slightly better error messages

unison-cli/src/Unison/Codebase/Editor/HandleInput/Merge2.hs

@@ -290,10 +290,10 @@ doMerge info = do
                 Cli.returnEarly case err of
                   IncoherentDeclReason'ConstructorAlias name1 name2 ->
                     Output.MergeConstructorAlias maybeBranchName name1 name2
-                  IncoherentDeclReason'MissingConstructorName name -> Output.MergeMissingConstructorName name
+                  IncoherentDeclReason'MissingConstructorName name -> Output.MergeMissingConstructorName maybeBranchName name
                   IncoherentDeclReason'NestedDeclAlias shorterName longerName ->
-                    Output.MergeNestedDeclAlias shorterName longerName
-                  IncoherentDeclReason'StrayConstructor name -> Output.MergeStrayConstructor name
+                    Output.MergeNestedDeclAlias maybeBranchName shorterName longerName
+                  IncoherentDeclReason'StrayConstructor name -> Output.MergeStrayConstructor maybeBranchName name
             pure (defns, declNameLookup)
 
     (aliceDefns0, aliceDeclNameLookup) <- load (Just (Just branchNames.alice.branch, branches.alice))

unison-cli/src/Unison/Codebase/Editor/Output.hs

@@ -404,9 +404,9 @@ data Output
   | MergeConflictInvolvingBuiltin !Name
   | MergeConstructorAlias !(Maybe ProjectBranchName) !Name !Name
   | MergeDefnsInLib !ProjectBranchName
-  | MergeMissingConstructorName !Name
-  | MergeNestedDeclAlias !Name !Name
-  | MergeStrayConstructor !Name
+  | MergeMissingConstructorName !(Maybe ProjectBranchName) !Name
+  | MergeNestedDeclAlias !(Maybe ProjectBranchName) !Name !Name
+  | MergeStrayConstructor !(Maybe ProjectBranchName) !Name
 
 data UpdateOrUpgrade = UOUUpdate | UOUUpgrade
 

unison-cli/src/Unison/CommandLine/OutputMessages.hs

@@ -1667,27 +1667,39 @@ notifyUser dir = \case
         <> "and"
         <> prettyName name2
         <> "are aliases. Every type declaration must have exactly one name for each constructor."
-  MergeDefnsInLib name ->
+  MergeDefnsInLib branch ->
     pure . P.wrap $
       "On"
-        <> P.group (prettyProjectBranchName name <> ",")
+        <> P.group (prettyProjectBranchName branch <> ",")
         <> "there's a type or term directly in the `lib` namespace, but I expected only library dependencies to be in there."
         <> "Please remove it before merging."
-  MergeMissingConstructorName name ->
+  MergeMissingConstructorName maybeBranch name ->
     pure . P.wrap $
-      "The type"
+      "On"
+        <> case maybeBranch of
+          Nothing -> "the LCA,"
+          Just branch -> P.group (prettyProjectBranchName branch <> ",")
+        <> "the type"
         <> prettyName name
         <> "is missing a name for one of its constructors. Please add one before merging."
-  MergeNestedDeclAlias shorterName longerName ->
+  MergeNestedDeclAlias maybeBranch shorterName longerName ->
     pure . P.wrap $
-      "The type"
+      "On"
+        <> case maybeBranch of
+          Nothing -> "the LCA,"
+          Just branch -> P.group (prettyProjectBranchName branch <> ",")
+        <> "the type"
         <> prettyName longerName
         <> "is an alias of"
         <> P.group (prettyName shorterName <> ".")
         <> "Type aliases cannot be nested. Please make them disjoint before merging."
-  MergeStrayConstructor name ->
+  MergeStrayConstructor maybeBranch name ->
     pure . P.wrap $
-      "The constructor"
+      "On"
+        <> case maybeBranch of
+          Nothing -> "the LCA,"
+          Just branch -> P.group (prettyProjectBranchName branch <> ",")
+        <> "the constructor"
         <> prettyName name
         <> "is not in a subnamespace of a name of its type."
         <> "Please either delete it or rename it before merging."

unison-src/transcripts/merge.output.md

@@ -1047,8 +1047,8 @@ bob = 100
 ```ucm
 project/alice> merge /bob
 
-  The type Foo is missing a name for one of its constructors.
-  Please add one before merging.
+  On alice, the type Foo is missing a name for one of its
+  constructors. Please add one before merging.
 
 ```
 ### Nested decl alias
@@ -1080,8 +1080,8 @@ bob = 100
 ```ucm
 project/alice> merge /bob
 
-  The type A.inner.X is an alias of A. Type aliases cannot be
-  nested. Please make them disjoint before merging.
+  On alice, the type A.inner.X is an alias of A. Type aliases
+  cannot be nested. Please make them disjoint before merging.
 
 ```
 ### Stray constructor alias
@@ -1113,7 +1113,7 @@ project/bob> add
 ```ucm
 project/alice> merge bob
 
-  The constructor AliasOutsideFooNamespace is not in a
+  On alice, the constructor AliasOutsideFooNamespace is not in a
   subnamespace of a name of its type. Please either delete it or
   rename it before merging.