= note: this error originates in the macro `concat` (in Nightly builds, run with -Z macro-backtrace for more info)
17-
18-
error: aborting due to 2 previous errors
19-
1+
query stack during panic:
2+
end of query stack

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