Properly colorize multi-part suggestions in the same line

Fix #108547.

compiler/rustc_errors/src/emitter.rs

@@ -1895,7 +1895,7 @@ impl EmitterWriter {
                         self.draw_code_line(
                             &mut buffer,
                             &mut row_num,
-                            &Vec::new(),
+                            &[],
                             p + line_start,
                             l,
                             show_code_change,
@@ -1919,7 +1919,7 @@ impl EmitterWriter {
                             self.draw_code_line(
                                 &mut buffer,
                                 &mut row_num,
-                                &Vec::new(),
+                                &[],
                                 p + line_start,
                                 l,
                                 show_code_change,
@@ -1936,7 +1936,7 @@ impl EmitterWriter {
                             self.draw_code_line(
                                 &mut buffer,
                                 &mut row_num,
-                                &Vec::new(),
+                                &[],
                                 p + line_start,
                                 l,
                                 show_code_change,
@@ -1951,7 +1951,7 @@ impl EmitterWriter {
                 self.draw_code_line(
                     &mut buffer,
                     &mut row_num,
-                    highlight_parts,
+                    &highlight_parts,
                     line_pos + line_start,
                     line,
                     show_code_change,
@@ -2176,7 +2176,7 @@ impl EmitterWriter {
         &self,
         buffer: &mut StyledBuffer,
         row_num: &mut usize,
-        highlight_parts: &Vec<SubstitutionHighlight>,
+        highlight_parts: &[SubstitutionHighlight],
         line_num: usize,
         line_to_add: &str,
         show_code_change: DisplaySuggestion,

compiler/rustc_errors/src/lib.rs

@@ -331,7 +331,7 @@ impl CodeSuggestion {
                     });
                     buf.push_str(&part.snippet);
                     let cur_hi = sm.lookup_char_pos(part.span.hi());
-                    if prev_hi.line == cur_lo.line && cur_hi.line == cur_lo.line {
+                    if cur_hi.line == cur_lo.line {
                         // Account for the difference between the width of the current code and the
                         // snippet being suggested, so that the *later* suggestions are correctly
                         // aligned on the screen.

tests/ui/suggestions/multiline-multipart-suggestion.rs

@@ -0,0 +1,19 @@
+// compile-flags: --error-format=human --color=always
+// ignore-windows
+
+fn short(foo_bar: &Vec<&i32>) -> &i32 { //~ ERROR missing lifetime specifier
+    &12
+}
+
+fn long( //~ ERROR missing lifetime specifier
+    foo_bar: &Vec<&i32>,
+    something_very_long_so_that_the_line_will_wrap_around__________: i32,
+) -> &i32 {
+    &12
+}
+
+fn long2( //~ ERROR missing lifetime specifier
+    foo_bar: &Vec<&i32>) -> &i32 {
+    &12
+}
+fn main() {}

tests/ui/suggestions/multiline-multipart-suggestion.stderr

@@ -0,0 +1,46 @@
+error[E0106]: missing lifetime specifier
+  --> $DIR/multiline-multipart-suggestion.rs:4:34
+   |
+LL | fn short(foo_bar: &Vec<&i32>) -> &i32 {
+   |                   ----------     ^ expected named lifetime parameter
+   |
+   = help: this function's return type contains a borrowed value, but the signature does not say which one of `foo_bar`'s 2 lifetimes it is borrowed from
+help: consider introducing a named lifetime parameter
+   |
+LL | fn short<'a>(foo_bar: &'a Vec<&'a i32>) -> &'a i32 {
+   |         ++++           ++      ++           ++
+
+error[E0106]: missing lifetime specifier
+  --> $DIR/multiline-multipart-suggestion.rs:11:6
+   |
+LL |     foo_bar: &Vec<&i32>,
+   |              ----------
+LL |     something_very_long_so_that_the_line_will_wrap_around__________: i32,
+LL | ) -> &i32 {
+   |      ^ expected named lifetime parameter
+   |
+   = help: this function's return type contains a borrowed value, but the signature does not say which one of `foo_bar`'s 2 lifetimes it is borrowed from
+help: consider introducing a named lifetime parameter
+   |
+LL ~ fn long<'a>(
+LL ~     foo_bar: &'a Vec<&'a i32>,
+LL |     something_very_long_so_that_the_line_will_wrap_around__________: i32,
+LL ~ ) -> &'a i32 {
+   |
+
+error[E0106]: missing lifetime specifier
+  --> $DIR/multiline-multipart-suggestion.rs:16:29
+   |
+LL |     foo_bar: &Vec<&i32>) -> &i32 {
+   |              ----------     ^ expected named lifetime parameter
+   |
+   = help: this function's return type contains a borrowed value, but the signature does not say which one of `foo_bar`'s 2 lifetimes it is borrowed from
+help: consider introducing a named lifetime parameter
+   |
+LL ~ fn long2<'a>(
+LL ~     foo_bar: &'a Vec<&'a i32>) -> &'a i32 {
+   |
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0106`.