Rust: handle UTF-8 decoding errors

rust/extractor/src/main.rs

@@ -1,13 +1,48 @@
 use anyhow::Context;
 use ra_ap_ide_db::line_index::LineIndex;
 use ra_ap_parser::Edition;
+use std::borrow::Cow;
 mod archive;
 mod config;
 pub mod generated;
 mod translate;
 pub mod trap;
 use ra_ap_syntax::ast::SourceFile;
-use ra_ap_syntax::AstNode;
+use ra_ap_syntax::{AstNode, SyntaxError, TextRange, TextSize};
+
+fn from_utf8_lossy(v: &[u8]) -> (Cow<'_, str>, Option<SyntaxError>) {
+    let mut iter = v.utf8_chunks();
+    let (first_valid, first_invalid) = if let Some(chunk) = iter.next() {
+        let valid = chunk.valid();
+        let invalid = chunk.invalid();
+        if invalid.is_empty() {
+            debug_assert_eq!(valid.len(), v.len());
+            return (Cow::Borrowed(valid), None);
+        }
+        (valid, invalid)
+    } else {
+        return (Cow::Borrowed(""), None);
+    };
+
+    const REPLACEMENT: &str = "\u{FFFD}";
+    let error_start = first_valid.len() as u32;
+    let error_end = error_start + first_invalid.len() as u32;
+    let error_range = TextRange::new(TextSize::new(error_start), TextSize::new(error_end));
+    let error = SyntaxError::new("invalid utf-8 sequence".to_owned(), error_range);
+    let mut res = String::with_capacity(v.len());
+    res.push_str(first_valid);
+
+    res.push_str(REPLACEMENT);
+
+    for chunk in iter {
+        res.push_str(chunk.valid());
+        if !chunk.invalid().is_empty() {
+            res.push_str(REPLACEMENT);
+        }
+    }
+
+    (Cow::Owned(res), Some(error))
+}
 
 fn extract(
     archiver: &archive::Archiver,
@@ -18,13 +53,15 @@ fn extract(
     let file = std::fs::canonicalize(&file).unwrap_or(file);
     archiver.archive(&file);
     let input = std::fs::read(&file)?;
-    let input = String::from_utf8(input)?;
+    let (input, err) = from_utf8_lossy(&input);
     let line_index = LineIndex::new(&input);
     let display_path = file.to_string_lossy();
     let mut trap = traps.create("source", &file);
     let label = trap.emit_file(&file);
     let mut translator = translate::Translator::new(trap, label, line_index);
-
+    if let Some(err) = err {
+        translator.emit_parse_error(display_path.as_ref(), err);
+    }
     let parse = ra_ap_syntax::ast::SourceFile::parse(&input, Edition::CURRENT);
     for err in parse.errors() {
         translator.emit_parse_error(display_path.as_ref(), err);