Be more accurate about calculating display_col from a BytePos

No longer track "zero-width" chars in `SourceMap`, read directly from the line when calculating the `display_col` of a `BytePos`. Move `char_width` to `rustc_span` and use it from the emitter.

This change allows the following to properly align in terminals (depending on the font, the replaced control codepoints are rendered as 1 or 2 width, on my terminal they are rendered as 1, on VSCode text they are rendered as 2):

```
error: this file contains an unclosed delimiter
  --> $DIR/issue-68629.rs:5:17
   |
LL | ␜␟ts␀![{i
   |       -- unclosed delimiter
   |       |
   |       unclosed delimiter
LL | ␀␀  fn rݻoa>rݻm
   |                ^
```

Author: estebank

Diff for: compiler/rustc_errors/Cargo.toml

@@ -26,7 +26,6 @@ serde_json = "1.0.59"
 termcolor = "1.2.0"
 termize = "0.1.1"
 tracing = "0.1"
-unicode-width = "0.1.4"
 # tidy-alphabetical-end
 
 [target.'cfg(windows)'.dependencies.windows]

Diff for: compiler/rustc_errors/src/emitter.rs

@@ -8,7 +8,7 @@
 //! The output types are defined in `rustc_session::config::ErrorOutputType`.
 
 use rustc_span::source_map::SourceMap;
-use rustc_span::{FileLines, FileName, SourceFile, Span};
+use rustc_span::{char_width, FileLines, FileName, SourceFile, Span};
 
 use crate::snippet::{
     Annotation, AnnotationColumn, AnnotationType, Line, MultilineAnnotation, Style, StyledString,
@@ -2614,21 +2614,6 @@ fn normalize_whitespace(str: &str) -> String {
     s
 }
 
-fn char_width(ch: char) -> usize {
-    // FIXME: `unicode_width` sometimes disagrees with terminals on how wide a `char` is. For now,
-    // just accept that sometimes the code line will be longer than desired.
-    match ch {
-        '\t' => 4,
-        '\u{0000}' | '\u{0001}' | '\u{0002}' | '\u{0003}' | '\u{0004}' | '\u{0005}'
-        | '\u{0006}' | '\u{0007}' | '\u{0008}' | '\u{000B}' | '\u{000C}' | '\u{000D}'
-        | '\u{000E}' | '\u{000F}' | '\u{0010}' | '\u{0011}' | '\u{0012}' | '\u{0013}'
-        | '\u{0014}' | '\u{0015}' | '\u{0016}' | '\u{0017}' | '\u{0018}' | '\u{0019}'
-        | '\u{001A}' | '\u{001B}' | '\u{001C}' | '\u{001D}' | '\u{001E}' | '\u{001F}'
-        | '\u{007F}' => 1,
-        _ => unicode_width::UnicodeWidthChar::width(ch).unwrap_or(1),
-    }
-}
-
 fn draw_col_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
     buffer.puts(line, col, "| ", Style::LineNumber);
 }

Diff for: compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -1727,7 +1727,6 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                     source_len,
                     lines,
                     multibyte_chars,
-                    non_narrow_chars,
                     normalized_pos,
                     stable_id,
                     ..
@@ -1779,7 +1778,6 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                     self.cnum,
                     lines,
                     multibyte_chars,
-                    non_narrow_chars,
                     normalized_pos,
                     source_file_index,
                 );

Diff for: compiler/rustc_query_system/src/ich/impls_syntax.rs

@@ -73,7 +73,6 @@ impl<'a> HashStable<StableHashingContext<'a>> for SourceFile {
             source_len: _,
             lines: _,
             ref multibyte_chars,
-            ref non_narrow_chars,
             ref normalized_pos,
         } = *self;
 
@@ -98,11 +97,6 @@ impl<'a> HashStable<StableHashingContext<'a>> for SourceFile {
             char_pos.hash_stable(hcx, hasher);
         }
 
-        non_narrow_chars.len().hash_stable(hcx, hasher);
-        for &char_pos in non_narrow_chars.iter() {
-            char_pos.hash_stable(hcx, hasher);
-        }
-
         normalized_pos.len().hash_stable(hcx, hasher);
         for &char_pos in normalized_pos.iter() {
             char_pos.hash_stable(hcx, hasher);

Diff for: compiler/rustc_span/src/analyze_source_file.rs

@@ -1,5 +1,4 @@
 use super::*;
-use unicode_width::UnicodeWidthChar;
 
