Tweak wording

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -2586,7 +2586,6 @@ impl<'a> Parser<'a> {
                 break;
             }
             if let Some(span) = self.diff_marker(&TokenKind::EqEq, &TokenKind::Eq) {
-                spans.push(span);
                 middle = Some(span);
             }
             if let Some(span) = self.diff_marker(&TokenKind::BinOp(token::Shr), &TokenKind::Gt) {
@@ -2597,13 +2596,25 @@ impl<'a> Parser<'a> {
             self.bump();
         }
         let mut err = self.struct_span_err(spans, "encountered diff marker");
-        err.span_label(start, "start");
+        err.span_label(start, "after this is the code before the merge");
         if let Some(middle) = middle {
-            err.span_label(middle, "middle");
+            err.span_label(middle, "");
         }
         if let Some(end) = end {
-            err.span_label(end, "end");
+            err.span_label(end, "above this are the incoming code changes");
         }
+        err.help(
+            "if you're having merge conflicts after pulling new code, the top section is the code \
+             you already had and the bottom section is the remote code",
+        );
+        err.help(
+            "if you're in the middle of a rebase, the top section is the code being rebased onto \
+             and the bottom section is the code coming from the current commit being rebased",
+        );
+        err.note(
+            "for an explanation on these markers from the `git` documentation, visit \
+             <https://git-scm.com/book/en/v2/Git-Tools-Advanced-Merging#_checking_out_conflicts>",
+        );
         err.emit();
         FatalError.raise()
     }

compiler/rustc_parse/src/parser/item.rs

@@ -1583,7 +1583,7 @@ impl<'a> Parser<'a> {
             p.collect_tokens_trailing_token(attrs, ForceCollect::No, |p, attrs| {
                 let mut snapshot = None;
                 if p.is_diff_marker(&TokenKind::BinOp(token::Shl), &TokenKind::Lt) {
-                    // Account for `<<<<<<<` diff markers. We can't proactivelly error here because
+                    // Account for `<<<<<<<` diff markers. We can't proactively error here because
                     // that can be a valid type start, so we snapshot and reparse only we've
                     // encountered another parse error.
                     snapshot = Some(p.create_snapshot_for_diagnostic());

compiler/rustc_parse/src/parser/stmt.rs

@@ -537,7 +537,7 @@ impl<'a> Parser<'a> {
                 break;
             }
             if self.is_diff_marker(&TokenKind::BinOp(token::Shl), &TokenKind::Lt) {
-                // Account for `<<<<<<<` diff markers. We can't proactivelly error here because
+                // Account for `<<<<<<<` diff markers. We can't proactively error here because
                 // that can be a valid path start, so we snapshot and reparse only we've
                 // encountered another parse error.
                 snapshot = Some(self.create_snapshot_for_diagnostic());

src/test/ui/parser/diff-markers/enum-2.stderr

@@ -2,13 +2,17 @@ error: encountered diff marker
   --> $DIR/enum-2.rs:3:1
    |
 LL | <<<<<<< HEAD
-   | ^^^^^^^ start
+   | ^^^^^^^ after this is the code before the merge
 LL |         x: u8,
 LL | =======
-   | ^^^^^^^ middle
+   | -------
 LL |         x: i8,
 LL | >>>>>>> branch
-   | ^^^^^^^ end
+   | ^^^^^^^ above this are the incoming code changes
+   |
+   = help: if you're having merge conflicts after pulling new code, the top section is the code you already had and the bottom section is the remote code
+   = help: if you're in the middle of a rebase, the top section is the code being rebased onto and the bottom section is the code coming from the current commit being rebased
+   = note: for an explanation on these markers from the `git` documentation, visit <https://git-scm.com/book/en/v2/Git-Tools-Advanced-Merging#_checking_out_conflicts>
 
 error: aborting due to previous error
 

src/test/ui/parser/diff-markers/enum.stderr

@@ -2,13 +2,17 @@ error: encountered diff marker
   --> $DIR/enum.rs:2:1
    |
 LL | <<<<<<< HEAD
-   | ^^^^^^^ start
+   | ^^^^^^^ after this is the code before the merge
 LL |     Foo(u8),
 LL | =======
-   | ^^^^^^^ middle
+   | -------
 LL |     Bar(i8),
 LL | >>>>>>> branch
-   | ^^^^^^^ end
+   | ^^^^^^^ above this are the incoming code changes
+   |
+   = help: if you're having merge conflicts after pulling new code, the top section is the code you already had and the bottom section is the remote code
+   = help: if you're in the middle of a rebase, the top section is the code being rebased onto and the bottom section is the code coming from the current commit being rebased
+   = note: for an explanation on these markers from the `git` documentation, visit <https://git-scm.com/book/en/v2/Git-Tools-Advanced-Merging#_checking_out_conflicts>
 
