Fix the start/end byte positions in the compiler JSON output

4 files changed, 199 insertions, 4 deletions

diff --git a/src/libsyntax/json.rs b/src/libsyntax/json.rs
index 2423e1070fc..aa0b4117174 100644
--- a/src/libsyntax/json.rs
+++ b/src/libsyntax/json.rs
@@ -25,6 +25,9 @@ use std::sync::{Arc, Mutex};
 
 use rustc_serialize::json::{as_json, as_pretty_json};
 
+#[cfg(test)]
+mod tests;
+
 pub struct JsonEmitter {
     dst: Box<dyn Write + Send>,
     registry: Option<Registry>,
@@ -332,8 +335,8 @@ impl DiagnosticSpan {
 
         DiagnosticSpan {
             file_name: start.file.name.to_string(),
-            byte_start: span.lo().0 - start.file.start_pos.0,
-            byte_end: span.hi().0 - start.file.start_pos.0,
+            byte_start: start.file.original_relative_byte_pos(span.lo()).0,
+            byte_end: start.file.original_relative_byte_pos(span.hi()).0,
             line_start: start.line,
             line_end: end.line,
             column_start: start.col.0 + 1,
diff --git a/src/libsyntax/json/tests.rs b/src/libsyntax/json/tests.rs
new file mode 100644
index 00000000000..eb0d9ef3947
--- /dev/null
+++ b/src/libsyntax/json/tests.rs
@@ -0,0 +1,186 @@
+use super::*;
+
+use crate::json::JsonEmitter;
+use crate::source_map::{FilePathMapping, SourceMap};
+use crate::tests::Shared;
+use crate::with_default_globals;
+
+use errors::emitter::{ColorConfig, HumanReadableErrorType};
+use errors::Handler;
+use rustc_serialize::json::decode;
+use syntax_pos::{BytePos, Span};
+
+use std::str;
+
+#[derive(RustcDecodable, Debug, PartialEq, Eq)]
+struct TestData {
+    spans: Vec<SpanTestData>,
+}
+
+#[derive(RustcDecodable, Debug, PartialEq, Eq)]
+struct SpanTestData {
+    pub byte_start: u32,
+    pub byte_end: u32,
+    pub line_start: u32,
+    pub column_start: u32,
+    pub line_end: u32,
+    pub column_end: u32,
+}
+
+/// Test the span yields correct positions in JSON.
+fn test_positions(code: &str, span: (u32, u32), expected_output: SpanTestData) {
+    let expected_output = TestData { spans: vec![expected_output] };
+
+    with_default_globals(|| {
+        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
+        sm.new_source_file(Path::new("test.rs").to_owned().into(), code.to_owned());
+
+        let output = Arc::new(Mutex::new(Vec::new()));
+        let je = JsonEmitter::new(
+            Box::new(Shared { data: output.clone() }),
+            None,
+            sm,
+            true,
+            HumanReadableErrorType::Short(ColorConfig::Never),
+            false,
+        );
+
+        let span = Span::with_root_ctxt(BytePos(span.0), BytePos(span.1));
+        let handler = Handler::with_emitter(true, None, Box::new(je));
+        handler.span_err(span, "foo");
+
+        let bytes = output.lock().unwrap();
+        let actual_output = str::from_utf8(&bytes).unwrap();
+        let actual_output: TestData = decode(actual_output).unwrap();
+
+        assert_eq!(expected_output, actual_output)
+    })
+}
+
+#[test]
+fn empty() {
+    test_positions(
+        " ",
+        (0, 1),
+        SpanTestData {
+            byte_start: 0,
+            byte_end: 1,
+            line_start: 1,
+            column_start: 1,
+            line_end: 1,
+            column_end: 2,
+        },
+    )
+}
+
+#[test]
+fn bom() {
+    test_positions(
+        "\u{feff} ",
+        (0, 1),
+        SpanTestData {
+            byte_start: 3,
+            byte_end: 4,
+            line_start: 1,
+            column_start: 1,