 #[cfg(test)]
 mod tests;
@@ -9,15 +8,12 @@ mod tests;
 ///
 /// This function will use an SSE2 enhanced implementation if hardware support
 /// is detected at runtime.
-pub fn analyze_source_file(
-    src: &str,
-) -> (Vec<RelativeBytePos>, Vec<MultiByteChar>, Vec<NonNarrowChar>) {
+pub fn analyze_source_file(src: &str) -> (Vec<RelativeBytePos>, Vec<MultiByteChar>) {
     let mut lines = vec![RelativeBytePos::from_u32(0)];
     let mut multi_byte_chars = vec![];
-    let mut non_narrow_chars = vec![];
 
     // Calls the right implementation, depending on hardware support available.
-    analyze_source_file_dispatch(src, &mut lines, &mut multi_byte_chars, &mut non_narrow_chars);
+    analyze_source_file_dispatch(src, &mut lines, &mut multi_byte_chars);
 
     // The code above optimistically registers a new line *after* each \n
     // it encounters. If that point is already outside the source_file, remove
@@ -30,29 +26,26 @@ pub fn analyze_source_file(
         }
     }
 
-    (lines, multi_byte_chars, non_narrow_chars)
+    (lines, multi_byte_chars)
 }
 
 cfg_match! {
     cfg(any(target_arch = "x86", target_arch = "x86_64")) => {
         fn analyze_source_file_dispatch(src: &str,
                                     lines: &mut Vec<RelativeBytePos>,
-                                    multi_byte_chars: &mut Vec<MultiByteChar>,
-                                    non_narrow_chars: &mut Vec<NonNarrowChar>) {
+                                    multi_byte_chars: &mut Vec<MultiByteChar>) {
             if is_x86_feature_detected!("sse2") {
                 unsafe {
                     analyze_source_file_sse2(src,
                                          lines,
-                                         multi_byte_chars,
-                                         non_narrow_chars);
+                                         multi_byte_chars);
                 }
             } else {
                 analyze_source_file_generic(src,
                                         src.len(),
                                         RelativeBytePos::from_u32(0),
                                         lines,
-                                        multi_byte_chars,
-                                        non_narrow_chars);
+                                        multi_byte_chars);
 
             }
         }
@@ -64,8 +57,7 @@ cfg_match! {
         #[target_feature(enable = "sse2")]
         unsafe fn analyze_source_file_sse2(src: &str,
                                        lines: &mut Vec<RelativeBytePos>,
-                                       multi_byte_chars: &mut Vec<MultiByteChar>,
-                                       non_narrow_chars: &mut Vec<NonNarrowChar>) {
+                                       multi_byte_chars: &mut Vec<MultiByteChar>) {
             #[cfg(target_arch = "x86")]
             use std::arch::x86::*;
             #[cfg(target_arch = "x86_64")]
@@ -157,7 +149,6 @@ cfg_match! {
                     RelativeBytePos::from_usize(scan_start),
                     lines,
                     multi_byte_chars,
-                    non_narrow_chars
                 );
             }
 
@@ -168,23 +159,20 @@ cfg_match! {
                                         src.len() - tail_start,
                                         RelativeBytePos::from_usize(tail_start),
                                         lines,
-                                        multi_byte_chars,
-                                        non_narrow_chars);
+                                        multi_byte_chars);
             }
         }
     }
     _ => {
         // The target (or compiler version) does not support SSE2 ...
         fn analyze_source_file_dispatch(src: &str,
                                     lines: &mut Vec<RelativeBytePos>,
-                                    multi_byte_chars: &mut Vec<MultiByteChar>,
-                                    non_narrow_chars: &mut Vec<NonNarrowChar>) {
+                                    multi_byte_chars: &mut Vec<MultiByteChar>) {
             analyze_source_file_generic(src,
                                     src.len(),
                                     RelativeBytePos::from_u32(0),
                                     lines,
-                                    multi_byte_chars,
-                                    non_narrow_chars);
+                                    multi_byte_chars);
         }
     }
 }
@@ -198,7 +186,6 @@ fn analyze_source_file_generic(
     output_offset: RelativeBytePos,
     lines: &mut Vec<RelativeBytePos>,
     multi_byte_chars: &mut Vec<MultiByteChar>,
-    non_narrow_chars: &mut Vec<NonNarrowChar>,
 ) -> usize {
     assert!(src.len() >= scan_len);
     let mut i = 0;
@@ -220,16 +207,8 @@ fn analyze_source_file_generic(
 
             let pos = RelativeBytePos::from_usize(i) + output_offset;
 