 error: aborting due to previous error
 

src/test/ui/parser/diff-markers/fn-arg.stderr

@@ -2,13 +2,17 @@ error: encountered diff marker
   --> $DIR/fn-arg.rs:3:1
    |
 LL | <<<<<<< HEAD
-   | ^^^^^^^ start
+   | ^^^^^^^ after this is the code before the merge
 LL |         x: u8,
 LL | =======
-   | ^^^^^^^ middle
+   | -------
 LL |         x: i8,
 LL | >>>>>>> branch
-   | ^^^^^^^ end
+   | ^^^^^^^ above this are the incoming code changes
+   |
+   = help: if you're having merge conflicts after pulling new code, the top section is the code you already had and the bottom section is the remote code
+   = help: if you're in the middle of a rebase, the top section is the code being rebased onto and the bottom section is the code coming from the current commit being rebased
+   = note: for an explanation on these markers from the `git` documentation, visit <https://git-scm.com/book/en/v2/Git-Tools-Advanced-Merging#_checking_out_conflicts>
 
 error: aborting due to previous error
 

src/test/ui/parser/diff-markers/item-with-attr.stderr

@@ -2,13 +2,17 @@ error: encountered diff marker
   --> $DIR/item-with-attr.rs:2:1
    |
 LL | <<<<<<< HEAD
-   | ^^^^^^^ start
+   | ^^^^^^^ after this is the code before the merge
 LL | fn foo() {}
 LL | =======
-   | ^^^^^^^ middle
+   | -------
 LL | fn bar() {}
 LL | >>>>>>> branch
-   | ^^^^^^^ end
+   | ^^^^^^^ above this are the incoming code changes
+   |
+   = help: if you're having merge conflicts after pulling new code, the top section is the code you already had and the bottom section is the remote code
+   = help: if you're in the middle of a rebase, the top section is the code being rebased onto and the bottom section is the code coming from the current commit being rebased
+   = note: for an explanation on these markers from the `git` documentation, visit <https://git-scm.com/book/en/v2/Git-Tools-Advanced-Merging#_checking_out_conflicts>
 
 error: aborting due to previous error
 

src/test/ui/parser/diff-markers/item.stderr

@@ -2,13 +2,17 @@ error: encountered diff marker
   --> $DIR/item.rs:1:1
    |
 LL | <<<<<<< HEAD
-   | ^^^^^^^ start
+   | ^^^^^^^ after this is the code before the merge
 LL | fn foo() {}
 LL | =======
-   | ^^^^^^^ middle
+   | -------
 LL | fn bar() {}
 LL | >>>>>>> branch
-   | ^^^^^^^ end
+   | ^^^^^^^ above this are the incoming code changes
+   |
+   = help: if you're having merge conflicts after pulling new code, the top section is the code you already had and the bottom section is the remote code
+   = help: if you're in the middle of a rebase, the top section is the code being rebased onto and the bottom section is the code coming from the current commit being rebased
+   = note: for an explanation on these markers from the `git` documentation, visit <https://git-scm.com/book/en/v2/Git-Tools-Advanced-Merging#_checking_out_conflicts>
 
 error: aborting due to previous error
 

src/test/ui/parser/diff-markers/statement.stderr

@@ -2,13 +2,17 @@ error: encountered diff marker
   --> $DIR/statement.rs:10:1
    |
 LL | <<<<<<< HEAD
-   | ^^^^^^^ start
+   | ^^^^^^^ after this is the code before the merge
 LL |     S::foo();
 LL | =======
-   | ^^^^^^^ middle
+   | -------
 LL |     S::bar();
 LL | >>>>>>> branch
-   | ^^^^^^^ end
+   | ^^^^^^^ above this are the incoming code changes
+   |
+   = help: if you're having merge conflicts after pulling new code, the top section is the code you already had and the bottom section is the remote code
+   = help: if you're in the middle of a rebase, the top section is the code being rebased onto and the bottom section is the code coming from the current commit being rebased
+   = note: for an explanation on these markers from the `git` documentation, visit <https://git-scm.com/book/en/v2/Git-Tools-Advanced-Merging#_checking_out_conflicts>
 
