diff rust/hg-core/src/copy_tracing.rs @ 46606:c692384bb559

copies: rearrange all value comparison conditional

To properly handle the newly tested case (chaining of merges) we will need to
detect more accurately when an actualy merging of the copy information (and
superseed the two existing data). Before starting to do so, we need to
reorganise the values comparison to introduce different conditional branches
when such actual merging is needed/detected.

To avoid mixing too many change in this complicated code, we do the
reorganisation before adding the "overwrite detection" logic in the next
changesets.

Differential Revision: https://phab.mercurial-scm.org/D9612

--- a/rust/hg-core/src/copy_tracing.rs	Mon Feb 22 12:21:00 2021 +0100
+++ b/rust/hg-core/src/copy_tracing.rs	Mon Dec 14 19:26:33 2020 +0100
@@ -746,6 +746,8 @@
             MergePick::Any
         } else if oracle.is_overwrite(src_major.rev, src_minor.rev) {
             MergePick::Minor
+        } else if oracle.is_overwrite(src_minor.rev, src_major.rev) {
+            MergePick::Major
         } else {
             MergePick::Major
         }
@@ -753,45 +755,61 @@
         // We cannot get copy information for both p1 and p2 in the
         // same rev. So this is the same value.
         unreachable!(
-            "conflict information from p1 and p2 in the same revision"
+            "conflicting information from p1 and p2 in the same revision"
         );
     } else {
         let dest_path = path_map.untokenize(*dest);
         let action = changes.get_merge_case(dest_path);
-        if src_major.path.is_none() && action == MergeCase::Salvaged {
+        if src_minor.path.is_some()
+            && src_major.path.is_none()
+            && action == MergeCase::Salvaged
+        {
             // If the file is "deleted" in the major side but was
             // salvaged by the merge, we keep the minor side alive
             MergePick::Minor
-        } else if src_minor.path.is_none() && action == MergeCase::Salvaged {
+        } else if src_major.path.is_some()
+            && src_minor.path.is_none()
+            && action == MergeCase::Salvaged
+        {
             // If the file is "deleted" in the minor side but was
             // salvaged by the merge, unconditionnaly preserve the
             // major side.
             MergePick::Major
-        } else if action == MergeCase::Merged {
-            // If the file was actively merged, copy information
-            // from each side might conflict.  The major side will
-            // win such conflict.
-            MergePick::Major
+        } else if oracle.is_overwrite(src_minor.rev, src_major.rev) {
+            // The information from the minor version are strictly older than
+            // the major version
+            if action == MergeCase::Merged {
+                // If the file was actively merged, its means some non-copy
+                // activity happened on the other branch. It
+                // mean the older copy information are still relevant.
+                //
+                // The major side wins such conflict.
+                MergePick::Major
+            } else {
+                // No activity on the minor branch, pick the newer one.
+                MergePick::Major
+            }
         } else if oracle.is_overwrite(src_major.rev, src_minor.rev) {
-            // If the minor side is strictly newer than the major
-            // side, it should be kept.
-            MergePick::Minor
-        } else if src_major.path.is_some() {
-            // without any special case, the "major" value win
-            // other the "minor" one.
+            if action == MergeCase::Merged {
+                // If the file was actively merged, its means some non-copy
+                // activity happened on the other branch. It
+                // mean the older copy information are still relevant.
+                //
+                // The major side wins such conflict.
+                MergePick::Major
+            } else {
+                // No activity on the minor branch, pick the newer one.
+                MergePick::Minor
+            }
+        } else if src_minor.path.is_none() {
+            // the minor side has no relevant information, pick the alive one
             MergePick::Major
-        } else if oracle.is_overwrite(src_minor.rev, src_major.rev) {
-            // the "major" rev is a direct ancestors of "minor",
-            // any different value should
-            // overwrite
-            MergePick::Major
+        } else if src_major.path.is_none() {
+            // the major side has no relevant information, pick the alive one
+            MergePick::Minor
         } else {
-            // major version is None (so the file was deleted on
-            // that branch) and that branch is independant (neither
-            // minor nor major is an ancestors of the other one.)
-            // We preserve the new
-            // information about the new file.
-            MergePick::Minor
+            // by default the major side wins
+            MergePick::Major
         }
     }
 }