-            match byte {
-                b'\n' => {
-                    lines.push(pos + RelativeBytePos(1));
-                }
-                b'\t' => {
-                    non_narrow_chars.push(NonNarrowChar::Tab(pos));
-                }
-                _ => {
-                    non_narrow_chars.push(NonNarrowChar::ZeroWidth(pos));
-                }
+            if let b'\n' = byte {
+                lines.push(pos + RelativeBytePos(1));
             }
         } else if byte >= 127 {
             // The slow path:
@@ -245,14 +224,6 @@ fn analyze_source_file_generic(
                 let mbc = MultiByteChar { pos, bytes: char_len as u8 };
                 multi_byte_chars.push(mbc);
             }
-
-            // Assume control characters are zero width.
-            // FIXME: How can we decide between `width` and `width_cjk`?
-            let char_width = UnicodeWidthChar::width(c).unwrap_or(0);
-
-            if char_width != 1 {
-                non_narrow_chars.push(NonNarrowChar::new(pos, char_width));
-            }
         }
 
         i += char_len;

Diff for: compiler/rustc_span/src/analyze_source_file/tests.rs

@@ -4,11 +4,10 @@ macro_rules! test {
     (case: $test_name:ident,
      text: $text:expr,
      lines: $lines:expr,
-     multi_byte_chars: $multi_byte_chars:expr,
-     non_narrow_chars: $non_narrow_chars:expr,) => {
+     multi_byte_chars: $multi_byte_chars:expr,) => {
         #[test]
         fn $test_name() {
-            let (lines, multi_byte_chars, non_narrow_chars) = analyze_source_file($text);
+            let (lines, multi_byte_chars) = analyze_source_file($text);
 
             let expected_lines: Vec<RelativeBytePos> =
                 $lines.into_iter().map(RelativeBytePos).collect();
@@ -21,13 +20,6 @@ macro_rules! test {
                 .collect();
 
             assert_eq!(multi_byte_chars, expected_mbcs);
-
-            let expected_nncs: Vec<NonNarrowChar> = $non_narrow_chars
-                .into_iter()
-                .map(|(pos, width)| NonNarrowChar::new(RelativeBytePos(pos), width))
-                .collect();
-
-            assert_eq!(non_narrow_chars, expected_nncs);
         }
     };
 }
@@ -37,93 +29,81 @@ test!(
     text: "",
     lines: vec![],
     multi_byte_chars: vec![],
-    non_narrow_chars: vec![],
 );
 
 test!(
     case: newlines_short,
     text: "a\nc",
     lines: vec![0, 2],
     multi_byte_chars: vec![],
-    non_narrow_chars: vec![],
 );
 
 test!(
     case: newlines_long,
     text: "012345678\nabcdef012345678\na",
     lines: vec![0, 10, 26],
     multi_byte_chars: vec![],
-    non_narrow_chars: vec![],
 );
 
 test!(
     case: newline_and_multi_byte_char_in_same_chunk,
     text: "01234β789\nbcdef0123456789abcdef",
     lines: vec![0, 11],
     multi_byte_chars: vec![(5, 2)],
-    non_narrow_chars: vec![],
 );
 
 test!(
     case: newline_and_control_char_in_same_chunk,
     text: "01234\u{07}6789\nbcdef0123456789abcdef",
     lines: vec![0, 11],
     multi_byte_chars: vec![],
-    non_narrow_chars: vec![(5, 0)],
 );
 
 test!(
     case: multi_byte_char_short,
     text: "aβc",
     lines: vec![0],
     multi_byte_chars: vec![(1, 2)],
-    non_narrow_chars: vec![],
 );
 
 test!(
     case: multi_byte_char_long,
     text: "0123456789abcΔf012345β",
     lines: vec![0],
     multi_byte_chars: vec![(13, 2), (22, 2)],
-    non_narrow_chars: vec![],
 );
 
 test!(
     case: multi_byte_char_across_chunk_boundary,
     text: "0123456789abcdeΔ123456789abcdef01234",
     lines: vec![0],
     multi_byte_chars: vec![(15, 2)],
-    non_narrow_chars: vec![],
 );
 
 test!(
     case: multi_byte_char_across_chunk_boundary_tail,
     text: "0123456789abcdeΔ....",
     lines: vec![0],
     multi_byte_chars: vec![(15, 2)],
-    non_narrow_chars: vec![],
 );
 
 test!(
     case: non_narrow_short,
     text: "0\t2",
     lines: vec![0],
     multi_byte_chars: vec![],
-    non_narrow_chars: vec![(1, 4)],
 );
 
 test!(
     case: non_narrow_long,
     text: "01\t3456789abcdef01234567\u{07}9",
     lines: vec![0],
     multi_byte_chars: vec![],
-    non_narrow_chars: vec![(2, 4), (24, 0)],
 );
 
 test!(
     case: output_offset_all,
     text: "01\t345\n789abcΔf01234567\u{07}9\nbcΔf",
     lines: vec![0, 7, 27],
     multi_byte_chars: vec![(13, 2), (29, 2)],
-    non_narrow_chars: vec![(2, 4), (24, 0)],
 );