 error: aborting due to previous error
 

src/test/ui/parser/diff-markers/struct-expr.stderr

@@ -2,13 +2,17 @@ error: encountered diff marker
   --> $DIR/struct-expr.rs:6:1
    |
 LL | <<<<<<< HEAD
-   | ^^^^^^^ start
+   | ^^^^^^^ after this is the code before the merge
 LL |         x: 42,
 LL | =======
-   | ^^^^^^^ middle
+   | -------
 LL |         x: 0,
 LL | >>>>>>> branch
-   | ^^^^^^^ end
+   | ^^^^^^^ above this are the incoming code changes
+   |
+   = help: if you're having merge conflicts after pulling new code, the top section is the code you already had and the bottom section is the remote code
+   = help: if you're in the middle of a rebase, the top section is the code being rebased onto and the bottom section is the code coming from the current commit being rebased
+   = note: for an explanation on these markers from the `git` documentation, visit <https://git-scm.com/book/en/v2/Git-Tools-Advanced-Merging#_checking_out_conflicts>
 
 error: aborting due to previous error
 

src/test/ui/parser/diff-markers/struct.stderr

@@ -2,13 +2,17 @@ error: encountered diff marker
   --> $DIR/struct.rs:2:1
    |
 LL | <<<<<<< HEAD
-   | ^^^^^^^ start
+   | ^^^^^^^ after this is the code before the merge
 LL |     x: u8,
 LL | =======
-   | ^^^^^^^ middle
+   | -------
 LL |     x: i8,
 LL | >>>>>>> branch
-   | ^^^^^^^ end
+   | ^^^^^^^ above this are the incoming code changes
+   |
+   = help: if you're having merge conflicts after pulling new code, the top section is the code you already had and the bottom section is the remote code
+   = help: if you're in the middle of a rebase, the top section is the code being rebased onto and the bottom section is the code coming from the current commit being rebased
+   = note: for an explanation on these markers from the `git` documentation, visit <https://git-scm.com/book/en/v2/Git-Tools-Advanced-Merging#_checking_out_conflicts>
 
 error: aborting due to previous error
 

src/test/ui/parser/diff-markers/trait-item.stderr

@@ -2,13 +2,17 @@ error: encountered diff marker
   --> $DIR/trait-item.rs:2:1
    |
 LL | <<<<<<< HEAD
-   | ^^^^^^^ start
+   | ^^^^^^^ after this is the code before the merge
 LL |     fn foo() {}
 LL | =======
-   | ^^^^^^^ middle
+   | -------
 LL |     fn bar() {}
 LL | >>>>>>> branch
-   | ^^^^^^^ end
+   | ^^^^^^^ above this are the incoming code changes
+   |
+   = help: if you're having merge conflicts after pulling new code, the top section is the code you already had and the bottom section is the remote code
+   = help: if you're in the middle of a rebase, the top section is the code being rebased onto and the bottom section is the code coming from the current commit being rebased
+   = note: for an explanation on these markers from the `git` documentation, visit <https://git-scm.com/book/en/v2/Git-Tools-Advanced-Merging#_checking_out_conflicts>
 
 error: aborting due to previous error
 

src/test/ui/parser/diff-markers/tuple-struct.stderr

@@ -2,13 +2,17 @@ error: encountered diff marker
   --> $DIR/tuple-struct.rs:2:1
    |
 LL | <<<<<<< HEAD
-   | ^^^^^^^ start
+   | ^^^^^^^ after this is the code before the merge
 LL |     u8,
 LL | =======
-   | ^^^^^^^ middle
+   | -------
 LL |     i8,
 LL | >>>>>>> branch
-   | ^^^^^^^ end
+   | ^^^^^^^ above this are the incoming code changes
+   |
+   = help: if you're having merge conflicts after pulling new code, the top section is the code you already had and the bottom section is the remote code
+   = help: if you're in the middle of a rebase, the top section is the code being rebased onto and the bottom section is the code coming from the current commit being rebased
+   = note: for an explanation on these markers from the `git` documentation, visit <https://git-scm.com/book/en/v2/Git-Tools-Advanced-Merging#_checking_out_conflicts>
 
 error: aborting due to previous error
 

src/test/ui/parser/diff-markers/use-statement.stderr

@@ -2,13 +2,17 @@ error: encountered diff marker
   --> $DIR/use-statement.rs:2:1
    |
 LL | <<<<<<< HEAD
-   | ^^^^^^^ start
+   | ^^^^^^^ after this is the code before the merge
 LL |     bar,
 LL | =======
-   | ^^^^^^^ middle
+   | -------
 LL |     baz,
 LL | >>>>>>> branch
-   | ^^^^^^^ end
+   | ^^^^^^^ above this are the incoming code changes
+   |
+   = help: if you're having merge conflicts after pulling new code, the top section is the code you already had and the bottom section is the remote code
+   = help: if you're in the middle of a rebase, the top section is the code being rebased onto and the bottom section is the code coming from the current commit being rebased
+   = note: for an explanation on these markers from the `git` documentation, visit <https://git-scm.com/book/en/v2/Git-Tools-Advanced-Merging#_checking_out_conflicts>
 
 error: aborting due to previous error