+            line_end: 1,
+            column_end: 2,
+        },
+    )
+}
+
+#[test]
+fn lf_newlines() {
+    test_positions(
+        "\nmod foo;\nmod bar;\n",
+        (5, 12),
+        SpanTestData {
+            byte_start: 5,
+            byte_end: 12,
+            line_start: 2,
+            column_start: 5,
+            line_end: 3,
+            column_end: 3,
+        },
+    )
+}
+
+#[test]
+fn crlf_newlines() {
+    test_positions(
+        "\r\nmod foo;\r\nmod bar;\r\n",
+        (5, 12),
+        SpanTestData {
+            byte_start: 6,
+            byte_end: 14,
+            line_start: 2,
+            column_start: 5,
+            line_end: 3,
+            column_end: 3,
+        },
+    )
+}
+
+#[test]
+fn crlf_newlines_with_bom() {
+    test_positions(
+        "\u{feff}\r\nmod foo;\r\nmod bar;\r\n",
+        (5, 12),
+        SpanTestData {
+            byte_start: 9,
+            byte_end: 17,
+            line_start: 2,
+            column_start: 5,
+            line_end: 3,
+            column_end: 3,
+        },
+    )
+}
+
+#[test]
+fn span_before_crlf() {
+    test_positions(
+        "foo\r\nbar",
+        (2, 3),
+        SpanTestData {
+            byte_start: 2,
+            byte_end: 3,
+            line_start: 1,
+            column_start: 3,
+            line_end: 1,
+            column_end: 4,
+        },
+    )
+}
+
+#[test]
+fn span_on_crlf() {
+    test_positions(
+        "foo\r\nbar",
+        (3, 4),
+        SpanTestData {
+            byte_start: 3,
+            byte_end: 5,
+            line_start: 1,
+            column_start: 4,
+            line_end: 2,
+            column_end: 1,
+        },
+    )
+}
+
+#[test]
+fn span_after_crlf() {
+    test_positions(
+        "foo\r\nbar",
+        (4, 5),
+        SpanTestData {
+            byte_start: 5,
+            byte_end: 6,
+            line_start: 2,
+            column_start: 1,
+            line_end: 2,
+            column_end: 2,
+        },
+    )
+}
diff --git a/src/libsyntax/source_map.rs b/src/libsyntax/source_map.rs
index 7d0d2392945..359b5957167 100644
--- a/src/libsyntax/source_map.rs
+++ b/src/libsyntax/source_map.rs
@@ -283,6 +283,7 @@ impl SourceMap {
         mut file_local_lines: Vec<BytePos>,
         mut file_local_multibyte_chars: Vec<MultiByteChar>,
         mut file_local_non_narrow_chars: Vec<NonNarrowChar>,
+        mut file_local_normalized_pos: Vec<NormalizedPos>,
     ) -> Lrc<SourceFile> {
         let start_pos = self.next_start_pos();
 
@@ -301,6 +302,10 @@ impl SourceMap {
             *swc = *swc + start_pos;
         }
 
+        for nc in &mut file_local_normalized_pos {
+            nc.pos = nc.pos + start_pos;
+        }
+
         let source_file = Lrc::new(SourceFile {
             name: filename,
             name_was_remapped,
@@ -314,6 +319,7 @@ impl SourceMap {
             lines: file_local_lines,
             multibyte_chars: file_local_multibyte_chars,
             non_narrow_chars: file_local_non_narrow_chars,
+            normalized_pos: file_local_normalized_pos,
             name_hash,
         });
 
diff --git a/src/libsyntax/tests.rs b/src/libsyntax/tests.rs
index f510ac9273d..a95880d9620 100644
--- a/src/libsyntax/tests.rs
+++ b/src/libsyntax/tests.rs
@@ -110,8 +110,8 @@ struct SpanLabel {
     label: &'static str,
 }
 
-struct Shared<T: Write> {
-    data: Arc<Mutex<T>>,
+crate struct Shared<T: Write> {
+    pub data: Arc<Mutex<T>>,
 }
 
 impl<T: Write> Write for Shared<T> {