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

This reverts commit e6c02aad9345925cfed74f86b414c4d0715d381b.

Keeps the code improvements from the PR and the test (as a known-bug).

1 files changed, 2 insertions, 35 deletions

diff --git a/compiler/rustc_parse_format/src/lib.rs b/compiler/rustc_parse_format/src/lib.rs
index 1eb227503f2..7b016cadac3 100644
--- a/compiler/rustc_parse_format/src/lib.rs
+++ b/compiler/rustc_parse_format/src/lib.rs
@@ -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);