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Revert "Improve heuristics whether format_args string is a source literal" #107041

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merged 1 commit into from
Jan 19, 2023
Merged

Revert "Improve heuristics whether format_args string is a source literal" #107041

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37 changes: 2 additions & 35 deletions compiler/rustc_parse_format/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -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 {
Expand All @@ -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() {
Expand Down Expand Up @@ -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);
Expand Down
12 changes: 12 additions & 0 deletions tests/ui/fmt/auxiliary/format-string-proc-macro.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@ pub fn err_with_input_span(input: TokenStream) -> TokenStream {
TokenStream::from(TokenTree::Literal(lit))
}


#[proc_macro]
pub fn respan_to_invalid_format_literal(input: TokenStream) -> TokenStream {
let mut s = Literal::string("{");
Expand All @@ -38,3 +39,14 @@ pub fn respan_to_invalid_format_literal(input: TokenStream) -> TokenStream {
TokenTree::from(Group::new(Delimiter::Parenthesis, TokenTree::from(s).into())),
])
}

#[proc_macro]
pub fn capture_a_with_prepended_space_preserve_span(input: TokenStream) -> TokenStream {
let mut s = Literal::string(" {a}");
s.set_span(input.into_iter().next().unwrap().span());
TokenStream::from_iter([
TokenTree::from(Ident::new("format", Span::call_site())),
TokenTree::from(Punct::new('!', Spacing::Alone)),
TokenTree::from(Group::new(Delimiter::Parenthesis, TokenTree::from(s).into())),
])
}
9 changes: 9 additions & 0 deletions tests/ui/fmt/indoc-issue-106408.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
// aux-build:format-string-proc-macro.rs
// check-pass

extern crate format_string_proc_macro;

fn main() {
let a = 0;
format_string_proc_macro::capture_a_with_prepended_space_preserve_span!("{a}");
}
9 changes: 7 additions & 2 deletions tests/ui/fmt/respanned-literal-issue-106191.rs
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Original file line number Diff line number Diff line change
@@ -1,10 +1,15 @@
// aux-build:format-string-proc-macro.rs
// check-fail
// known-bug: #106191
// unset-rustc-env:RUST_BACKTRACE
// had to be reverted
// error-pattern:internal compiler error
// failure-status:101
// dont-check-compiler-stderr

extern crate format_string_proc_macro;

fn main() {
format_string_proc_macro::respan_to_invalid_format_literal!("¡");
//~^ ERROR invalid format string: expected `'}'` but string was terminated
format_args!(r#concat!("¡ {"));
//~^ ERROR invalid format string: expected `'}'` but string was terminated
}
21 changes: 2 additions & 19 deletions tests/ui/fmt/respanned-literal-issue-106191.stderr
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Original file line number Diff line number Diff line change
@@ -1,19 +1,2 @@
error: invalid format string: expected `'}'` but string was terminated
--> $DIR/respanned-literal-issue-106191.rs:6:65
|
LL | format_string_proc_macro::respan_to_invalid_format_literal!("¡");
| ^^^ expected `'}'` in format string
|
= note: if you intended to print `{`, you can escape it using `{{`

error: invalid format string: expected `'}'` but string was terminated
--> $DIR/respanned-literal-issue-106191.rs:8:18
|
LL | format_args!(r#concat!("¡ {"));
| ^^^^^^^^^^^^^^^^^^^^^^^ expected `'}'` in format string
|
= note: if you intended to print `{`, you can escape it using `{{`
= note: this error originates in the macro `concat` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to 2 previous errors

query stack during panic:
end of query stack